ILFORD MULTIGRADE developer

This is the first page in the formulary that is not a formula, and the difference is the point of it. Everything else in this library is a list of quantities with a source attached and an account of what each quantity is doing. Nobody outside Harman knows the quantities in this bottle. What follows is what its maker publishes, which for dilution, time, capacity, keeping and even pH is a great deal; what its maker’s own safety data sheet discloses, which is more than most; what the two documents together still leave unknown; and the open formula to mix if you would rather know than buy.

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
WaterCAS 7732-18-5The bulk of the concentrate; the sheet classifies it as not classified	73.5138
Sodium sulfite (anhydrous)named on the sheet as Sodium sulphiteCAS 7757-83-7	10-30%
Potassium carbonate (anhydrous)named on the sheet as Potassium carbonateCAS 584-08-7	5-10%	H315, H319, H335
pentasodium (carboxylatomethyl)iminobis(ethylenenitrilo)tetraacetateCAS 140-01-2	<3%	H332, H361, H373
Hydroquinonenamed on the sheet as 1,4-dihydroxybenzenehydroquinonequinolCAS 123-31-9One of the two developing agents ILFORD names in the product description	<2.5%	H302, H317, H318, H341, H351, H400, H410
Sodium hydroxidenamed on the sheet as sodium hydroxidecaustic sodaCAS 1310-73-2	<1%	H290, H314, H318
Dimezone Snamed on the sheet as 4-(hydroxymethyl)-4-methyl-1-phenylpyrazolidin-3-oneCAS 13047-13-7The other developing agent ILFORD names; the product description calls the developer a dimezone-s/hydroquinone one	<1%	H302
BenzotriazoleCAS 95-14-7Named as present, with no concentration given	—
Potassium bromideCAS 7758-02-3Named in the regulatory section and not in the composition table, with no concentration given	—

Not disclosed. HARMAN publishes no composition for MULTIGRADE developer. The safety data sheet names seven components and gives each a concentration band for the purpose of classifying a hazard, which is not an assay: the bands are wide, their upper limits sum to more than the whole bottle, and two further substances the sheet names elsewhere carry no figure at all. No quantity, no ratio between the two developing agents, no buffer system, no sequestrant loading and no formulation date is published anywhere in ILFORD's literature. A reader who needs to change one term at a time, and see what it does, has to mix an open formula instead of buying this one.

Nearest open formula. Kodak D-72 — Both are alkaline superadditive paper developers meant for a dish at 20 degrees C, and they do the same job on the same papers. D-72 is published in full and mixed from five weighed chemicals whose functions can each be named; MULTIGRADE is a bought concentrate whose maker names two developing agents and nothing else. D-72 uses metol with a large excess of hydroquinone in sodium carbonate, diluted one in four for bromide enlarging papers; MULTIGRADE uses a pyrazolidone with hydroquinone at one in nine or one in fourteen, develops a resin-coated print in a minute against Kodak's minute and a half, and publishes a working pH, a capacity in prints per litre and four keeping figures where Kodak's two printings give no pH and no print capacity at all. The exchange is convenience and published performance against the ability to change one ingredient and see what happens.

Purpose

To develop a black and white print, on any ILFORD paper and on most other makers’, to full black in one to three minutes at ordinary room temperature, from a bottle that keeps for two years unopened. ILFORD describes it as “a rapid liquid concentrate dimezone-s/hydroquinone developer suitable for the dish/tray developing of all black and white photographic papers both resin coated, RC, and traditional fibre based, FB ones”, clean working, with excellent keeping properties and a neutral image tone with most papers.

Three of those words are the whole product. Rapid: a resin-coated print is finished in a minute, against the two minutes ILFORD gives its own PQ UNIVERSAL and BROMOPHEN. Liquid concentrate: you measure a volume rather than weigh a powder, which removes the two operations that make mixing a print developer a job — weighing a sensitiser, and dissolving it in the right order. Neutral: it is not a toning developer and is not offered as one; ILFORD sends you to BROMOPHEN when you want warmth.

Recommended uses

Dish or tray printing at 20 °C, at 1+9, made up for the session and thrown away at the end of it. That is the use ILFORD documents and the one every published figure on this page belongs to. The sheet asks for the working solution to be prepared directly before it is needed, for enough of it to fill the dish about half full, and for all the process solutions to be within one degree of the working temperature.

