Bostick and Sullivan Ziatype kit

Five bottles, two bags of powder, five droppers and a twelve-page sheet that names every chemical in the box. After the cyanotype kit from the same company, whose four pages of instructions do not contain the words ferric ammonium citrate, that is a startling improvement and it deserves saying first: this is the best-documented kit Bostick & Sullivan publishes. It gives a history with names and dates. It gives a density range for the negative. It gives a humidity range for the room and two ways of reaching it. It gives a colour chart of eleven starting points, credited to Richard Sullivan and Carl Weese. It gives a development time, a clearing time, a wash time and a capacity for the clearing bath.

And then it stops one number short, twice, in the same place.

The strength of the lithium palladium solution is not published. The strength of the ferric ammonium oxalate solution is not published. Those are the two bottles that make the photograph, and the entire published colour and contrast system of this kit is a table of drop counts — twelve of this against twelve of that, ten and two, four and eight. A drop count is a ratio, and a ratio needs both terms. A reader can work out from the maker’s own figures that the gold bottle is somewhere near 0.13 molar; nothing published anywhere says what it is 0.13 molar against. The same company, on the shelf beside it, sells the classic developing-out palladium as “Sodium Chloropalladite 15% solution” and adds that one 25 ml bottle is 625 drops. For the lithium bottle in this box it publishes the words “Lithium Chloropalladite solution” and a full stop.

That is the whole of this page’s argument, and everything else follows from it: a kit that documents its procedure better than any of its rivals and its chemistry not at all, sold for a process whose selling point is that the chemistry is the control.

The open formula it should be read against is Ware’s print-out platino-palladiotype — the same process, from the same ancestor, with the ammonium cation kept and every strength printed. The kit’s own instruction sheet names Ware and credits him; Ware, in his own monograph, says the substitution this kit is built on rests on an erroneous supposition. Both statements are recorded below, neither is suppressed, and the course says which it follows and why.

Bostick & Sullivan, Inc. — sold as kit

Components the maker discloses — from the safety data sheet, which classifies hazards and does not state a formula

Component	Concentration as the sheet gives it	Hazard codes
Lithium Palladium Solution25 ml, and the image metal. Identified on a store listing as "Lithium Chloropalladite solution. Standard for Ziatype." and nowhere else; the instruction sheet calls it "Lithium Palladium", describes it as dark brown, says it "will last almost indefinitely", "does not oxidize or age", must never be contaminated with the ferric ammonium oxalate, and must be kept in glass "never metal as the palladium will plate out on the container". No strength, no formula, no molarity and no CAS number are published anywhere. The concentration column is empty because the maker states nothing, not because this page has omitted it	—
Ammonium iron(III) oxalatenamed on the sheet as Ferric Ammonium Oxalate SolutionCAS 13268-42-325 ml, and "the chemical in your emulsion mix that is sensitive to light" — the maker's own words, and the only chemical statement the sheet makes about any bottle. Green, with a stated life of two to three years. The strength is not published for the solution; the CAS number here is the one the company prints for the solid it sells by the jar and files a sheet for, and that solid is a different object from the liquid in the kit	—
Sodium TungstateCAS 10213-10-225 ml. The warm-tone additive and the only contrast-reducing agent in the box — "It adds a warm tone to the print and also reduces contrast" — added at two or three drops against twelve of each of the other two in the maker's own chart. Its mechanism is not stated by the maker and this course could not find it stated by anybody	40%
Chloroauric acidnamed on the sheet as Gold Chloride10 ml, and the split-tone and contrast additive, used by replacing part of the palladium rather than by adding to it. The maker says it "will increase contrast (increasing contrast always increases exposure time) and give you split tones", and that "Depending on the ratios used with palladium and sodium tungstate, you can get pink, purple, blue, and sometimes green split tones". The compound is named on the store listing and never in the box	5%
Ammonium dichromateCAS 7789-09-525 ml, and the maker's contrast agent, offered at one or two drops per print. This course gives no procedure for it: ammonium dichromate is a chromium(VI) compound and the chromium ruling is that chromium(VI) is never used, at any level, anywhere. The bottle is recorded here because it is in the box and a reader will find it, and because the maker's own note about it is the strongest safety statement anywhere in this kit's literature	1%	H272, H301, H312, H314, H317, H330, H334, H340, H350, H360, H372
EDTA Clearing AgentCAS 13235-36-4250 g of powder, used with the bisulfite at two tablespoons of each in a quart, a litre or 1.5 litres of water according to which of the sheet's three printings you follow. It is the chelating half of the clearing bath, holding the unreduced iron in solution so that it leaves the paper instead of hydrolysing in it. The sheet in the box names no salt; the identification comes from the store listing and from the single EDTA sheet in the company's library, both of which say tetrasodium	95-100 %	H302, H315, H319, H331
Sodium metabisulfitenamed on the sheet as Sodium BisulfiteCAS 7681-57-4250 g of powder, the reducing half of the same single clearing bath. The kit labels it sodium bisulfite; the CAS number the maker prints beside that name, and the sheet it files for it, are both sodium metabisulfite's	≥ 97 %

Not disclosed. Bostick & Sullivan names every chemical in this box and publishes a strength for three of them — 40 per cent sodium tungstate, 5 per cent gold chloride, 1 per cent ammonium dichromate — and publishes no strength at all for the two that make the photograph. The lithium palladium solution is identified on a store listing as "Lithium Chloropalladite solution" and nowhere given a concentration, a formula, a molarity or a CAS number; the ferric ammonium oxalate solution is not even identified that far, and the only strength anywhere near it belongs to the solid the company sells by the jar. That silence is load-bearing rather than incidental, because the entire published colour and contrast system of this kit is a table of drop counts, and a drop count is a ratio whose denominator has not been published: a reader can work out that the gold bottle is about 0.13 molar and cannot work out what it is 0.13 molar against. The maker publishes no pH for any of the five solutions, no assay or hydrate for any solid, no exposure time for any named ultraviolet source, no yield for the kit in prints, no drop volume for the five supplied droppers, and no sensitometry of any kind — no exposure scale, no maximum density, no speed, no curve — although the sheet does specify the negative it wants at a density range of 1.35 to 1.50. It does not say what is in the bottles besides the named salt: no humectant, no surfactant, no acid, no preservative is either named or ruled out, and the sheet's own recommendation to add Tween 20 implies that no wetting agent is present without ever saying so. It does not say whether the 250 g clearing powder is the tetrasodium EDTA that its own store listing and its own library sheet name, because the sheet in the box calls it only "EDTA clearing agent". And the documentary boundary is the same as on every page in this lane: the company's safety data sheet library runs to eighty-nine sheets, every one for a single substance sold loose, and there is no sheet for this kit, none for the lithium chloropalladite the company manufactures in house, and none for the gold chloride it also manufactures in house. A reader who wants to know what has been classified about the two bottles that matter will find that the answer is nothing whatever.

Nearest open formula. Ware's print-out platino-palladiotype — The same process, from the same ancestor, with one deliberate substitution and one large documentary difference. Both are print-out palladium built on ammonium iron(III) oxalate; both coat, humidify, expose to completion under a negative, develop in plain water and clear with EDTA and a sulfite; both take their descent from Pizzighelli, and the kit's own instruction sheet says so and credits Ware by name. The substitution is the cation: Ware uses ammonium tetrachloropalladate(II) at a published 19 per cent w/v because the ammonium ion is a structure-breaking cation that lets a little absorbed water mobilise a great many ions, and Bostick & Sullivan uses lithium chloropalladite at a strength it does not publish. Ware's stated view, in print, is that the lithium substitution rests on an erroneous supposition, that lithium is one of the worst cations for this purpose, and that it is why a Ziatype can only ever be palladium and never platinum; the maker's stated view, also in print, is that the substitution is what makes colour and contrast chemical rather than humidity-locked, and the Getty atlas describes the process in those terms too. The documentary difference is the one a buyer feels: every number in the open formula is published, so the sensitiser can be reproduced next year and its molar ratios can be checked, while the kit's whole published colour system is a table of drop counts with no strength attached to the two bottles being counted. What the kit adds is five bottles already made up, five droppers, an eleven-row colour chart nobody has published an equivalent of, and a route to purple and blue split tones that the open formula does not offer at all. What the open formula adds is a stated strength for everything, a reason for every choice, a humidity method that is measured rather than judged by the sound of the paper, and a three-bath clearing sequence whose order is argued from the pH at which each chelate forms.

Purpose

To make a palladium print that develops itself in the printing frame, and to let its colour be chosen in the shot glass rather than found by luck.

Two things are being sold here and they are worth separating. The first is the print-out route: coat, humidify, expose under a negative until it looks right, wash in plain water. There is no developer, so there is no bath to exhaust, no temperature to hold and no test strip to guess from — the image is finished, in metal, before the frame is opened. That is Pizzighelli’s idea from the late 1880s, reworked in the 1980s by Mike Ware and Pradip Malde, and the maker’s own history page says so in as many words.

