HARMAN SELENIUM TONER

This is a product page, not a formula page. Every other toner in this library arrives as a list of quantities with a source beside it and an account of what each one is doing — six grams of selenium powder, two hundred and fifty of sodium sulphide, ten millilitres of a one per cent gold stock. Nobody outside Harman knows the quantities in this bottle. What follows is what its maker publishes, which for a toner sold on a two-page sheet is more procedure than chemistry; what its maker’s safety data sheet discloses, which is three substances and turns out to be the most informative selenium document in this corpus; what the two together still leave unknown; and the open formula the course does teach — which, uniquely in this library, is one it asks nobody to make.

HARMAN technology Limited (ILFORD Photo) — sold as liquid concentrate

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
Ammonium thiosulfatenamed on the sheet as Ammonium ThiosulphateCAS 7783-18-8The maker states no function; a thiosulfate is a silver-halide solvent and a silver complexant, which is the course's reading of what it is doing and not HARMAN's statement	10-30%
Sodium sulfite (anhydrous)named on the sheet as Sodium SulphiteCAS 7757-83-7The maker states no function, and this page does not choose between the two the chemistry allows	10-30%
Sodium seleniteCAS 10102-18-8The selenium, named by CAS number — the only line on the sheet that carries a hazard classification, and the source of the whole of the product's own	1-5%	H300, H315, H317, H319, H330, H400, H410

Not disclosed. HARMAN publishes no composition for HARMAN SELENIUM TONER. The technical sheet's only compositional statement is the word *selenium* in the product's own name. The safety data sheet names three components — ammonium thiosulphate, sodium sulphite and sodium selenite — and gives each the concentration band it needs in order to classify a hazard, which is not an assay: section 11 records that every classification on the sheet was reached by calculation from those bands. Two of the three bands are a factor of three wide, and between about a third and two thirds of the bottle is accounted for by nothing on the sheet at all. Neither document gives a pH for the concentrate or for either working dilution, a specific gravity, a density, a colour, an odour, a selenium content as the element, a function for any of the three components, a toning time at the 1+3 dilution, a capacity at the 1+20 dilution, or any figure for how much of the silver image a given time and dilution actually converts. Section 9 of the safety data sheet records every physical property of the liquid except that it is a liquid as *Not known*. A reader who wants to know how much selenium is in the tray, or to change that number and watch the tone move with it, cannot get there from HARMAN's literature — and the open formula that would answer it is one this course publishes at Level D and asks nobody to make.

Nearest open formula. Kodak T-55 — Both are direct selenium toners for paper, sold or made as a stock and diluted for a tray at room temperature, and both end with a print that is part silver selenide. Everything else about the comparison is unusual, because this is the one entry in the formulary where the open formula is the thing you should *not* make. Kodak Limited's T-55 publishes its quantities — 6 g of selenium powder, 300 g of crystalline sulfite, 190 g of ammonium chloride to the litre — and reaches them by boiling elemental selenium in an open pan until it dissolves, which is why the course carries it at Level D and gives no procedure for it. HARMAN publishes no quantities at all and reaches the same image by starting from a selenium salt that is already soluble, in a bottle you dilute with a measuring cylinder. So the trade here is not the formulary's usual one of a known composition against a known performance: it is a known composition you must not prepare against an unknown composition you safely can. The two also differ in what the selenium is. T-55 dissolves the element in a sulfite, which the wider literature reads as a selenosulfate; HARMAN's sheet names sodium selenite, selenium(IV), by CAS number. That is the first time in this corpus a manufacturer has named its species, and it does not make the two baths the same chemistry.

Purpose

To convert part of a finished silver print to silver selenide, for either of two reasons that HARMAN separates by dilution and never confuses.

At 1+3, to change the colour. The sheet’s own range is “cool chocolate-brown, through purplish brown, to little discernable change”, and it says outright that the result depends on the paper rather than on the toner: warm tone papers usually produce the most visible effects.

At 1+20, to protect the print and leave it looking untouched. HARMAN’s words are “where the primary reason is for protection of the image, with minimal tone change”, and it is the only dilution on the sheet with a time against it — complete in two to four minutes.

That second purpose is why this bottle appears in ILFORD’s literature far more often than the toner sheet alone would suggest. The technical sheets for MULTIGRADE FB CLASSIC, FB COOLTONE and ILFOBROM GALERIE FB all recommend that prints made for display be toned against the oxidising gases found in many environments, and all three recommend selenium because it has little effect on the image colour of those papers. HARMAN’s own Direct Positive Paper sheet goes further and names this product: tone with HARMAN SELENIUM TONER, “which has little effect on the colour of an image, but does help to protect it”.

So the sales argument is unusual. Most toners are bought for what they do to a print’s appearance. This one is bought, in ILFORD’s own recommended sequences, for what it does to a print that will not look any different afterwards. The selenium toned silver gelatin print entry sets out the process; this page is about the bottle.

Recommended uses

Dish or tray toning of black and white paper, resin coated or fibre based. That is the whole of the application the sheet names — “TONER FOR THE DISH/TRAY TONING OF BLACK AND WHITE PHOTOGRAPHIC PAPER” is its subtitle — and no other material, no other vessel and no machine process appears anywhere on it.

Display prints and prints wanted for the long term, at 1+20. This is ILFORD’s own recommendation across its fibre range and its resin-coated range alike, with one honest qualification on the RC sheet that the FB sheets do not carry: on resin-coated papers “there may be some change in image colour depending on the dilution and amount of toning applied”.

Inside the optimum permanence sequence, diluted with working strength ILFORD WASHAID instead of water. Four ILFORD paper sheets print the same table: fix for one minute in RAPID FIXER or HYPAM at 1+4, tone, ten minutes in WASHAID at 1+4 with intermittent agitation, thirty minutes in fresh running water. The toning step is the only one in that table without a number.