At 1+14 when you want longer in the tray. ILFORD offers the second dilution “for greater development control and economy”. A minute is a short time to be moving a sheet about evenly, and ninety seconds is easier; on fibre the recommended time goes from two minutes to three. What you pay is capacity — a hundred resin-coated prints a litre becomes seventy.

With the interleaving method when you are printing a batch. The sheet’s own instruction for multiple sheets is to slide them into the dish one at a time emulsion side down, then repeatedly pull the bottom sheet to the top of the pile until the time is up, and to lift the print out ten seconds before the end so it can drain. Fibre paper goes limp when wet and is harder to interleave than the resin-coated base, which stays rigid.

Not for film. ILFORD states flatly that MULTIGRADE developer is not suitable for developing films, and that it is not designed for high-temperature or machine processing. Its stablemate PQ UNIVERSAL is the one that doubles as a dish film developer; this one does not.

When another formula is preferable

• When you want to understand a print developer rather than use one, mix D-72. It is the same job done by five chemicals you can name, weigh and change, and it is the comparison this page is built around.
• For a deliberately warm image tone, ILFORD’s own answer is BROMOPHEN on Warmtone papers, and the course’s open answers are D-156 and, warmer still, D-166 with twelve and a half grams of bromide to the litre.
• For soft, open highlights with no restrainer in the bath at all, D-52 leaves the bromide out of the stock and puts it in the reader’s hands as an optional addition.
• For one bottle that develops both prints and negatives, D-163 is a universal developer with two published dilutions, and ILFORD’s PQ UNIVERSAL is the bought equivalent.
• For the coldest blue-blacks a bath can give, D-170 is an amidol developer with no alkali in it at all, and nothing bought will imitate it.
• When the darkroom is not at 20 °C and cannot be brought there. ILFORD is explicit that this developer is designed for ambient room temperature and that high temperatures reduce the solution life considerably and shorten development to the point where uneven processing appears. A developer you mix yourself can be adjusted; a concentrate formulated for 20 °C cannot.

What the maker publishes

More than most makers do, and it is worth setting out in full because the amount of it is the reason a product page can be useful at all.

The pH, which is the rarest of these figures. ILFORD prints a table of pH and specific gravity for fresh solutions: MULTIGRADE at 1+9 reads 10.45 to 10.55 with a specific gravity of 1.022 at 20 °C. At 1+14 the sheet gives a specific gravity of 1.011 and no pH at all, which is a gap and not a rounding. ILFORD adds that the figures were obtained under controlled laboratory conditions, that a user’s own measurements may differ slightly, and that the right use of the table is to make your own control measurement on your own fresh solution and compare later ones against it. That is better advice than the number.

The times, for two paper bases and two dilutions, with a recommended figure and a range around it on fibre: one minute for resin-coated at 1+9, ninety seconds at 1+14; two minutes for fibre at 1+9 within a range of one and a half to three, and three minutes at 1+14 within a range of two to five. MULTIGRADE RC COOLTONE gets approximately double the resin-coated time to reach the coolest image colour.

The plateau. ILFORD states that development “may be extended to 6 minutes without any noticeable change in contrast or fog”. That single sentence is worth more than the recommended time, because it tells you the recommended time sits inside a wide flat region and not on a slope — Part XVIII draws the two curves that make it true.

The emergence time, which is the number you actually watch in the dark. On a correctly exposed print at 1+9 ILFORD says the image begins to appear at approximately 10 seconds on resin-coated paper. On fibre its two sheets disagree: the developer sheet says 35 seconds and the MULTIGRADE FB CLASSIC sheet says approximately 20. Treat 20 to 35 seconds as the band the maker’s own literature supports, and treat your own measured figure as the one that matters.

The capacity, per litre of working solution and per litre of concentrate: 100 resin-coated or 50 fibre 8 × 10 prints from a litre at 1+9, 70 and 40 at 1+14, about half those figures if all you process is COOLTONE, and 1000 resin-coated or 500 fibre sheets from a whole litre of the concentrate.

The keeping, in four figures: two years for a full unopened bottle stored at 5 to 20 °C, six months to use up an opened one, one working day for working solution in an open dish, and 24 hours for working solution in a tightly capped bottle.