The second is the colour system, and it is the part that is genuinely this company’s. A palladium print-out sheet held at a given humidity gives the colour that humidity dictates; the printer’s control is the weather. The Ziatype’s proposition is that colour and contrast should instead be things you count into a glass: so many drops of palladium, so many of gold, so many of tungstate, and a dichromate bottle for when more contrast is wanted. The Getty Conservation Institute’s atlas puts it the same way — tonality and contrast here “are controlled chemically, unlike other Pizzighelli processes in which both tonality and contrast are controlled by humidity” — and that is a fair summary of what the box is for.

	The Ziatype kit
Image metal	Lithium chloropalladite, 25 ml, strength not published
Light-sensitive salt	Ferric ammonium oxalate solution, 25 ml, strength not published
Warm tone, less contrast	Sodium tungstate, 25 ml at 40 %
Split tones, more contrast	Gold chloride, 10 ml at 5 %
More contrast, cooler	Ammonium dichromate, 25 ml at 1 % — not used by this course
Clearing	250 g EDTA clearing agent and 250 g sodium bisulfite
Also in the box	five droppers, twelve pages of instructions
Developer	none: plain water
Stated yield	none published
Safety data sheet for any solution in the box	none published

A third thing is being sold implicitly and should be named, because it is why the humidity sections run to three pages: this process needs the paper wet at the moment of exposure, and wet paper in contact with a negative is a problem. The sheet’s answer is a sandwich of acetate on both sides of the sheet, and it is honest about what that costs: “fall out spots or blurry spots in your print are much more common. The paper is basically drying and moving while exposing.”

Recommended uses

A palladium print without a developer, a thermometer or a second bath. The shortest route in this formulary from a flat box to a noble-metal print. Coat, dry to the right dampness, expose by inspection, two minutes in water, ten to fifteen in the clearing bath, wash. Nothing is weighed, nothing is dissolved except the two clearing powders by the tablespoon, and nothing has a temperature.

Printing when you cannot judge an exposure any other way. The self-masking behaviour of a print-out process is real and the sheet leans on it correctly: “Images can be evaluated as they print. In most cases, the first print will be successful.” For a printer working with in-camera negatives of uncertain density range, or with a light source of unknown output, that is worth more than any published time would be.

Colour, deliberately and repeatably. This is the kit’s distinction and there is nothing else like it in the formulary. Purple and lavender at eight drops of gold to four of palladium; green and blue-black with gold and tungstate together; warm sepia from two drops of tungstate; blue-black to purple at the top of the gold range. The open print-out formula offers browns to neutral greys and nothing else, because it changes colour only by changing metal proportions and humidity.

Split-toned work, where two colours in one print is the intention. The sheet says it plainly — “You can have lots of fun with split tones!” — and gold in a palladium print-out sensitiser is one of the few places in alternative printing where two image metals genuinely deposit at different rates in different densities.

Where speed matters. “Ziatype is traditionally 2-3 stops faster than traditional developing out platinum and palladium.” That is the maker’s claim, unmeasured and plausible: a print-out palladium sensitiser at high humidity is a fast alternative-process material by any standard.

Not where the print must match one made from a different bottle. With no strength published for either of the two solutions that matter, there is nothing to calibrate against, and no way to tell a reformulated bottle from a fresh one except by printing.

Not in a dry room. The sheet is unusually firm about this and repeats it three times: at least 50 per cent relative humidity, and Sullivan’s own note asks for 50 to 65 per cent at 65 °F or above. A printer in a dry climate who ignores it will get warm, weak prints and will not know why.

Not as a way of learning what a Ziatype is made of. The kit names its chemicals, which is more than most, and then declines to quantify the two that matter. A student who reads only what comes in the box will be able to make the print and will not be able to describe the sensitiser.

When another formula is preferable

• When the sensitiser has to be reproducible from published numbers, Ware’s print-out platino-palladiotype is the same process with every strength stated: 60 per cent w/v ammonium iron(III) oxalate, 19 per cent w/v ammonium tetrachloropalladate(II), equal volumes, and a rule for why they are equal. The full comparison is under The nearest open formula below.
• When platinum is wanted rather than palladium, this kit cannot do it, and the reason is chemical rather than commercial: the lithium cation inhibits the print-out of platinum. Ware states it outright, and it is why no platinum bottle is offered for this process. The developing-out route is the three-solution drop system, and this course teaches palladium and not platinum in any case.
• When the question is what the original print-out process actually was, Pizzighelli and Hübl’s 1886 account is the ancestor everybody in this comparison is descended from, and the proportions are not these.
• When a developed print is what the work needs — deeper maximum density from a single coat, a developer that can be changed to change the colour — the Bostick & Sullivan platinum and palladium kits and the Photographers’ Formulary kits are the same supplier’s and its competitor’s developing-out boxes. Both are recorded at Level D for reasons this kit does not share, and the developer they use is Willis’s potassium oxalate.
• When more contrast is wanted, this course’s answer is not the bottle in the box. A dichromate is a chromium(VI) compound and the chromium ruling is that chromium(VI) is never used at any level, anywhere. The answers the course does give are a negative with a longer density range — which the sheet itself specifies at 1.35 to 1.50 — a duller light for proportionally longer, and gold, which is in the box, works in the same direction and is not a carcinogen.
• When the image metal should be silver rather than palladium, the kallitype sensitiser runs the identical iron photochemistry at a fraction of the metal cost, and Ware’s argyrotype is the modern print-out version of the same idea.
• When the room cannot be humidified at all, a developing-out process is the honest choice. Nothing in this box compensates for a dry room; the sheet’s own remedy is a humidifier, a kettle and water on the floor.

What the maker publishes

Three documents — a twelve-page instruction sheet, a kit listing and a set of listings for the individual bottles — and between them a great deal of procedure, a full colour chart, and two missing numbers.

Every chemical in the box, by name. “(1) 25 ml Lithium Palladium Solution / (1) 25 ml Ferric Ammonium Oxalate Solution (a.k.a Ammonium Ferric Oxalate, AFO, FAO) / (1) 25 ml 40% Sodium Tungstate / (1) 10 ml 5% Gold Chloride / (1) 25 ml 1% Ammonium Dichromate / (1) 250 gms EDTA clearing agent / (1) 250 gms Sodium Bisulfite (for clearing).” Three of the five solutions carry a percentage. Two do not.

A history, with attributions. “The Ziatype was developed in the Labs of Bostick & Sullivan in 1997. Richard Sullivan was looking for a better way to control color and contrast in a palladium or platinum/palladium printing system.” It credits Pizzighelli, and it credits Ware: “In the mid 1980’s, Dr. Michael Ware developed a variation of Pizzighelli’s POP process which has enjoyed a loyal but small following.” Then the claim this whole page turns on: “In the Pizzighelli and Ware versions, color and contrast are interlocked and controlled largely by humidity. In the Ziatype, the color and contrast are controlled chemically as well as in part by humidity, making a more controllable and flexible printing system.” A maker’s sheet that names its intellectual ancestors and argues for its own difference is rare enough to be worth noticing.

What each bottle is for, in a paragraph each. The lithium palladium is dark brown and does not oxidise or age; it must never be contaminated with the iron solution, and it must be kept in glass, “never metal as the palladium will plate out on the container”. The ferric ammonium oxalate is “the chemical in your emulsion mix that is sensitive to light”, green, good for two to three years. The tungstate “adds a warm tone to the print and also reduces contrast”. The gold “will increase contrast (increasing contrast always increases exposure time) and give you split tones”. The dichromate “increases contrast nearly twice as much as the gold does and gives a cooler tone print”. Every one of those is a functional statement rather than a chemical one, and every one is usable.

A colour chart with eleven starting points, credited to Richard Sullivan and Carl Weese, tabulated against six columns — ferric ammonium oxalate, lithium ferric oxalate, lithium palladium, cesium palladium, gold and sodium tungstate — with a stated colour and a stated contrast for each row. Twelve and twelve for neutral slate-grey black at low contrast; twelve of iron with four of palladium and eight of gold for purple and lavender at very high contrast; twelve and twelve with three of tungstate for very warm sepia at low contrast. This has no equivalent anywhere else in this formulary, and it is the single most useful thing in the box.

Coating volumes in drops, for four sizes. Ten to fifteen in total for a 4x5, fifteen to twenty for a 5x7, thirty to thirty-five for a 6x9, forty to forty-five for an 8x10.

A specification for the negative. “The negative should have a density range of 1.35 to 1.50. This will give a print with a full rich tonal range.” Named films and named developers for in-camera negatives — HP5, FP4, D-19, Rollo Pyro, Pyrocat-HD — and a pointer to an online guide for digital ones.

Two drying methods with a physical test for each. One-step: coat, wait two or three minutes, cool-air dry for about a minute, and check that the paper “should not crackle when snapped or bent back and forth gently but quickly. It should sound a little ‘dead’.” Two-step: dry it right out, then re-humidify over an ultrasonic humidifier for one to two minutes a side and listen for the crackle going dull. Both are judgements rather than measurements, and both are more concrete than most sheets manage.

A humidity range for the room, three times over. “The room needs to be around at least 50% humidity”, and Sullivan’s own working range is 50 to 65 per cent at 65 °F or above, with a candid paragraph about running a large humidifier at 7000 feet in Santa Fe and spraying water on the darkroom floor when Melody Bostick is not there to object.

An assembly order for the printing frame. “Glass, negative, mylar/acetate (if negative is not in Krystal Seal), coated paper, mylar/acetate, backing paper if needed, frame back”, with the reason: the coating is wet and must not touch the negative.