Warm-tone papers, if visible colour is what you are after. HARMAN says so directly, and Kodak’s independent account of the family agrees: warm-tone papers move most, neutral papers go purplish brown, cold-tone papers barely move at all.

With a reference print, the first several times. The sheet’s suggestion is worth more than most manufacturers’ advice: make two identical prints, leave one in the holding dish of water, and compare. A toning change is a slow change in a wet print under a safelight, which is close to the worst possible viewing condition for judging a hue.

Not for anything the sheet does not name. No film, no plates, no machine processing, no use as a fixer despite what is in it, and no dilution between 1+3 and 1+20 with a published behaviour attached.

When another formula is preferable

• Where warm brown is wanted on a neutral paper, a sulfide route — Kodak Limited’s T-52 or Kodak’s T-7a — which changes the colour of anything, where selenium changes some papers and not others.
• Where a redder result is wanted than selenium alone gives, Kodak Limited’s T-56, which puts selenium into a sulfide bath after a bleach. It is also Level D and for the same reason.
• Where no selenium is acceptable at all, the hypo-alum bath T-1a, which is the only sepia route in this formulary at Level B and reaches a silver sulfide image without a sulfide reagent ever being handled.
• Where protection is wanted and colour must not move at all, GP-1, Kodak’s gold protective solution: ten millilitres of a one per cent gold stock, a thiocyanate and a litre of water, published with its quantities and its ten minutes at 20 °C. It is the open formula for the archival job, and it costs what gold costs.
• Where the print is not permanent enough and toning is being asked to fix it, nothing on this page will help. Residual thiosulfate and residual silver are a washing and fixing problem, and the answer is WASHAID, the open sulfite washing aid or Kodak’s hypo clearing agent followed by a full wash, with the residual hypo and silver tests to prove it. A toner containing thiosulfate is not a rescue for an under-washed print; it is more thiosulfate.
• When you want to understand a selenium bath rather than buy one, the answer this formulary usually gives — mix the open formula — is the one answer this page will not give. Kodak Limited’s T-55 publishes every quantity and is carried at Level D, because its second step is boiling elemental selenium powder in an open pan of sulfite solution until it dissolves. Read it for the chemistry. Do not make it.

What the maker publishes

Two pages, dated June 2010, and almost all of it is procedure. There is no pH, no specific gravity, no table of materials, no composition and no chemistry. What there is, is unusually specific about how to stand at a tray.

Two dilutions with two different jobs. 1+3 for normal toning applications; 1+20 where the primary reason is protection of the image with minimal tone change. Stir process solutions thoroughly before use. Those two ratios are the only numbers on the sheet that describe the product rather than the session.

One published time, and it belongs to the archival dilution. At 1+20, protection of the image will be complete in two to four minutes. At 1+3 there is no time at all: you tone until it looks right, against a reference print, and the sheet says so as a method rather than as an omission.

A temperature with a tolerance, and it is a tight one. 20 °C/68 °F, ±1 °C/2 °F. ILFORD gives its stop bath a six-degree band and its developers a wider one than this; the toner gets two degrees.

Three dishes, and the outer two are warmer. The toner sits in the centre; a holding dish of plain water on either side, approximately 4 °C warmer than the toner. The print goes from the fixer into the first, from the first into the toner, and from the toner into the second. HARMAN gives no reason for the four degrees, and this page does not supply one.

How much to mix. Three litres of working solution is given as sufficient for a dish measuring 12 × 16 inches (30.5 × 40.6 cm) — a volume rather than a depth, which is the practical form of the instruction.

The toning method, in the sheet’s own order. Take the print by its top corners with both hands, lift it from the holding dish, slide it quickly into the toner, and agitate for the whole period of toning by gently rocking the dish. Do not continually observe the print in the toner, because that makes the subtle changes harder to see; compare it with the reference print instead.

How to stop it. Into the second holding dish, agitated for 30 to 40 seconds. If more toning is wanted, the print goes back. That is an unusually forgiving instruction and it is the practical consequence of a bath that works by degrees rather than by a threshold.

The wash. Resin-coated prints for a further two minutes; fibre prints for at least thirty minutes in fresh running water above 5 °C/41 °F; or, for fibre, the ILFORD optimum permanence wash sequence instead.

A capacity, and a frank statement of what that word means here. At 1+3, at least the equivalent of 25 sheets of 20.3 × 25.4 cm per litre. And then the sentence that matters more than the figure: the capacity “is in practical terms limited by the time it takes for the toning effect to be completed”, and “as the solution is used and/or ages, the rate of tonal change will become progressively slower”. This bath does not die; it slows down.

Three working-solution lives and two storage figures. Up to six months in full, tightly capped bottles; one month in half, tightly capped bottles; up to seven days in an open tray. Full unopened bottles of concentrate stored at 5 to 20 °C keep for two years; once opened, use completely within six months.

A health and safety paragraph on the technical sheet itself, which is not something ILFORD prints for its developers. Toxic if swallowed. May cause sensitisation by skin contact. Keep away from food, drink and animal feeding stuffs. Avoid contact with skin. Wear suitable gloves and eye/face protection. Keep locked up and out of reach of children. Do not empty into drains; dispose of this material and its container at a hazardous or special waste collection point. And separately, under Additional Safety Information: it is a toxic chemical, work in a well-ventilated area preferably with some form of air extraction, and wear rubber gloves in all use and disposal.

And a 2024 safety data sheet, which is where the rest of this page comes from. Issue date 18 July 2024, revision 1, product code 1143207, identified use “toning solution for monochrome prints”, uses advised against “not known”.

⁇The maker's two documents disagree about how toxic it is

The technical sheet (June 2010) opens its health and safety paragraph with “Toxic if swallowed” and calls the product “a toxic chemical”.

The safety data sheet (18 July 2024) classifies the mixture Acute Tox. 4 and prints H302, harmful if swallowed, with signal word Warning and pictogram GHS07 alone. Under GHS those are different categories with different words, and toxic is the stronger of the two.

Three readings are available and the course adopts none of them: the 2010 wording predates the current classification and was written under the old European risk phrases; the mixture may have been reformulated in the fourteen years between the documents; or the 2010 sheet may simply have been conservative. HARMAN says nothing about which, and no document in this corpus resolves it.

What this page does is state the position rather than pick one. The 2024 safety data sheet is the current classification and is what the Safety section below is built from. The 2010 wording is recorded here because it is still on the sheet in the box, because it is stricter rather than laxer, and because a reader who follows it is not being made less safe. Both documents agree on every control that matters: gloves, eye protection, ventilation, locked storage, away from food, and nothing down the drain.

What is not disclosed

The composition, entirely. The word selenium appears on the technical sheet only in the product’s name. There is no ingredient list, no active-ingredient statement of the kind Kodak prints for its Rapid Selenium Toner, and no concentration of anything.

How much selenium is in it, in any form. Kodak at least says of its own product that the active ingredient is a sulfite salt at less than two per cent and that working solutions generally contain less than half a per cent of what it calls “selenium sulfite”. HARMAN publishes no equivalent figure, and the safety data sheet’s 1-5 % band for sodium selenite is a hazard band, not a selenium content.

Any pH at all — and on a selenium page that is the omission with teeth. The whole handling rule for this chemistry is no acid, ever, because selenium salts and acid give hydrogen selenide, whose workplace limit is 0.02 ppm. A reader who wants to know how much margin the bath has before an accidental carry-over of stop bath matters cannot find out from either document. Section 9 of the safety data sheet records pH as Not known.

Every other physical property. Section 9 gives appearance as “Liquid” and then records colour, odour, odour threshold, pH, melting point, boiling point, flash point, density, relative density, water solubility, partition coefficient, viscosity, decomposition temperature, explosive properties and oxidising properties all as Not known.

What any of the three components is doing. The sheet names them, bands them, classifies one of them and offers no function for any.

A toning time at 1+3. The sheet gives the printer a method for judging it and no number to start from — not a range, not a typical figure, not a worked example.

A capacity at 1+20. The single capacity figure is attached to 1+3. The dilution ILFORD’s own paper sheets build into their archival sequence has no published capacity, which means the reader using this product for permanence has no maker’s figure for when the bath stops delivering it.

What “protection” amounts to. HARMAN says the toner “enhances the archival stability, and maximum density of prints” and stops. There is no figure for either, no conversion fraction, no accelerated-ageing result and no reference to one. That the conversion is partial at all comes from Moersch rather than from HARMAN, and the course’s inability to put a number on the mechanism is set out on the silver selenide page.

Which dilution the WASHAID sequence intends. Four ILFORD paper sheets say to dilute the toner with working strength WASHAID instead of water. None of them says whether that is at 1+3, at 1+20 or at something else, and the toner’s own sheet does not mention WASHAID.

!Why the three bands cannot be added up

There are three numbers in the composition table and the temptation to treat them as a recipe is correspondingly strong. Do the arithmetic once and it goes away.

Ammonium thiosulphate is banded at 10-30 %, sodium sulphite at 10-30 %, sodium selenite at 1-5 %. Taken at their lower limits the three named substances account for 21 per cent of the bottle; taken at their upper limits, 65 per cent. So somewhere between 35 and 79 per cent of what is in the bottle is named by nothing on the sheet — most of it water, on any sensible reading. Both totals are the course’s arithmetic on HARMAN’s own printed figures, and neither is a composition.

Worse for anyone tempted: two of the three bands are a factor of three wide. A working bath made at 1+3 from a concentrate holding 10 per cent thiosulfate contains a third of the thiosulfate of one made from a concentrate holding 30 per cent, and those two baths would fix at measurably different rates. The band is not a manufacturing tolerance. It is a band wide enough that the mixture’s classification can be calculated conservatively from it, and section 11 confirms that calculation is exactly what happened: every classification on the sheet is recorded as reached by calculation method, with a calculated acute toxicity estimate of 324.99 by ingestion and 32.5 by inhalation.

Read as what it is — a hazard classification — this table is evidence. Read as a recipe it becomes an invention with a citation stapled to it, and the invention in this particular case would be a selenium toning formula, which is close to the last thing this course should put into circulation.

Disclosed components

Three, in the order the safety data sheet prints them, each with the band the sheet states and not a quantity. This is a longer table than most product pages in this library carry, and the third line on it is the most valuable single sentence any manufacturer has contributed to this course’s account of selenium toning.

Ammonium thiosulphate, CAS 7783-18-8, EC 231-982-0, 10-30 %, not classified. The largest declared component of the bottle, jointly with the sulfite, and the one that makes a selenium toner something other than a bath of selenium. It carries no hazard classification at all on the sheet and no pictogram, which is why a reader skimming the table can miss that it is there in fixer quantities. What it is doing, HARMAN does not say. What can be said without inventing anything is that ammonium thiosulphate is the working agent of every rapid fixer in this formulary, including ILFORD’s own RAPID FIXER and HYPAM: it is a silver-halide solvent and a strong complexant for silver. That a selenium toner is therefore also a weak fixing bath is the course’s reading, marked as an inference under Rule 7 — but it is a reading with independent support, because Moersch’s safety data sheet for its own selenium toner declares 20 per cent w/w ammonium thiosulfate, and the course’s process entry already records the consequence. The practical form of it is a warning rather than a feature: a print that goes into this bath under-fixed or under-washed is not being rescued by the thiosulfate in it. HARMAN’s own first instruction is that the print “should be developed and fixed properly” before toning, and Kodak is blunter still — residual silver salts and traces of hypo cause stains, uneven tones and fading.