The exposure, as a comparison and an end point. No time for any named source, but “Ziatype is traditionally 2-3 stops faster than traditional developing out platinum and palladium”, a sun lamp taking about 3 to 8 minutes on a 4x5 negative, and dense negatives running half an hour or longer. Expose “until the print looks right, and there is the desired detail in your highlights. It will appear yellow in the highlights but over all the exposure will be correct.”

The whole of the wet processing. Two minutes in running water, poured fast enough to break the surface bubbles, never in a metal tray. Ten to fifteen minutes clearing, until no yellow remains in the highlights. A final wash. And a capacity: “Fresh clearing agent will clear up to a 20-25 8x10 prints.”

The papers. Bergger Cot 320, Arches Platine, Revere Platinum, Hahnemühle Platinum Rag and Japanese Kozo on the sheet; three of those five again on the store listing.

What is not disclosed

The strength of the lithium palladium solution. This is the first and largest gap and it is not a technicality. The maker manufactures the salt itself — “Lithium Palladium is manufactured in house by our chemist Dana Sullivan” — identifies it on a store listing as lithium chloropalladite, and publishes no concentration, no molarity, no formula and no CAS number for it anywhere. The comparison that makes the omission sharp is on the company’s own shelf: the classic developing-out bottle in the same 25 ml size is listed as “Sodium Chloropalladite 15% solution” with “One 25ml bottle equal to 625 drops of coating solution”. Two bottles, one supplier, one published in full and one not at all.

The strength of the ferric ammonium oxalate solution. The same omission on the other half of the sensitiser. The store listing for the bottle sold separately — “Ammonium Ferric Oxalate Sol. No. 1 Ziatype Solution No. 1” — gives no strength either. The only concentration anywhere near this material belongs to the 100 g of solid the company sells by the jar, which is a different object.

!Why two missing numbers matter more here than on any other page in this lane

On most bought-product pages an unpublished concentration costs the reader a comparison. Here it costs them the process.

The Ziatype’s published claim is that colour and contrast are chemically controlled, and the whole of that control is a table of drop counts: twelve drops of iron against twelve of metal, with the metal split between palladium and gold in whatever proportion the wanted colour needs. A drop count is a ratio of amounts of substance, and the sheet publishes only one side of it.

Work it through with what is published. The gold bottle is 5 per cent, and the store listing names the compound as hydrogen tetrachloroaurate(III) trihydrate, relative molecular mass 393.83. On the assumption that the percentage is weight in volume — which the maker nowhere states — that is 50 g/L, or about 0.13 molar. The dichromate at 1 per cent is about 0.04 molar on the same assumption. Both of those are this course’s arithmetic and are marked as such.

Now try the other side. The palladium bottle is n per cent of a compound whose formula is not printed. There is no number. So the one question the chart is built to answer — how many moles of gold am I putting against how many moles of palladium when I move from ten-and-two to four-and-eight — cannot be answered from anything the maker publishes, by anybody, including the maker’s own customers.

That does not make the chart useless: it is a table of starting points, it says so, and starting points work. It makes the chart unteachable. A printer can follow it and cannot reason about it, cannot scale it, cannot check a new bottle against an old one, and cannot compare it with the open formula that publishes both numbers.

What else is in the bottles. No humectant, no surfactant, no acid, no stabiliser and no preservative is either named or ruled out in any of the five solutions. The sheet’s own advice to add a drop of Tween 20 implies that no wetting agent is present, and never says so.

Any pH. Not for the iron solution, not for the palladium, not for the mixed coating solution, and not for the clearing bath — which is the one that matters most, because it is a bath in which an alkaline chelating salt and an acidic reducing salt are dissolved together and their combined pH decides what the chelate can hold. The only pH figure anywhere in the supplier’s documentation for anything in this box is on a substance sheet for the dichromate solid.

The identity of the clearing powder. The sheet in the box says “EDTA clearing agent” and stops. EDTA is sold as at least four different salts with solution pH values from about 3 to about 10 and different affinities for iron in its two oxidation states, so the name alone does not identify the substance. The maker’s own store listing calls the 250 g packet “EDTA Tetra Sodium (B+S Clearing Agent)” and its library holds exactly one EDTA sheet, for EDTA Tetrasodium Salt at CAS 13235-36-4. This page therefore reads the powder as the tetrasodium salt, and marks that as an identification made from the maker’s other literature rather than from anything in the box. The disodium EDTA entry records the ambiguity from the other side.

The drop volume. Five droppers are supplied and no volume is given for any of them. That has three consequences at once: the drop table cannot be converted to millilitres, the kit’s coverage cannot be calculated, and the dose of any additive cannot be stated as a weight.

The yield. No figure at all — not in the instructions, not on the kit listing, not on any listing for any of the bottles. Every other kit in this formulary claims a number of prints. This one does not.

Any exposure time for a named source. A sun lamp on a 4x5 negative is the only figure, and “sun lamp” is not a specification. The kit is sold for use with a UV bank, UV CFL bulbs or the sun, and no time is attached to any of them.

Any sensitometry. No exposure scale, no density range for the print, no maximum density, no speed, no reciprocity note, no curve. The sheet quantifies the negative and never the paper.

Which contrast agent the current kit actually depends on. The company sells “Ammonium Ferric Oxalate Solution #2 — Formerly Ziatype Sol. No. 2”, whose listing carries the field “Chem Formula Cont. Pot. Chlorate” and the sentence “We prefer using drops of Ammonium Dichromate solution now”. So the contrast route in this system used to be a chlorate dissolved in the iron bottle and is now a dichromate counted in by drops. The change is documented on a store page and appears nowhere in the instruction sheet.

!No safety data sheet exists for anything in this box

Bostick & Sullivan maintains a safety data sheet library on its own site. It is not thin: eighty-nine sheets, enumerated in full for this course through the site’s own data endpoint. Every one of them is a single-substance sheet for a chemical the company sells loose by the jar or the bottle, several of them republished from Spectrum, LabChem, Fisher and Univar rather than written by the company.

For this kit the gaps are specific, and they are the two that matter:

• There is no sheet for the Ziatype kit, or for any premixed solution the company sells.
• There is no sheet anywhere in the library for gold chloride, in any form, although the company manufactures it in house, sells it in four strengths and puts 10 ml of it in this box.
• There is no sheet anywhere in the library for any chloropalladite — lithium, cesium or sodium. The nearest is a Fisher Scientific sheet for palladium(II) chloride, a red solid sold by the gram, which is the raw material rather than the product.

The library does hold sheets for the ferric ammonium oxalate, the sodium tungstate, the ammonium dichromate, the EDTA and the sodium bisulfite, and those are read below. Four of the five describe solids the company sells by the jar, not the solutions in the kit. Only the EDTA sheet describes an item in the form the box actually ships it.

The consequence is exact: the Safety section below is assembled from substance sheets, from this course’s own classification rubric and from the chemical encyclopaedia. It is not a manufacturer’s assessment of the liquids in the bottles, because no such assessment has been published.

Disclosed components

Seven, and the disclosure is unusually uneven: two components with a name and no number, three with a name and a number, and two powders for which the maker files a proper sheet. The hazard column is populated only for the dichromate and the EDTA, and the reason is worth stating once. The company’s sheets are American in format and give their classifications either in words or in H numbers according to their vintage; where a sheet prints H numbers they are reproduced, where it gives GHS categories and statements they are matched to their codes, and where it prints only loose sentences those sentences are quoted below rather than translated, because turning “Slightly hazardous in case of skin contact (irritant)” into a code would be an inference dressed as a citation. Every classification below is for the substance, not for the solution in the bottle.

Lithium Palladium Solution, 25 ml, strength not published. The image metal, and the least documented thing in this formulary that a reader is actually asked to buy. The only identification the company makes is on a store listing whose entire text is “Lithium Chloropalladite solution. Standard for Ziatype.” — so the compound is the lithium analogue of the potassium and sodium tetrachloropalladates the course has pages for. No strength, no formula, no molarity and no CAS number are printed anywhere, and there is no safety data sheet for it. What the instruction sheet does give is a set of handling facts worth having: it is dark brown; it “will last almost indefinitely” and “does not oxidize or age”, which is a strong and unusual keeping claim; refrigeration is unnecessary; it must never be contaminated with the ferric ammonium oxalate; and it must be kept in glass, “never metal as the palladium will plate out on the container” — a real electrochemical warning, correctly given, since palladium(II) is reduced by most base metals on contact. The nearest hazard document in the company’s library is the Fisher sheet for palladium(II) chloride, classified corrosive to metals Category 1, serious eye damage Category 1 and skin sensitisation Category 1, signal word Danger. That sheet describes the raw material, not the bottle, and this page cites it as the nearest thing rather than as the thing.

Ferric ammonium oxalate solution, 25 ml, strength not published, CAS 13268-42-3 for the solid. The other half of the sensitiser and the only photosensitive substance in the box, which the sheet states correctly and in its own words: “Ferric Ammonium Oxalate is the chemical in your emulsion mix that is sensitive to light.” Green, and stated to last two to three years. The maker’s own substance sheet is Spectrum Chemical F1002 of 12 January 2016 and it is worth reading for three things. Its classification is heavier than the material’s photographic reputation would suggest — Acute toxicity Oral Category 4 and Dermal Category 4, Skin corrosion/irritation Category 2, Serious eye damage/eye irritation Category 2 and STOT single exposure Category 3, signal word Warning, with the statements “Harmful if swallowed”, “Harmful in contact with skin”, “Causes skin irritation”, “Causes serious eye irritation” and “May cause respiratory irritation”, and the storage instruction “Store locked up”. Its section 11 is a blank: every acute-toxicity field on the sheet reads “No information available”, so the classification rests on read-across rather than on a measured LD50. And its incompatible materials are oxidising agents and strong acids — a fact with no consequence until you notice that the same box contains a dichromate, which is an oxidising agent, and that the clearing bath is acidified with a bisulfite. Elsewhere it gives the trihydrate formula, formula weight 428.07, density 1.78 at 17 °C, decomposition at 167 to 170 °C, very soluble in water, no pH, “Not considered carcinogenic”, and the same odd chronic note that appears on the company’s citrate sheet: prolonged eye contact may cause a brownish discoloration of the eyes. The company files this one sheet twice, under Ammonium Ferric Oxalate and again under Ferric Ammonium Oxalate; the two library entries resolve to byte-identical copies of the same file.

Sodium tungstate, 25 ml at 40 per cent, CAS 10213-10-2. The warm-tone additive, and the only thing in the box that lowers contrast. The course has no encyclopaedia page for it, which is itself worth recording: sodium tungstate appears in no other formula in this formulary. The maker’s own document for it is not a safety data sheet at all but a pre-GHS material safety data sheet from Spectrum Laboratory Products, undated, in the old sixteen-section American format, filed in a library whose index admits that “Some chemicals still only have the MSDS but we are working on updating them as we get the SDS.” Its entire hazard identification reads “Slightly hazardous in case of skin contact (irritant), of eye contact (irritant), of ingestion, of inhalation”, with carcinogenic, mutagenic, teratogenic and developmental effects all recorded as “Not available” — and then section 11, several pages later, says the substance “May affect genetic material” and “May cause adverse reproductive effects based on animal data. Animal studies showed post-implantation mortality effects on fertility.” A sheet that says a substance’s mutagenic effects are unknown in section 3 and that it may affect genetic material in section 11 is not a document to navigate by, and the ACGIH limit it quotes — 5 mg of tungsten per cubic metre, 10 short-term — is the one number on it that can be relied on. Its physical section gives molecular weight 329.86 and “soluble in about 1.1 parts of water”, which is about 48 per cent by weight; on this course’s arithmetic the maker’s 40 per cent stock is therefore not far from saturated, which is consistent with its being a bottle that should not be allowed to get cold. And there is a small documentary curiosity in the store listing for the solid, which prints the name Sodium Tungstate Dihydrate, the CAS number of the dihydrate and the formula weight of the dihydrate, and then prints the formula as “Na2WO4.5H2O”.

Gold chloride, 10 ml at 5 per cent. The split-tone additive, and the component with the widest gap between what it does and what is documented about it. The compound is named in exactly one place in the company’s literature — the store listing for the same bottle, “5% Gold Chloride Solution – Hydrogen Tetrachloroaurate (III) Trihydrate” — and the safety data sheet library contains no sheet for gold chloride in any form, although the company makes it in house and sells it at 0.2, 1, 5 and 10 per cent. No CAS number is printed for it anywhere, which is why the table above carries none. What the maker does say is functional and correct as far as it goes: gold “will increase contrast (increasing contrast always increases exposure time) and give you split tones”, and the colours available depend on the ratio to palladium and tungstate. It is used by replacing part of the palladium, not by adding to it, which is the one place in the whole system where the maker states a rule rather than a starting point. The chemistry behind why gold works here and not in a platinum sensitiser is Ware’s and is set out under The mechanism; so is his caution that gold(III) attacks free oxalate, which is the reason a Ziatype mixture containing gold should be coated at once. The course’s own encyclopaedia entry for the gold(III) chloride that photographers also call “gold chloride” is the place to check which compound a formula means. Note also that the sheet forbids one combination and gives no reason: “Gold Chloride cannot be used with Cesium Palladium.”

Ammonium dichromate, 25 ml at 1 per cent, CAS 7789-09-5. The contrast agent, and the one component of this kit that this course will not use. The maker’s own note is the strongest safety statement in the kit’s entire literature and deserves quoting in full: “Ammonium Dichromate is a dark orange color and has a shelf life of approximately 5 years. It darkens in color over time. It is a known carcinogenic, ALWAYS wear gloves when working with this chemical. Ammonium Dichromate increases contrast nearly twice as much as the gold does and gives a cooler tone print. Use sparingly, one drop will go a long way. Has been noted to increase grain and exposure time.” That is a manufacturer naming a carcinogen in its own kit sheet, in bold, and it is more than most manage. The company’s substance sheet, Spectrum Chemical A1179, is the longest classification anywhere in its library: Carcinogenicity Category 1A, Germ cell mutagenicity Category 1B, Reproductive toxicity Category 1B, Acute toxicity by inhalation Category 2, Skin corrosion Category 1, Serious eye damage Category 1, respiratory and skin sensitisation Category 1, STOT repeated exposure Category 1 and Oxidizing solids Category 2, signal word Danger, with “Fatal if inhaled”, “Causes severe skin burns and eye damage”, “May cause cancer”, “May cause genetic defects”, “May damage fertility or the unborn child” and “May intensify fire; oxidizer”. Its ACGIH limit is 0.0002 mg/m³ as chromium, the tightest exposure limit anywhere on this page. Its oral LD50 in the rat is 48, 53 and 80 mg/kg across three studies; its four-hour inhalation LC50 is 0.156 mg/L; IARC lists it Group 1, carcinogenic to humans, as chromium(VI). None of that applies at full strength to a 1 per cent solution, and the dilution is doing real work — but the chromium ruling turns on the oxidation state and not on the concentration, and the ruling is that chromium(VI) is never used, at any level, anywhere. This course gives no procedure for this bottle. What to do with it instead is under Safety and Waste. The same ruling puts potassium dichromate and the potassium chlorate of the superseded Ziatype Solution No. 2 out of use as well, by two different routes.

EDTA clearing agent, 250 g, CAS 13235-36-4 at 95 to 100 per cent. The chelating half of the clearing bath, and one of only two lines in this table for which the company publishes a sheet describing the thing in the box. That sheet is VWR/Amresco 0245, revision 3 of 29 September 2016, for EDTA Tetrasodium Salt, and it classifies the powder Acute toxicity Oral Category 4, Acute toxicity Inhalation (Dusts/Mists) Category 3, Skin corrosion/irritation Category 2, Serious eye damage/eye irritation Category 2 and STOT single exposure Category 3, signal word Danger, with H302, H315, H319 and H331 — the last of which is toxic if inhaled, printed against a store listing that calls the same powder a “safe, easy to use clearing agent”. The two statements are not compatible and the sheet is the one to believe: this is a fine alkaline powder that should not be raised as dust. The chemistry of what it does is on the disodium EDTA page, on the page for its dihydrate and in the platinum clearing sequence, and the salt matters: a tetrasodium solution is alkaline at around pH 9 to 10, which is where EDTA binds iron(II) best, while iron(III) is best held near pH 3 to 4.

Sodium bisulfite, 250 g, CAS 7681-57-4 at 97 per cent or more. The reducing half of the same bath, working alongside the EDTA rather than after it. The kit labels it sodium bisulfite; the CAS number the maker prints beside that name on its own store listing, and the sheet it files for it, are both sodium metabisulfite’s, which is the ordinary commercial situation and is worth knowing when you come to buy a replacement. The sheet is Esseco USA EUSA-120, published by the supplier as a page-image scan with no text layer at all, classifying it Acute Toxicity Category 4 oral and Eye Damage Category 1, signal word DANGER, and carrying two warnings that belong in a darkroom rather than a factory: it “reacts with acids to form toxic and irritating sulfur dioxide gas”, and it “may cause severe and possibly fatal allergic reactions if inhaled or swallowed by some asthmatics and other sulfite-sensitive individuals”. Where a clearing sequence wants a sulfite rather than a bisulfite the difference is pH, and the iron-silver clearing sequence sets it out.

Behaviour

The image is finished before the frame is opened. This is the defining property of a print-out process and the sheet is right to lead with it: “A POP process, i.e. printing out system. Images can be evaluated as they print. In most cases, the first print will be successful. Far fewer underexposed or overexposed prints.” The palladium is reduced to metal in the paper during the exposure, so what comes out of the frame is the picture and not a latent version of it.

It is self-masking, and that is why the negative specification is loose. As the shadows build, the metal already deposited absorbs the printing light, so those areas slow down while the highlights continue. A print-out process therefore tolerates a negative whose density range would block up on a developed paper. The sheet still asks for 1.35 to 1.50, which is a sensible target rather than a requirement.

Wet paper prints cool; dry paper prints warm. The sheet says this four separate times in four different forms of words — “This will make a nice cool neutral black print while the emulsion is wet. If the paper dries out, you will get a warmer tone print”, and at step 5, “Wet emulsion=cool tone, dry emulsion=warm tone”. It is the single most important behavioural fact about the process and it is entirely reproducible: it is a particle-size effect and the mechanism is set out below.