Sodium sulphite, CAS 7757-83-7, EC 231-821-4, 10-30 %, not classified. The other large declared component, and the one whose presence would be predicted from the history even if the sheet had not printed it. Every historical selenium toner in this course solves the same problem the same way: the element will not dissolve in water, and a sulfite solution is what takes it up. Kodak Limited’s T-55 boils six grams of selenium powder into a sulfite stock for exactly that reason, and the sodium selenosulfate page records what the wider chemical literature calls the product. But that cannot be what the sulfite is for here, because HARMAN’s selenium arrives already soluble as a selenite: nothing needs dissolving. Two readings are available and the course adopts neither — sulfite is the standard antioxidant of photographic solutions and would protect a thiosulfate-bearing bath from oxidation, and sulfite is also the medium in which selenium species are known to interconvert. HARMAN states no function, no other document in the corpus discusses this product’s sulfite, and a page that picked one of the two would be reconstructing a formulation by inference. It is named, it is banded, and that is the end of what is known.

Sodium selenite, CAS 10102-18-8, EC 233-267-9, 1-5 %. The selenium. This is the only line in the composition table that carries a classification — Acute Tox. 2 with H300, fatal if swallowed; Skin Irrit. 2, H315; Skin Sens. 1, H317; Eye Irrit. 2, H319; Acute Tox. 2 with H330, fatal if inhaled; Aquatic Acute 1, H400; and Aquatic Chronic 1, H410, with pictograms GHS06, GHS07 and GHS09 — and the whole of the product’s own milder classification is calculated down from it. It is also the only substance HARMAN names in section 15.1 under the UK REACH Annex XVII restrictions list, where every other regulatory line on the sheet reads Not listed. Read its encyclopaedia page before this one for the hazard, the exposure limits and the reason the solid is a Level C substance while the bought bottle is not.

⁇Four sheets, four selenium species — and this is the first one with a CAS number

The course’s sodium selenite and selenium toned print pages both record a disagreement between three manufacturers’ statements:

• Kodak, on Rapid Selenium Toner: the active ingredient is “a sulfite salt” at less than two per cent, with working solutions containing less than half a per cent of “selenium sulfite” — a description rather than a name, with no CAS number behind it.
• Moersch, on MT1 Selentoner: 2 to 3 per cent w/w sodium selenate, CAS 13410-01-0 — selenium(VI).
• Wall’s 1924 handbook, for the historical baths: sodium selenide, selenium(−II), made by dissolving the element in sodium sulfide or fusing it with caustic soda.

HARMAN’s sheet is the fourth, and it names sodium selenite, CAS 10102-18-8 — selenium(IV). That is a fourth species and a third distinct oxidation state among the modern products, so it does not resolve the disagreement; it widens it, and it settles nothing about what is in anybody else’s bottle.

What it does settle is smaller and worth having. Until this sheet, no manufacturer in this corpus had named the selenium compound in a photographic toner with a registry number, and the sodium selenite page could record that PubChem’s own use listings for the substance name glass, ceramics, bacteriology, seed testing, porcelain, soil and feed supplementation and medicine — and not photography. One manufacturer now names it for photography, on its own hazard sheet, under its own product code. That also tells you something about the other sheets: Kodak’s vagueness is a choice about what to disclose, not a limit of the document type, because HARMAN’s identically-regulated sheet is specific.

Everything in this box is what four documents say. None of it is a statement about what is in a bottle other than the one its own sheet describes, and the reading that the three modern toners share a common architecture is set out — and marked as an inference — under The mechanism below.

And what is in the bottle and not in the table. Water, which no safety data sheet declares because it drives no classification, and which on the arithmetic above is most of what is left. And whatever else there may be below the declaration threshold: a wetting agent, a sequestrant, a buffer, a preservative. The sheet’s silence on those is not evidence that there are none. A composition table lists the substances that drive the classification, not the contents, and on a page about a product whose composition is secret that distinction is the whole point.

Behaviour

Dilution is the control, and the two published dilutions are two different products. At 1+3 the bath changes colour and the printer judges when to stop. At 1+20 the bath is meant to leave the print looking the same and takes two to four minutes to do it. Nothing in HARMAN’s literature covers the range between.

The higher densities go first. That is Moersch’s observation, recorded on the sodium selenite page, and it is the single most useful thing to know about any selenium bath: a strong bath used briefly intensifies the shadows and leaves the highlights alone, while a very dilute bath used longer will reach the highlights but risks losing shadow density first. HARMAN’s two dilutions sit at opposite ends of exactly that trade.

The conversion is partial, always. Moersch records that after six minutes not all the silver has been transformed. A selenium-toned print is normally a mixture of silver selenide and untoned silver, in proportions the printer chose by time and dilution without necessarily knowing it — which means protection is proportional to a conversion nobody measures.

Toning continues after the print leaves the tray. HARMAN’s stop is 30 to 40 seconds of agitation in the second water dish, and Kodak’s independent account says of its own product that toning continues to some extent in the wash. The practical consequence is the same on both sheets: pull the print slightly before it looks right.

It is reversible in the useful direction only. A print that has not toned enough goes back in; HARMAN says so explicitly. A print that has toned too far does not come back.

Exhaustion is a slope, not a cliff, and the maker says so in as many words. “The capacity of the working strength solution is in practical terms limited by the time it takes for the toning effect to be completed. As the solution is used and/or ages, the rate of tonal change will become progressively slower.” That is a different failure model from a fixer’s or a stop bath’s, and it has two consequences. First, the 25-sheets-per-litre figure is a floor — HARMAN says “at least” — and not a threshold. Second, a bath that is getting slower is indistinguishable from a printer who is becoming more patient, which is why timing the toning of a standard test print is the only honest way to track it.

It keeps unusually well. Six months at working strength in a full, tightly capped bottle, a month half full, a week in an open tray. Set that against ILFOSTOP’s seven working days at working strength and it is clear that the seven-day figure here belongs to the open tray and evaporation, not to the chemistry.

The temperature band is tight and nobody explains why. ±1 °C on a bath whose published time at one dilution is “two to four minutes” and at the other is nothing at all. HARMAN offers no reason, and this page does not invent one.