Humidity is not a refinement here, it is the operating condition. “The Ziatype process depends on humidity in the paper to allow the development to occur during the exposure.” Below about 50 per cent relative humidity in the room the sheet says the coated sheet will dry out before it has finished printing; Sullivan’s own working range is 50 to 65 per cent at 65 °F or above. A printer who reads nothing else in this entry should read that.

The wetness that makes it work is also what damages contact. The sheet is unusually honest here: the acetate sandwich exists because the coating is wet, and “due to the necessity of the paper needing to be wet and the use of acetate sheets while exposing, that fall out spots or blurry spots in your print are much more common. The paper is basically drying and moving while exposing.” Extra backing paper is recommended to force contact. This is the same cost Ware identifies from the other direction — a lithium sensitiser has to be brought to a state of wetness “which is uncontrolled and liable to damage negatives in contact, unless a thin plastic film is interposed between them”, and which “can degrade the image sharpness.”

Gold slows it down, and the maker says so. “Increasing contrast always increases exposure time” is printed in the middle of the gold paragraph, and it is a real and useful observation: gold(III) is an oxidant sitting in the sensitiser, and part of the photoproduct is spent on it.

The dichromate adds grain, on the maker’s own account and on Ware’s. The kit sheet says ammonium dichromate “increases contrast, grain, and exposure time”; the Platinomicon says the addition of “potassium chlorate or dichromate to the platino-palladiotype can cause ‘graining’ and truncation of the tonal scale”. The maker and the independent authority agree, having reached the observation from different directions, and the agreement is worth more than either statement alone.

The bath is not a developer and cannot be exhausted. The two minutes in water dissolve the unused iron and palladium salts and stop the print-out; the clearing bath removes what the water leaves. Nothing is reused: the coating is one-shot and the clearing bath is thrown away at the end of the session on the sheet’s own instruction.

Speed, comparatively. “Ziatype is traditionally 2-3 stops faster than traditional developing out platinum and palladium.” No absolute figure exists, and given three light sources, an unstated palladium strength, the paper and the humidity of the room, a published time would be a fiction.

Image characteristics

Colour: the widest published range in this formulary, and the reason to own the box. Neutral slate grey-black from palladium alone; warm brown from cesium palladium; cool and very cool as gold replaces two and four drops of the twelve; purple and lavender at eight drops of gold to four of palladium; green and blue-black with gold and tungstate together; slightly and very warm sepia at two and three drops of tungstate; red-warm from lithium ferric oxalate. Nothing in that list is a measurement — no colour coordinates, no spectra, no reflection densities — and three of the eleven rows need a bottle the kit does not contain. The Getty atlas’s independent account confirms the kind of control without quantifying it either: tonality here is chemical, and tungsten, gold and caesium are detectable in the finished print by XRF.

Contrast: directional, never numbered. Gold up, dichromate up about twice as much, tungstate down. No exposure scale, no gradient and no step-tablet count is published for any of them, so a printer who wants to know what “very high contrast” means on the chart has to print it. The one quantified contrast statement on the sheet is about the negative — 1.35 to 1.50 — and it is the right place to put it: the honest contrast control in a self-masking print-out process is the negative, which is Ware’s conclusion as well.

Tonality: long, and long by construction rather than by adjustment. A print-out process delivers its scale by self-masking, and the sheet’s whole exposure instruction depends on it: keep going until the highlights have the detail you want, and trust the shadows not to fill in. No maximum density is published; the sheet’s only claim is that the right amount of emulsion and the right exposure “will give you a beautiful dmax”, which is an aspiration rather than a figure.

Surface and support: matte, no binder, and the paper is specified. Metal nanoparticles among the cellulose fibres with nothing over them, on 100 per cent rag with “a fairly hard surface”. The five recommended papers are named, and the sheet’s advice against Tween 20 on Arches Platine sits awkwardly beside its recommendation of Arches Platine.

Identification, from the museum side. The Getty atlas is blunt: a Ziatype has no unique visual, microscopic or analytical signature separating it from any other palladium print. XRF finds palladium and residual iron; the additives are what give it away. “Only when potassium dichromate is used to adjust the contrast of the final print can a very small amount of chromium be detected” — and note that the atlas says potassium where this kit ships ammonium, which does not change the element XRF sees. Tungsten, gold and caesium may also be found, and finding them together with palladium and iron “may represent strong evidence that the analyzed photographs are Ziatypes”. A colour system built out of extra elements leaves a signature made of extra elements, which is a pleasing consequence and one a conservator will meet before a printer does.

The mechanism

Almost everything in this section is inference, and the boundary is worth marking before it starts. The maker makes exactly three chemical statements about this kit: that the ferric ammonium oxalate is the light-sensitive component; that palladium will plate out on a metal container; and that the palladium compound is a lithium chloropalladite, on a store listing. Everything else below is the open literature applied to those names and to the published percentages, and every step of it is an inference from what the maker publishes rather than an account the maker gives.

⚗What the two unquantified bottles do

Light reduces the iron, and an oxalate ligand pays for it. All the photochemistry belongs to the trisoxalatoferrate(III) anion. Ultraviolet reduces iron(III) to iron(II) at the expense of one oxalate ligand, which is oxidised to two molecules of carbon dioxide:

hv + 2 [Fe(C₂O₄)₃]³⁻ → 2 [Fe(C₂O₄)₂]²⁻ + C₂O₄²⁻ + 2 CO₂

The photolysis: iron(III) on the left, iron(II) on the right

The iron(II) then reduces the palladium, in place, during the exposure. Two iron(II) ions give up one electron each and one palladium(II) becomes an atom of metal:

2 [Fe(C₂O₄)₂]²⁻ + [PdCl₄]²⁻ → 2 [Fe(C₂O₄)₂]⁻ + Pd + 4 Cl⁻

Two iron(II) per atom of palladium

That reaction needs the ions to move, and ions move only in water. This is why the whole kit is organised around humidity: the water in the paper fibres is the solvent in which the reduction happens, and if it is not there the reduction waits for a developer instead. The maker’s version of this is the sentence “The Ziatype process depends on humidity in the paper to allow the development to occur during the exposure”, which is correct and unexplained.

The wash is not a developer. Two minutes of running water carries away the unreacted iron and palladium salts. The clearing bath then removes the iron the water could not, which is what the yellow highlight stain is made of.

⚗Why wet paper prints cool and dry paper prints warm

The image substance is palladium in particles of a few tens of nanometres, and the colour of a nanoparticle metal is a function of its size. Ware sets it out directly: a large reservoir of fibre water lets more substance react locally during the exposure, so the metal particles grow larger and the image appears more neutral; a restricted pool of water constrains the chemistry to small particles, which look brown or sepia for palladium — and pink, magenta or blue for gold.

So the sheet’s repeated “wet emulsion=cool tone, dry emulsion=warm tone” is not a rule of thumb. It is the particle-size argument arriving at the bench, and it is the same effect Ware measures across a humidity series: a palladium sensitiser goes from red-brown at 32 per cent relative humidity, through purplish-brown at 55 per cent, to a neutral grey-black at 80 per cent and above.

Two things follow that the kit sheet does not say. First, the sheet’s crackle test is a proxy for a number that can be measured: a constant-humidity enclosure over a saturated salt solution holds a known relative humidity, and Ware tabulates them — ammonium chloride at 80 per cent, common salt at 76, calcium nitrate at 55, potassium carbonate at 44. Second, temperature matters for the same reason humidity does, because it is absolute water content that governs: 56 per cent RH at 25 °C carries the same water as 75 per cent at 20 °C. Sullivan’s instruction to run the room at 65 °F or above is that fact, found empirically and stated without it.

⚗What the gold is doing, and why the same trick fails with platinum

Gold in this kit is not a toner applied afterwards. It is a second image metal dissolved in the sensitiser, and it is there for two reasons at once.

It is reduced alongside the palladium and gives its own colours. Gold nanoparticles are among the very few metals with a surface plasmon absorption in the visible, which is why they can be pink, magenta or blue where palladium can only be brown or grey. That is the whole physical basis of the chart’s purples and lavenders, and of the split tones: two metals depositing at different rates in different densities give two colours in one print.

It is also an oxidant, which is why it raises contrast and exposure time. Ware gives the redox potentials that decide whether a mixed sensitiser is stable at all. With platinum it is not:

2 [AuCl₄]⁻ + 3 [PtCl₄]²⁻ → 3 [PtCl₆]²⁻ + 2 Cl⁻ + 2 Au

Gold(III) oxidising platinum(II) before the paper is even coated

Gold(III) at +1.00 V against platinum(II)/(IV) at +0.68 V means the gold is reduced to metal in the bottle, fogging the paper lilac and doing nothing useful. With palladium the couple runs the other way: palladium(II)/(IV) sits at +1.288 V, above gold’s +1.00, so a mixed gold-palladium sensitiser is stable and “may be used as a sensitizer”. This is a real and non-obvious piece of chemistry and it is why gold is offered in a palladium kit and in no platinum one.