Image characteristics

Three outcomes on three classes of paper, and one of them is “nothing”. HARMAN’s own range runs from cool chocolate-brown, through purplish brown, to little discernible change, with warm tone papers usually producing the most visible effects. Kodak’s independent account of the family gives the same three answers in the same order.

On ILFORD’s own neutral and cold papers, invisibility is the design intent. The FB CLASSIC, FB COOLTONE and ILFOBROM GALERIE FB sheets all recommend selenium because it has little effect on those papers’ image colour. On MULTIGRADE RC papers the recommendation is qualified — “there may be some change in image colour depending on the dilution and amount of toning applied” — which is the one place ILFORD admits the archival dilution can be seen.

Maximum density rises, and the claim has no number attached. HARMAN states that the toner “enhances the archival stability, and maximum density of prints”. Kodak’s toning publication carries a curve showing increased upper-scale contrast and D-max, at a different dilution, for a different product, on a paper that no longer exists. The direction is well attested across both makers; the magnitude for any current ILFORD paper is not published by anybody.

The signature survives. The Getty Conservation Institute’s atlas records that selenium treatment can be detected by X-ray fluorescence long afterwards, which is the opposite of sulfur toning, whose signal hides inside the baryta layer. A print toned at 1+20 to look untoned is nonetheless identifiable as toned in a century.

Which is the honest summary of this product’s central case. At the protective dilution you are buying a change you have agreed in advance not to be able to see, on the strength of a maker’s sentence and a conservator’s atlas. That is a reasonable thing to buy. It is not the same kind of claim as “this developer gives finer grain”, and it should not be assessed as though it were.

The mechanism

The end state is not in doubt and is not this page’s inference. Kodak states outright that a selenium toner converts the silver image to silver selenide. What the course cannot do is put a number behind the protection: no source it holds gives a solubility product, a solubility figure or a formation constant for Ag₂Se, so the mechanism is recorded as an observed increase in chemical and environmental stability rather than as a calculation, and no balanced equation for the toning step is printed here, because the course does not hold one and writing a plausible one would be the failure Rule 1 exists to prevent.

What this sheet adds to the mechanism is an identity, and that is genuinely new. Until now the course could say that a selenium toner starts from some soluble selenium compound and could not say which, because the three manufacturers who described theirs described three different things. HARMAN names sodium selenite, selenium(IV), with a CAS number. That is a fact about this product from its maker’s own hazard sheet. It is not a fact about Kodak’s product, or Moersch’s, or T-55’s stock, and it does not license reading selenite back into any of them.

⚗Three functional slots, two makers, and an inference marked as one

Set HARMAN’s composition table beside Moersch’s and the parallel is hard to miss:

	HARMAN Selenium Toner	Moersch MT1 Selentoner
Thiosulfate	Ammonium thiosulphate, 10-30 %	Ammonium thiosulfate, 20 % w/w
Sulfite	Sodium sulphite, 10-30 %	Ammonium sulfite, 10 % w/w
Selenium salt	Sodium selenite (Se IV), 1-5 %	Sodium selenate (Se VI), 2-3 % w/w

Two independent European manufacturers, two safety data sheets written to the same regulation, and three components each that fall into the same three slots — a thiosulfate, a sulfite and a selenium salt — with a different salt in two of the three.

That a modern packaged selenium toner is built from those three functional slots is the course’s reading of two composition tables, and it is an inference under Rule 7, not a statement by either maker. Neither sheet assigns a function to anything. Two sheets are not a family, the bands on one and the point values on the other are not comparable measurements, and Kodak’s product — which names no compound at all — may or may not fit the pattern.

What the comparison does establish, without inference, is that the two makers disagree about the oxidation state of their selenium. Selenite is selenium(IV); selenate is selenium(VI). Those are different compounds with different chemistry, sold for the same job, and any account of selenium toning that speaks of “the selenium toner” as one substance is wrong about at least one of them.

Why the bath is also a weak fixer, and why that is a caution rather than a convenience. At 10-30 per cent, ammonium thiosulphate is present in the concentrate at a strength that would be recognisable in a fixer bottle. The reading that the working bath therefore has some silver-halide solvent action is the course’s, marked as an inference, and it is supported by Moersch’s declared 20 per cent rather than derived from HARMAN. What follows from it is practical: the toner is not a place to finish an inadequate fix, the print must be properly fixed and washed before it goes in, and the bath’s own waste stream carries thiosulfate as well as selenium and silver.

Why the whole of the handling is about acid, on a sheet that never mentions pH. The sodium selenite page carries the reasoning with its sources: both CAMEO and the international safety card record that selenite reacts with strong acids to generate a toxic hazard, neither names the gas, and HSE’s EH40 sets dihydrogen selenide at 0.02 ppm over eight hours — among the lowest limits in the whole table and more than two hundred times lower than hydrogen sulfide’s. The course states plainly that it has not verified which species an acidified selenite bath releases. It has verified that the family’s volatile hydride is controlled at a level a darkroom has no way of measuring, which is why the rule is absolute rather than proportionate.

What HARMAN’s four degrees are for. The two holding dishes are approximately 4 °C warmer than the toner. HARMAN gives no reason, no other document in the corpus repeats the instruction, and this page records it as an instruction rather than explaining it.

The nearest open formula

Kodak T-55, Kodak Limited’s direct selenium toner of 1949 — and this is the one comparison in the formulary that does not end where the others do.

Everywhere else in this library, a product page’s argument is: here is a bottle with a documented performance and an unknowable composition, here is an open formula with a known composition and an undocumented performance, and here is the bench where you turn one into the other. That argument depends on the open formula being something a reader can make. T-55 is not. Its second step is boiling six grams of elemental selenium powder in an open pan of hot sulfite solution until it dissolves, and the course carries it at Level D for exactly that reason.

	Kodak T-55 (1949)	HARMAN SELENIUM TONER
Composition	Published in full: 300 g crystalline sodium sulphite, 6 g selenium powder, 190 g ammonium chloride, water to 1000 c.c.	Not published; three components banded on a hazard sheet
Selenium species	The element, dissolved by boiling in sulfite; the wider literature reads the product as a selenosulfate and the course has not verified that	Sodium selenite, CAS 10102-18-8, named by the maker at 1-5 %
How the selenium is got into solution	By the person making it, at the boil	Already in solution when the bottle is opened
Dilution	1 + 5, and no other	1+3 for tone, 1+20 for protection
Time and temperature	10 to 15 minutes at 18 °C	2 to 4 minutes at 20 °C at 1+20; no published time at 1+3
Capacity	Not published	At least 25 sheets of 8 × 10 per litre at 1+3; nothing at 1+20
Keeping	Not published	2 years sealed; 6 months once opened; 6 months, 1 month or 7 days at working strength
Ammonium chloride	190 g/L, function unexplained by Kodak Limited and by this course	Not present, or at least not declared
Safety level	D — historical study, no procedure given	B — a liquid concentrate poured into a dish
What you can change	Everything, in principle; nothing, in practice, because the course gives no procedure	The dilution, the time and the temperature
What the course recommends	Read it	Use it

The last row is the argument, and it inverts the usual one. Buying the bottle gets you a documented procedure, two purposeful dilutions, a capacity, three keeping figures and a hazard sheet, from a bath whose composition is secret. Mixing the open formula gets you every quantity — and a step this course will not ask anyone to perform. This is the entry where the honest conclusion is to buy the product, and the value of the open formula is that it explains what is happening rather than offering an alternative.

Two further things the comparison shows. First, the composition being published does not make the older bath better understood: Kodak Limited gives no function for its 190 g/L of ammonium chloride, and neither can this course, so T-55 has a published quantity whose purpose is as unknown as HARMAN’s sulfite. Second, the two baths are not the same chemistry — one starts from the element dissolved in sulfite, the other from a selenite salt — and a reader who treats T-55 as a reconstruction of the bottle has assumed exactly the thing this page refuses to assert.

Safety

Level B, and the reasoning belongs on the page rather than in a database.

HARMAN classifies the mixture Acute Tox. 4, Skin Sens. 1 and Aquatic Chronic 3: pictogram GHS07, signal word Warning, hazard statements H302, harmful if swallowed, H317, may cause an allergic skin reaction, and H412, harmful to aquatic life with long lasting effects. Section 2.3, other hazards, reads none known. The precautionary statements are P101, P280, P301+P310, P302+P352, P330, P405 store locked up and P501.

Why B and not A. The rubric’s Level A ceiling is substances whose classification is at most irritant, harmful if swallowed, or corrosive at the concentrations actually handled. A sensitiser is above that ceiling and is named explicitly in the first Level B criterion. This mixture is one, and the maker’s own 2010 sheet says so in plainer words than the hazard code does: “may cause sensitisation by skin contact”.

Why B and not C. The Level C criterion that would apply names reagents classified as acutely toxic or as sensitisers where a fume cupboard or specialist disposal is the recognised control. The mixture as sold is not classified acutely toxic in a category that calls for containment, the operation is pouring a liquid concentrate into a dish at room temperature with no weighing of a solid at any point, and HARMAN’s own control is a well-ventilated area, preferably with some form of air extraction, with a type A filter mask recorded as something that “may be appropriate” rather than as a requirement. The course’s process entry reaches the same conclusion for the same object.

⚠The bottle is Level B; the solid inside it is Level C

Sodium selenite is a Level C substance on its own page, classified Danger, fatal if swallowed and fatal or inhaled toxic by inhalation, with a workplace limit for selenium of a fifth of a milligram per cubic metre. Nothing on this page contradicts that, and the two classifications are not in tension: the level is assigned to an operation, not to a substance.

Weighing a hygroscopic powder classified H300 and H330 is a fume-cupboard operation and this course gives no procedure for it. Diluting a bottled liquid in which that powder is already present at 1-5 % is not. The person who buys this bottle has bought their way out of the Level C step, which is the same trade the whole product-page category exists to describe, and it is the strongest practical argument on this page for buying rather than mixing.

Personal protection, as the two documents specify it. Impervious gloves to EN 374, with the breakthrough time taken from the glove maker rather than assumed — glove selection is where that goes, and HARMAN’s technical sheet is blunter: rubber gloves in all use and disposal. Eye protection with side protection to EN ISO 16321-1; the technical sheet says eye/face protection and an apron. Protective clothing. Hands and exposed skin washed thoroughly after handling. Do not eat, drink or smoke when using the product.

Ventilation, and the one respiratory line ILFORD prints for no other product in this corpus. Section 8.2.1 asks for use with ventilation, local exhaust ventilation or breathing protection, and a washing facility or water for eye and skin cleaning. Section 8.2.2 records that a suitable mask with filter type A (EN14387 or EN405) may be appropriate — no other ILFORD safety data sheet read for this formulary names a filter type. The technical sheet’s own wording is a well-ventilated area, “preferably with some form of air extraction system”. Section 8.1.1 records that no occupational exposure limit is assigned to anything in the product, which is a statement about the mixture and not about selenium: the limits on the selenium and sodium selenite pages are milligram-per-cubic-metre figures for the element and its compounds, and a domestic room has no way of knowing whether it meets them.

Sensitisation is the hazard that changes with repetition, and it is managed differently from the others. H317 is not a dose that gets worse; it is a state that can be acquired. HSE’s approach to sensitisers, recorded on the sodium selenite page, is that once a person has reacted, further exposure must be prevented rather than managed. A rash appearing after several toning sessions is not a reason to be more careful next time.

First aid, in the sheet’s own words. Skin contact: take off immediately all contaminated clothing and wash it before reuse; if skin irritation or rash occurs, get medical advice. Ingestion: rinse the mouth and immediately call a poison centre or doctor. Inhalation and eye contact: treat symptomatically. Most important symptoms: allergic contact dermatitis. The first-aid page has the course’s fuller procedure and the eyewash SOP has the technique.