But gold(III) does attack the free oxalate, and Ware’s caution applies directly to a shot glass of this kit’s mixture:

2 [AuCl₄]⁻ + 3 C₂O₄²⁻ → 2 Au + 8 Cl⁻ + 6 CO₂

Gold(III) consuming free oxalate in the dark

which is the mechanism behind his instruction that the coating and drying be “carried out rapidly” and the ambient temperature kept down. The kit sheet publishes no keeping time for the mixed solution at all, and this is the reason it should have one. Coat what you count out, and count out only what you will coat.

And the sodium tungstate, which this course cannot explain. The maker says it adds warmth and reduces contrast, and repeats it on the store listing. Nothing this course has read explains why. The Platinomicon does not mention tungstate anywhere in its 350 pages; the Getty atlas records tungsten as an XRF signature and offers no mechanism; the twenty factors Ware lists as governing image colour in a platinum-palladium print do not include it. Two readings are available and this page endorses neither. A tungstate at 40 per cent is a strongly hydrated anion and might plausibly act as a humectant — except that a humectant should make the sheet wetter and therefore cooler, so that reading has the sign wrong unless the effect is on ion mobility rather than on water content. Alternatively it may be an adsorbate on the growing metal particle, which is the third of Ware’s four physico-chemical determinants of image colour and the one for which surfactants are the worked example. Both are speculation, they are recorded as speculation, and the honest statement is that the best-quantified additive in this box is the one whose mechanism nobody has published. See Experiments.

🧮What can be calculated from the maker's numbers, and what cannot

Every figure in this box is this course’s arithmetic on the maker’s published percentages, and every one additionally assumes that the unlabelled percentages are weight in volume, which the maker nowhere states.

The gold. 5 per cent of hydrogen tetrachloroaurate(III) trihydrate, relative molecular mass 393.83, is 50 g/L, or about 0.13 molar.

The dichromate. 1 per cent of ammonium dichromate, formula weight 252.10, is 10 g/L, or about 0.04 molar.

The chromium in one drop. Taking the maker’s own drop figure from a different bottle — 625 drops to 25 ml, so 0.04 ml a drop — one drop of the 1 per cent dichromate carries about 0.4 mg of the salt and therefore about 0.17 mg of chromium, every atom of it chromium(VI) at the moment it goes onto the paper. Two drops on one 8x10 is about a third of a milligram. That is a small quantity and it is enough to be found later: the Getty atlas records that chromium is detectable by XRF in exactly this situation.

The palladium. Cannot be calculated. There is no published strength, no published formula and no published molarity for the lithium chloropalladite, and none for the ferric ammonium oxalate solution either. So the iron-to-palladium ratio, the gold-to-palladium ratio and the metal loading per square inch are all unavailable — the three numbers that would let this chart be reasoned about instead of merely followed.

The coverage, if the drop figure holds. At 20 drops of each solution per 8x10 and 0.04 ml a drop, each 25 ml bottle carries about 625 drops and therefore about 31 prints at 8x10. That is this course’s arithmetic on a drop volume the maker publishes for a different bottle, and it should be treated as an order of magnitude rather than a yield. The maker publishes no yield for this kit at all.

The tungstate against its own solubility. The supplier’s MSDS says sodium tungstate dihydrate is “soluble in about 1.1 parts of water”, which is about 48 per cent by weight. A 40 per cent stock is therefore close to saturated, which is a reason to keep the bottle warm and to look at it before using it after a cold night.

!The disagreement about the cation, and which side this course takes

The maker and the most-cited independent authority on these processes disagree in print about the central design choice of this kit, and both statements are quoted rather than averaged.

What the maker says. The instruction sheet, page 2: the Ziatype “uses lithium (or cesium) palladium chloride as the primary metal and ferric ammonium oxalate for the iron compound. In the Pizzighelli and Ware versions, color and contrast are interlocked and controlled largely by humidity. In the Ziatype, the color and contrast are controlled chemically as well as in part by humidity, making a more controllable and flexible printing system.”

What Ware says. The Platinomicon, section 4.2: the process “strongly resembled the printing-out platinum-palladium method that had been published twelve years earlier in the UK, but with the difference that some of the ammonium cation was replaced by lithium or caesium cations, based on the erroneous supposition that these cations would serve to control the humidity of the sensitizer.” And in section 11.13 he gives the argument. A hygroscopic cation does not help print-out, because the water it attracts is bound in its own hydration sphere and is not available as a solvent for anything else; lithium is “one of the worst cations in this respect”, since it must take up a large quantity of water in a secondary sphere before any is free to mobilise other ions. Ammonium is a structure-breaking cation that absorbs water in a disordered state without binding it strongly, so “only a relatively small amount of water need be absorbed to provide sufficient ion mobility to enable a print-out process.” His conclusions are specific and checkable: lithium “will totally inhibit the print-out process” in a pure platinotype sensitizer; with palladium and gold the cations can be used “but high degrees of hydration may be called for, with increased risk to the negative”; and caesium forms salts of low solubility, requiring hot or supersaturated solutions that then crystallise.

Where the evidence sits. Ware’s argument is thermodynamic and its premises are measurable — the two enthalpies of solution he quotes, −37.2 kJ/mol for lithium chloride and +15.2 for ammonium chloride, are textbook values, and the consequence he draws from them is the one this course teaches on the lithium chloride page. It also predicts, correctly, three things this kit displays: that it is a palladium-only process; that it needs an unusually wet sheet; and that the wet sheet endangers the negative, which is exactly why the kit ships a procedure built around acetate sandwiches. The maker’s claim is different in kind and is not contradicted by any of that: the Ziatype’s colour and contrast really are chemically controlled, and the Getty atlas independently describes it in those terms.

So the course’s position is that both are right about different things. The chemical colour control is real and is this kit’s genuine contribution. The rationale offered for the lithium cation is, on the published physical chemistry, wrong — and the practical cost of the choice is visible in the sheet’s own three pages about humidity and its own warning about blurred prints. A printer who wants the colour chart buys the lithium; a printer who wants the driest workable sheet and the safest contact uses the ammonium salt of the open formula. What nobody has published is a measurement of the difference, and that is the experiment this page most wants done.

The nearest open formula

Ware’s print-out platino-palladiotype, and the comparison is unusually direct because the kit’s own instruction sheet names it.

The same process, from the same ancestor. Both coat an ammonium iron(III) oxalate sensitiser with a soluble palladium(II) salt, humidify the sheet, expose to completion by inspection under a negative, develop in plain water and clear with EDTA and a sulfite. Both descend from Pizzighelli by way of the 1980s. The kit sheet says so and credits Ware by name, which is more than most competitors would.

The iron solution: 60 per cent w/v, against nothing. Ware publishes ammonium iron(III) oxalate trihydrate at 30 g made up with 33 cc of water to 50 cc — 60 per cent w/v, 1.40 molar, pH about 5, emerald green, and a note that the beaker goes cold as it dissolves, because that endothermic hydration is the very effect the process depends on in the paper. Bostick & Sullivan publishes the words “Ferric Ammonium Oxalate Solution”. There is nothing to compare.

The palladium solution: 19 per cent w/v of a named ammonium salt, against an unquantified lithium one. Ware makes his in the beaker from 1.8 g of ammonium chloride and 3 g of palladium(II) chloride to 25 cc, and publishes the result as 19 per cent w/v, 0.67 molar, pH about 2, stable indefinitely. The kit’s is bought made up, is lithium chloropalladite, and carries no number of any kind. This is the difference that propagates into everything else on this page.

The mixing rule, which the open formula has and the kit does not. Ware’s rule is that the volume of iron solution must always equal the combined volume of platinum plus palladium, and the two metals may be combined in any proportion inside that. At his published strengths that is about 2.1 iron(III) ions for every metal(II) ion, and the reduction consumes two. The kit’s chart follows the same rule without stating it — ten of its eleven rows put twelve drops of metal against twelve of iron, with gold replacing palladium — and the eleventh row breaks it, giving eleven drops of lithium palladium with six of gold, which is seventeen drops of metal against twelve of iron. Whether that row is a typographical error or a deliberate excess cannot be told from anything published, and the sheet’s own text says gold replaces palladium.

Humidity: measured against judged. Ware humidifies in a constant-humidity enclosure over a saturated salt solution for not less than half an hour, and publishes a table of salts and the relative humidities they hold. The kit dries with a fan or a hair dryer and tests by snapping the paper and listening. Both work; only one of them is a number, and only one of them can be written down and repeated in a different climate.

Clearing: three baths in an argued order, against one bath with three published strengths. Ware’s sequence is disodium EDTA at pH 3 to 4, which is optimum for complexing iron(III); then a sulfite bath, which reduces the residual iron(III) to iron(II); then tetrasodium EDTA at about pH 9, which is optimum for complexing iron(II) and leaves the paper alkaline. The order is the argument. The kit dissolves an alkaline tetrasodium EDTA and an acidic bisulfite in the same tray and gives the mixture three different strengths in three places on one sheet. On this course’s reading of the two salts’ published pH behaviour, mixing them puts the bath somewhere in the middle of the range where neither chelate is at its optimum, which would be consistent with the sheet’s own remedy of more concentration or more time — and that reading is an inference from the sheet’s chemistry, not a claim the maker makes or a measurement anybody has published.

What the kit adds. Five bottles already made up. Five droppers. An eleven-row colour chart with stated colours and stated contrast, which has no equivalent in the open literature. A route to purple, lavender, blue and green split tones that the open formula does not offer at all. And a procedure sheet that is better than Ware’s own in two specific places: it publishes coating volumes for four print sizes, and it publishes an assembly order for the printing frame.

What the open formula adds. A published strength for every solution, so the sensitiser can be reproduced next year and its ratios can be checked. A reason for every choice, including the choice of cation. A humidity method that is a number rather than a sound. A clearing sequence whose order is argued from the pH at which each chelate forms. And a stated stoicheiometry, so a printer can tell whether a mixture is metal-rich or iron-rich before coating it.

Safety

⚠Level B, and the one bottle that is not used at all

This kit sits at Level B on the classification rubric, and a level is assigned to a procedure rather than to a substance. The procedure here is a hand-coated palladium print-out sheet with an ultraviolet exposure and a clearing bath — the same procedure as the open print-out formula, which is also Level B, and the same as the print-out platino-palladiotype process page. It is not at Level D, and the difference from the two developing-out kits in this formulary is worth stating precisely: there is no platinum in this box, and there is no chlorate.

But there is a dichromate, and the course does not use it. The 25 ml of 1 per cent ammonium dichromate is a chromium(VI) compound. The chromium ruling is that chromium(VI) is never used, at any level, anywhere, and it turns on the oxidation state rather than on the concentration. So the bottle is not opened. It is labelled, kept upright, kept away from the other four, and disposed of through the route under Waste. Nothing on this page gives a procedure for it, and the contrast it offers is available from the gold bottle in the same box and from a longer-scale negative.

Required PPE for everything else in the box:

• Nitrile gloves throughout, as the sheet itself demands in capitals — see glove selection. The palladium solution stains skin and the iron solution is a skin irritant on its own maker’s sheet.
• Splash goggles when pouring the concentrates, on the strength of the ferric ammonium oxalate sheet’s Serious eye damage/eye irritation Category 2 and the EDTA sheet’s Category 2.
• A dust mask for the two clearing powders. The EDTA sheet carries H331, toxic if inhaled, and both powders are fine. Add them to water; do not tip them from a height.
• Eye protection against the ultraviolet source, and the ordinary discipline of UV unit operation.
• Normal room lighting is not enough. Coat under dim lighting with no ultraviolet and dry in the dark; the sheet’s reason is fogging that “may compress the midtone values”, which is a real sensitometric consequence stated without the word.

The hazard the sheet raises that most kit sheets do not. “When using a hair dryer to dry your paper, tiny particles of emulsion may be blown into the air. If inhaled, the dust could be harmful. It is advised to wear a dust mask when drying prints with a hair dryer.” That is a genuine and specific warning about a step the same sheet then recommends twice, and it deserves obeying: the emulsion being aerosolised contains an iron oxalate and a palladium salt, and if the printer has added the dichromate it contains chromium(VI) as well.

Ferric ammonium oxalate is harmful by two routes, on its own maker’s sheet. Acute toxicity Oral Category 4 and Dermal Category 4, “Harmful if swallowed”, “Harmful in contact with skin”, “Causes skin irritation”, “Causes serious eye irritation”, “May cause respiratory irritation”, and “Store locked up”. That is a heavier classification than most photographers expect of a mild green salt, and the sheet reaches it without a single measured LD50 — every acute-toxicity field on it reads “No information available”. Splashes get flushed; see first aid.

Oxalate is oxalate. The anion is a systemic poison in quantity and this kit contains a good deal of it in complexed form. Nothing here is a mouth-pipetting operation and nothing goes near food; see oxalic acid for what the ion does, and ferrous oxalate for the photoproduct’s insoluble cousin, which is what appears when a ferric oxalate rather than an ammonium ferrioxalate is used.

Palladium is the one metal in the box with no hazard document at all. No sheet for the lithium chloropalladite, no classification, no exposure limit. The nearest published document is the Fisher sheet for palladium(II) chloride, which classifies it a skin sensitiser, Category 1 — and skin sensitisation is the hazard gloves actually prevent, so the gloves are not optional even though the solution looks like weak tea. Unlike its platinum congener, potassium tetrachloroplatinate(II), palladium carries no tight airborne limit, which is one reason this course prints palladium and not platinum.

Sodium bisulfite plus acid gives sulfur dioxide. The Esseco sheet says so directly, and adds the warning that matters in a shared space: sulfite “may cause severe and possibly fatal allergic reactions if inhaled or swallowed by some asthmatics and other sulfite-sensitive individuals”. Nothing acidic goes into the clearing bath or into the container it is poured from. See incompatibilities.

The EDTA powder is toxic if inhaled and is sold as safe. The sheet’s H331 against the store listing’s “safe, easy to use clearing agent” is the sharpest contradiction between two documents in this entry. Treat the sheet as governing.

Sodium tungstate is mild and under-documented. Its MSDS calls it slightly hazardous by every route and then, several sections later, says it may affect genetic material and showed post-implantation mortality in animal studies. This course’s position is the conservative one: gloves, no dust, no splashes, and do not treat the 40 per cent bottle as innocuous because a pre-GHS MSDS could not decide.

The chromium question, answered by omission rather than by absence. Unlike the cyanotype kit from the same company, this box does contain a chromium(VI) compound, and the maker names it as a carcinogen on its own sheet. This course records the bottle, refuses the procedure, and notes for completeness that the same supplier’s superseded contrast route — the ammonium ferric oxalate solution #2 with potassium chlorate in it — is at Level D on a different ground. Both of the contrast agents this system has used in its history are ones the course declines. The one it accepts is the gold, which is in the box.

Storage

The five bottles as sold, at room temperature. The maker’s keeping claims, in its own words: the lithium palladium “will last almost indefinitely” and “does not oxidize or age”; the ferric ammonium oxalate “will last up to 2-3 years”; the sodium tungstate about five years; the gold “will last almost indefinitely”; the ammonium dichromate about five years, with the note that “It darkens in color over time”. Refrigeration is stated to be unnecessary for the palladium.

Dark, on the evidence of the substance sheet rather than the kit sheet. The instruction sheet never tells the buyer to keep the iron bottle in the dark. The company’s own sheet for the solid says “Protect from light. Sensitive to light. Store in light-resistant containers”, and the store listing for the solid carries the storage note “Light Sensitive”. A brown bottle in a cupboard costs nothing and is what this course recommends for the iron solution and for all the rest.

Glass for the palladium, never metal. This is the sheet’s own instruction and it is chemically sound: palladium(II) is reduced by most base metals, so a steel funnel, an aluminium measure or a metal cap liner will plate metallic palladium out of the solution and take it out of the process. The same rule extends to the development tray, where the sheet says it again.

Separate the dichromate physically. It is an oxidiser and its own sheet lists organic and combustible materials, powdered metals, reducing agents and acids among its incompatibles. In this box the reducing agent is the sodium bisulfite and the acid is whatever else is in the darkroom. Keep the dichromate bottle upright, in its own secondary container, away from the other four and away from the two powders, and label it for what it is.

The mixed coating solution has no published life, so give it none. Count what you will coat and coat what you count. With gold in the mixture there is a mechanism for the loss — gold(III) oxidising free oxalate — and no figure to keep it against.

The clearing bath is a session bath. “Throw away the clearing bath when finished.” Do not carry it over.

Label everything the moment it leaves the original bottle. Four of the five bottles say a name and a percentage; one says a name and nothing. A decant into an unlabelled jar produces a container nobody can identify, which is precisely the situation the unlabelled container procedure exists for. Write the substance name and, where there is one, the percentage, per labelling a container, and keep the bottles in the rotation the storage rotation procedure sets out.

Incompatibilities

Palladium and metal, which the sheet raises twice. “Always use glass containers, never metal as the palladium will plate out on the container”, and again at the development step, “Do not use metal trays for developing the print as this will adversely affect the print.” Glass, plastic and stoneware only, from the shot glass to the tray.

Palladium and the iron solution, before the moment of use. “Be very careful not to contaminate with ferric ammonium oxalate or any other chemicals.” Iron(II) reduces palladium(II); if the two meet in a bottle rather than on paper you get palladium black in the bottle. Dedicate a dropper to each solution and never return a used dropper to the wrong bottle — which is why the kit ships five of them for five bottles.

Dichromate and everything else in the box. Its own sheet names reducing agents, acids, organic and combustible materials and powdered metals. The sodium bisulfite in the same box is a reducing agent; a dichromate and a bisulfite are a redox pair. They must never meet, in a tray, a funnel, a waste container or a trap.

Bisulfite and acid. Sulfur dioxide, per the sheet. An acid stop bath from another process in the same sink is the realistic way this happens; see the acid spill procedure for what to do when it does.

Gold and free oxalate, over time rather than on contact. Ware’s reaction: gold(III) oxidises the free oxalate that dissociates from the iron complex, precipitating gold metal and evolving carbon dioxide. It is slow enough that a coating made and used at once is unaffected, and fast enough that a mixture left standing, or made in a warm room, is not what it was.