In a fire, section 5.2 states the product may decompose giving off toxic and irritant vapours, and section 5.3 asks firefighters for complete protective clothing including self-contained breathing apparatus and for fire control water to be diked for later disposal — which is not a line ILFORD prints for its developers.

⚠The bath removes its own warning, twice over

Wall’s closing sentence on the selenium family, quoted on the selenium page, is the one to remember: all selenium salts have an intense garlic odour, which is very lasting. NIOSH’s list of symptoms of selenium exposure includes garlic breath. The smell of the bath and the sign of having absorbed it are the same smell, and a person cannot use their nose to tell the two apart. That is why ventilation here is an engineering control and not a comfort measure.

And the second removal: HARMAN records odour: Not known in section 9, so the maker publishes no description of what its own product smells like, which means a reader has no baseline against which to notice a change.

No acid, ever, anywhere near this bath, its tray, its bottle or its waste, and a thorough rinse between the toner and anything acidic in the sequence.

Storage

The concentrate: full, unopened, tightly sealed, cool, locked, and away from food. HARMAN’s own figures are two years for a full unopened bottle stored at 5 to 20 °C (41 to 68 °F), and use completely within six months once opened. The safety data sheet’s storage entry is laconic — ambient temperature, stable under normal conditions, incompatible materials none known — but its precautionary statement is not: P405, store locked up, which the 2010 technical sheet repeats as “keep locked up and out of reach of children”. That is a stronger storage instruction than any other photochemical in this formulary carries, and it is on both of the maker’s documents.

Keep away from food, drink and animal feeding stuffs, in the technical sheet’s own words, and separated from strong acids, which is the international safety card’s instruction for the selenite itself. The safety card adds one more that is worth taking literally on a darkroom shelf: store in an area without drain or sewer access.

The working solution keeps well and its three figures are about air, not about chemistry. Up to six months in a full, tightly capped bottle; one month in a half-full one — the clock starts when the air space appears, not when the seal breaks; up to seven days in an open tray. A bath that is a week old in a tray and a bath that is five months old in a full bottle are both within the maker’s limits, and the difference between them is entirely how much air they have met.

Buy for the darkroom you have. The six-month figure after opening is the binding one for most printers. A bottle bought for a single archival session and opened is on a six-month clock whatever is left in it.

Label everything — the product, the dilution and the date mixed — using the labelling SOP. This bath has no indicator, no distinguishing colour that its maker will describe, and no smell that can be trusted as a warning, so the label is the only thing that identifies it. An unlabelled or undated container is worse here than for any other tray in the sequence, because the failure mode is a selenium-bearing liquid nobody can identify.

On its own shelf, not the acid shelf, and not with photographic materials in the room.

Incompatibilities

Acids of every kind, and this one governs everything else. Selenite and acid generate a toxic hazard, the international safety card and CAMEO both say so without naming the gas, and the family’s volatile hydride is controlled at 0.02 ppm. No acid stop bath and no acid fixer follows this toner without a thorough wash between. No acid goes into its waste bottle. No acid is stored above it.

Stop baths and acid fixers, as the particular case a darkroom actually meets. ILFORD’s own sequence puts the toner after the fixer, so the risk is carry-over on tongs and fingers and the control is the holding dish HARMAN already specifies. The incompatibilities page governs.

The waste container, which is where the incompatibility usually happens. Spent stop bath and spent toner in the same bottle is the reaction nobody intended. Separate, labelled containers, always.

Metal trays and tanks, per Kodak’s general toning guidance, which forbids them for every toner.

Food, drink and animal feeding stuffs, in HARMAN’s own words on the technical sheet — a phrase ILFORD prints for this product and not for its developers.

Developer, in either direction, and unexposed photographic materials in the room.

✕What sections 7.2 and 10.5 say, and why they are not the last word

Section 7.2 gives incompatible materials as “None known” and section 10.5 gives them as “Not known”. Read literally, that says a bottle containing a selenite has no chemical incompatibilities, in a room whose next tray down is an acid stop bath.

A safety data sheet answers a narrow question — what makes this product itself unstable or dangerous, in its own sealed container — and it answers it well. It is not a compatibility chart for a process, and HARMAN’s identically-worded ILFOSTOP sheet has the same two lines. The course’s incompatibilities page governs, the international safety card for sodium selenite is explicit about strong acids where this sheet is silent, and HARMAN’s own technical sheet — which tells you to keep the product away from food and out of the drains — is the operative instruction.

Waste

Three streams in one bottle: selenium, silver and thiosulfate. That combination is what makes this the most tightly constrained waste on any ILFORD sheet in this corpus.

HARMAN’s own technical sheet is the strictest disposal instruction ILFORD prints for anything: “Do not empty into drains, dispose of this material and its container at hazardous or special waste collection point”, and rubber gloves in all use and disposal. Its safety data sheet says the same thing with an extra route: send to a licensed recycler, reclaimer or incinerator, dispose of the material and its container to a hazardous or special waste collection point, in accordance with local, state or national legislation. Section 6 adds that spillages or uncontrolled discharges into watercourses must be alerted to the appropriate regulatory body, and that spillages are adsorbed onto and contained with sand, earth or another suitable adsorbent.

Kodak’s independent guidance for amateurs points the same way and is worth quoting for its completeness. In its table of routes for amateur photographic chemicals, used Rapid Selenium Toner is given no sewer discharge, no discharge to a treatment works and no disposal with refuse — every route withheld except household hazardous waste collection. It is one of very few entries in that table treated that way.

Why the ecological classification understates it. The mixture is Aquatic Chronic 3, H412, harmful to aquatic life with long lasting effects, with the invertebrate, fish and algal figures all recorded as Not known. The selenite in it is Aquatic Acute 1 and Aquatic Chronic 1, H400 and H410, very toxic to aquatic life. The international safety card adds that selenite bioaccumulates along food chains, particularly in plants and fish. The dilution that softens the label does not soften the element.

Never acidified, and never combined with any acid stream. This is the same rule as the tray rule and it is the one most often broken at the sink.

What ILFORD tells United Kingdom domestic users: bottle each waste chemical separately, label it appropriately, and take it to the chemical cupboard at a Household Waste and Recycling Centre; a few authorities collect on request. Its instruction to business users is the same rule stated more strongly — different waste chemicals should not be mixed, and should be kept in separate, appropriately labelled containers.

The silver in it is a complication, not an opportunity. A used toning bath carries dissolved silver as well as selenium, so the silver-bearing waste SOP applies alongside the general chemical waste SOP. Whether a silver refiner will accept a selenium-bearing stream is a question for the refiner, and this course does not answer it.

The disposal caveat governs and local regulation decides.

Troubleshooting

Nothing visible happened. Ask which dilution first. At 1+20 on a neutral or cold-tone paper, nothing visible is the intended result — ILFORD recommends selenium on three of its own papers precisely because it has little effect on their image colour. If it was 1+3 on a warm-tone paper and still nothing moved, the next question is the bath’s age: HARMAN’s own exhaustion model is that the rate of tonal change becomes progressively slower with use and age, so an old bath does not fail, it crawls.

The toning is getting slower session by session. That is the maker’s published behaviour rather than a fault. Time a standard test print rather than trusting the count; the 25-sheets-per-litre figure is an “at least” for a dilution most archival printers do not use.

Uneven tone, patchiness or mottle. Start at uneven toning and mottle revealed after toning. HARMAN’s own prevention is on the sheet and is easy to skip: agitate for the whole period by gently rocking the dish, and slide the print in quickly rather than lowering it.

Round purple stains that appear only after toning. Air bubbles trapped between prints during fixing — Kodak names this specifically as a defect that shows up only after selenium or sulfide toning. Purple spots from fixer air bubbles is the entry, and the fix is upstream in the fixer, not in the toner.

Yellow staining, uneven tone or later fading, all together. Residual silver salts and traces of hypo, which Kodak names as the cause and which is a fixing and washing failure rather than a toning one. Residual thiosulfate, residual silver and yellow staining and yellow-brown highlight stain from residual silver have the diagnosis, and the residual hypo and silver tests will tell you before you tone rather than after.

A dark line creeping in from the edges of a resin-coated print. Toner edge penetration on RC.

The tone kept going after the print left the bath. Expected, and both makers say so. HARMAN’s answer is thirty to forty seconds of agitation in the second water dish; Kodak’s is to pull the print when it has almost the required tone.

A sharp garlic-like smell. Leave the room and ventilate it. Do not investigate the tray first.

A rash or irritation that appears after several sessions rather than after one. Treat it as sensitisation, not as an accident: stop using the product, get medical advice, and read the H317 paragraph in Safety again. This is the one failure on this page that does not get better with technique.

Two bottles on the shelf and no label. An unlabelled or undated container is the entry, and on this shelf it is a disposal problem rather than an inconvenience.

Experiments

Measure the pH HARMAN does not publish. Mix a litre at 1+20 and a litre at 1+3, calibrate a meter that day with the calibration SOP, and record both. The maker records pH as Not known on its own hazard sheet; you can have the number in five minutes, and knowing whether your bath sits well on the alkaline side is the single most safety-relevant measurement on this page. Record it against every later bottle.

Find out whether the toner really is a weak fixer. The inference above is the course’s and it is testable. A clip of unexposed, undeveloped film in a small volume of working-strength toner, timed to clear, against an identical clip in working-strength RAPID FIXER, using the clearing time test. A clearing time — even a very long one — converts a reading of a composition table into a measurement. No clearing at all is an equally publishable result.

Measure the intensification the maker claims and does not quantify. A step wedge on your paper, processed identically, half toned at 1+20 for four minutes and half not, read on a densitometer. HARMAN’s claim is enhanced maximum density; this is that claim as two curves on the paper you actually use, and it is the experiment Part XX will ask for when it is written.

Find where partial conversion sits. Identical prints pulled at 1, 2, 4 and 8 minutes at 1+20. Moersch’s observation is that a selenium bath has not converted all the silver even at six minutes; the visible consequence is that every selenium-toned print is a mixture, and the printer chooses the proportions without measuring them.

Three papers in one tray. Warm-tone, neutral and cold-tone, toned together at 1+3 for the same time. HARMAN’s three predicted outcomes — cool chocolate, purplish brown, and nothing discernible — are the clearest demonstration in this formulary that a toner’s colour belongs to the paper.

Test HARMAN’s own exhaustion model. The sheet says the bath slows rather than stops. Tone one standard test print to a fixed visible change, timing it, at the start of a litre’s life and after every fifth sheet through it. Plot time against cumulative sheets. If the curve rises smoothly, the maker’s model is right and the 25-sheet figure is a convention; if it turns sharply, you have found something the sheet does not describe.

Run the two diluents against each other. HARMAN’s toner sheet says dilute with water. Four ILFORD paper sheets say dilute with working-strength WASHAID instead. Neither document acknowledges the other. Two matched prints, two baths, the same time, then the full archival print sequence on both — and a residual-hypo test on each, because the sequence exists for permanence rather than for colour.

This against the open protective formula. GP-1 is gold, published in full, at Level B, for the same archival purpose. Matched prints, one in each, judged for colour shift and read for D-max. The comparison is worth making because GP-1 is what this page would recommend if the argument were only about openness, and it is not: it is about cost, colour and what a printer can actually get.

Record all of it. A bought product earns a line in the formula version record as much as a mixed one does — the dilution, the bottle’s purchase and opening dates, and how many sheets the bath had already taken — because on a product whose composition is secret, your own bath’s history is the only variable you control and the only one you can prove.