Gold and cesium palladium, which the sheet forbids in one line — “Gold Chloride cannot be used with Cesium Palladium” — and does not explain. Ware’s account of caesium salts of the tetrachlorometallates having low solubility is the plausible reading and this page does not assert it, because the maker gives no reason and no independent source addresses this specific pairing.

Ferric ammonium oxalate and oxidising agents and strong acids, on its own substance sheet. The oxidising agent in this box is the dichromate; the acid is the bisulfite in solution.

Alkaline-buffered paper. The sheet asks for 100 per cent rag with a hard surface and does not say unbuffered. It should: an alkaline reserve of chalk promotes the hydrolysis of the ferrioxalate anion, which is the route to a yellow iron stain that will not clear. The same warning is on the platinum clearing sequence and it applies unchanged here.

Brushes and rods, shared at your peril. A brush that has coated a silver process will fog this one; a brush that has coated this one carries palladium into whatever it touches next. See cross-contamination between alt processes.

Hard water. The sheet raises it twice — distilled water for the clearing bath where possible, and “sometimes hard water can cause problems” for the washes. Calcium is the reason: calcium oxalate is insoluble, and its formation in the sheet drives the ferrioxalate anion apart and leaves iron stains behind.

Waste

The first water bath carries most of it. Two minutes of running water takes away the unreduced palladium and the unreacted iron oxalate from every part of the sheet that did not print. Palladium is a noble metal and is worth recovering at any scale above the hobby; at hobby scale the standing arrangement applies. Read the disposal page and general chemical waste, and establish first what the local authority accepts.

The clearing bath is iron and chelate and should not be assumed harmless because EDTA is familiar. It carries the iron off the prints as a soluble complex, which is exactly what makes it mobile in the environment. Its sheet classifies the powder Acute toxicity Oral Category 4 and Inhalation Category 3. The bath is thrown away at the end of each session on the maker’s own instruction, so this is a routine volume rather than an occasional one.

Anything containing the dichromate is chromium(VI) waste and is not a drain matter. This is the sharp one. A drop of the 1 per cent solution carries about 0.17 mg of chromium on this course’s arithmetic, and chromium(VI) is a Group 1 human carcinogen whose freshwater fish LC50 the supplier’s own sheet gives as 136 mg/L. If the bottle is used, or if it is discarded unused, it goes to hazardous waste through the local authority’s route and never down a sink — and so does any tray, blotter, wash water or offcut that has carried it. See the chromium policy and general chemical waste. The course’s own answer is simpler: the bottle is never opened, and it is surrendered whole and labelled.

Sensitised offcuts and test strips. Dry them, keep them out of the compost, and put them in general waste rather than recycling; they carry iron, palladium and possibly gold.

Spent concentrates, if a bottle has to go. Keep the five separate. Do not combine them for convenience: the palladium and the iron mixed in a container are a sensitiser that will throw palladium black, and the dichromate mixed with the bisulfite is a redox reaction in a bottle.

Gold is worth keeping. A depleted first-wash tray from a session using gold contains recoverable metal, and at workshop volumes this is worth pooling rather than pouring.

Troubleshooting

The print is warm brown when a neutral black was wanted. Almost always the sheet was too dry at exposure. Raise the room humidity, shorten the drying, or use the two-step humidification; the mechanism is particle size and it is under The mechanism above. Check the room’s relative humidity against the sheet’s own floor of 50 per cent before changing anything chemical.

The print is weak and thin all over. Under-exposure, or too little coating solution — the sheet’s own diagnosis, “Too little in one area and the emulsion will be too thin and overexpose too quickly.” Print by inspection: the highlights are the end point, and they will look yellow in the frame. See a thin coat.

The emulsion came off in the wash. Too much coating solution, on the sheet’s own account. Use the drop table for the size, and stop brushing when the puddle and the bubbles are gone; see uneven coating thickness.

Blurred or soft areas, or spots where the image simply is not there. The sheet names this before you meet it: the wet sheet moves inside the acetate sandwich while it prints. Add backing paper to force contact, dry the surface a little further, and see uneven contact print.

Yellow stain in the highlights that survives the wash. Incomplete clearing, which the sheet also names: “If the print shows any yellowing in the highlights, it is not being properly cleared. Increase the concentration of the clearing agent or increase the time in the bath.” Check the water hardness too. See iron-silver highlights that will not clear and platinum stain from incomplete clearing.

The print yellowed months later. Residual iron(III) that the clearing did not reach, slowly hydrolysing. It also warms the image colour as it goes. The remedy is prevention: a fresh clearing bath, and not more than the twenty to twenty-five 8x10 prints the maker allows it. See an iron-silver print that faded.

Streaks and brush marks. Over-brushing, on the sheet’s own diagnosis. A drop of Tween 20 helps on every recommended paper except Arches Platine. See blotchy and streaked hand coating, and if the solution beaded rather than wetted, repellency spots.

Bubbles and pinholes in the coating. Pour and spread rather than dribble, and break any bubbles while the coating is still wet; see coating bubbles and pinholes. The sheet’s own instruction to pour water fast enough to break surface bubbles in the first bath is the same problem at the other end of the process.

Mottle that appears only in some weather. This process is more humidity-sensitive than any other in the formulary and the coating stage is where it shows. See mottled coating from humidity, and record the room’s relative humidity with every sheet.

Grain, and a tonal scale that stops short at the top. If the dichromate is in the mixture, that is what it does — the maker says so and Ware says so independently. This course’s answer is to take the dichromate out and lengthen the negative instead.

A palladium solution that has gone cloudy or thrown a dark deposit. Contamination, most likely with the iron solution or with a metal implement. See a sensitiser gone cloudy; the bottle is not recoverable.

Two sessions from the same kit do not match. Ask about humidity first and about the age of the mixed solution second. Then note that the third variable — the strength of the two bottles — is one that nobody outside the company can check, which is the argument of this whole page.

The clearing bath stopped working sooner than expected. Hard water, on the sheet’s own account, or more than twenty-five 8x10 prints through it. Mix it with distilled water and discard it at the end of the session.

Experiments

Measure the palladium. This is the experiment this page most wants somebody to do, because it would supply the number on which everything else here depends. Evaporate a known volume of the lithium palladium solution to dryness and weigh the residue, or better, reduce a known volume with an excess of a mild reducing agent, filter, dry and weigh the palladium metal. Either gives a strength for the bottle, and with it the molarity, the iron-to-palladium ratio implied by the drop chart, and the metal loading per square inch. A single well-recorded result would be the first independent statement of this product’s composition anywhere, and would make the maker’s own colour chart teachable.

Calibrate the drop. Count drops from each supplied dropper into a tared weighing boat until you have a gram, ten times over — see weighing a solid for the technique and balance and thermometer check for the instrument. One number converts the entire drop table into millilitres, lets the kit’s coverage be calculated, and tests the 0.04 ml a drop that this page borrowed from the company’s other bottle.

Put the kit against the open formula, one variable apart. Mix Ware’s sensitiser at his published 60 and 19 per cent, coat two strips of the same paper from the same batch beside two coated from the kit, humidify them together in one enclosure, expose them together and read all four on a densitometer. Ware’s argument predicts that the ammonium sensitiser prints out at a lower humidity than the lithium one does, and nobody has published the measurement. This is a checkable disagreement between two named authorities and it has been sitting unchecked since 1997.

Map the humidity. Coat six identical sheets, hold each over a different saturated salt solution — potassium carbonate at 44 per cent, calcium nitrate at 55, common salt at 76, ammonium chloride at 80 — for half an hour, expose them together and photograph the set beside a grey scale. That is Ware’s humidity series repeated for this kit’s chemistry, and it turns the sheet’s crackle test into a number.

Find out what the sodium tungstate does. The open question at the end of The mechanism. Three matched sheets — no tungstate, two drops, three drops — coated, humidified identically, exposed together and read for both density and colour; then the same three at two different humidities, to separate a humectant effect from an adsorbate one. If the tungstate’s warming survives at constant humidity it is not a humectant, and that single result would be the first published word on the mechanism of the best-quantified additive in the box.

Time the mixed solution, with and without gold. Mix twenty drops of each, coat a strip at once, then at fifteen minutes, one hour and four hours, keeping the glass in the dark; repeat with four drops of the gold substituted for four of the palladium. Ware’s gold-and-oxalate reaction predicts that only the gold-bearing series degrades. The maker publishes no keeping time at all for the mixture and this would supply one.

Test the two-to-three-stop claim. Coat one sheet from this kit and one from the three-solution drop system, expose both under the same source through the same step tablet, process each by its own route and compare the exposures at a matched density. The maker’s speed claim is specific and checkable in an afternoon.

Read the colour chart back. Print all eight of the rows that can be made from the box, on one paper, at one humidity, from one session, and photograph them together with a colour reference. The chart gives colours in words; nobody has published it in pictures, and the eleventh row — the one with seventeen drops of metal against twelve of iron — would either turn out to work or turn out to be a typographical error, and either answer is worth having.

Record all of it. A bought product earns a line in the formula version record as much as a mixed one does: the purchase date, the date each bottle was opened, the room’s relative humidity and temperature at coating, the drying method and its duration, the drop count of every solution used, the water, and what the first sheet did. On a product whose two principal solutions carry no strength at all, your own record of the bottles is the only specification that will ever exist.