The water advice, which is easy to miss and is chemistry: most water drawn from a pressure main is highly aerated, so ILFORD asks you to draw off what you need and let it stand a few minutes before making up a developer with it.

What is not disclosed

The formula. Not the quantity of any ingredient, not the ratio between the two developing agents, not the identity or loading of the alkali buffer, not the restrainer level, not the sequestrant level, and not the date the current formulation was fixed. ILFORD names two developing agents in a product description and stops.

Anything measurable that would let you infer it. Section 9 of the safety data sheet is a column of the words Not known — appearance is “Liquid”, colour not known, odour not known, pH not known, density not known, solubility not known. The maker that publishes a pH band for the diluted working solution in its technical sheet declines to publish one for the concentrate in its hazard sheet.

!Why the bands in the table cannot be added up

The temptation with a composition table is to treat the percentages as an assay and solve for the rest. Do the arithmetic once and the temptation goes away.

Add the upper limits of the six bands to the water figure and you get about 121 per cent, which is more than a bottle. Add the lower limits — four of the six are open-ended, so only the sulphite and the carbonate contribute anything — and you get about 88.5 per cent, leaving more than a tenth of the product unaccounted for by any named substance. Both totals are the course’s arithmetic on ILFORD’s own printed figures, and neither is a composition.

That is not sloppiness on HARMAN’s part. A concentration band on a safety data sheet exists to support a classification: it is chosen so that the mixture’s hazard can be calculated conservatively, and a band wide enough to do that is far too wide to mix from. A safety data sheet read as a hazard document is evidence. Reassembled into a recipe it is a fabrication with citations attached, and this page does not attempt it.

Two of the nine components have no figure at all. Benzotriazole and potassium bromide are named by the sheet outside the composition table — one under other hazards, both in the regulatory section — and neither carries a percentage. They are present; how much is present is not published.

Nothing about why. No source in the corpus says why Dimezone S replaced Phenidone in ILFORD’s liquid concentrates, why this developer runs at 10.5 rather than 10.2 or 10.8, or what makes it twice as fast on paper as the company’s own PQ UNIVERSAL. Those are the interesting questions and the literature does not touch them.

Disclosed components

Every component in the table above, in the order the safety data sheet prints them. The concentration against each is the band the sheet states and not a quantity, and the function line is given only where the maker says so or where the identification is not in doubt.

Water, CAS 7732-18-5, 73.5138. The largest single entry and the strangest. Every other component gets a band; water gets a number to four decimal places, in a column headed % W/W, with no band and no tolerance. It is the shape of a figure that fell out of a formulation calculation rather than a classification, and it is the only place in either document where the composition of the concentrate is given a precise number. It buys a reader nothing on its own, for the reason set out above.

Sodium sulphite, CAS 7757-83-7, 10-30 %. Sodium sulfite is the second entry on the sheet and carries much the widest band on it, a factor of three from end to end. In a print developer its established work is preservation: it consumes dissolved oxygen and intercepts the quinone that hydroquinone becomes, which is what Part VIII’s lesson on sulfite and preservation sets out. In a concentrate that has to survive two years unopened and six months in use with a growing air space above it, that job is a larger one than in a developer mixed for the evening — the course’s reading, not ILFORD’s. The sheet classifies the substance as not classified, gives it no function, and the course does not turn a band that wide into a concentration.

Potassium carbonate, CAS 584-08-7, 5-10 %. Potassium carbonate is the third entry on the sheet and carries its respiratory-irritant classification, H315, H319 and H335. Carbonate against bicarbonate is a genuine buffer pair, and a buffer is what a paper developer needs: a print developer is a tray open to the air that must hold its pH through a hundred prints, each of which puts acid into the bath as it develops. The identification of carbonate as the buffering alkali here is the course’s reading of a component list and is not an ILFORD statement.

pentasodium (carboxylatomethyl)iminobis(ethylenenitrilo)tetraacetate, CAS 140-01-2, less than 3 %. The name is a mouthful and the substance is familiar: the pentasodium salt of diethylenetriaminepentaacetic acid, DTPA, a chelating agent from the same family as the EDTA salts the course meets elsewhere. It is the only component with no plausible photographic role except sequestration — holding calcium, magnesium and above all iron out of circulation so that hard tap water does not precipitate in the tray or catalyse the oxidation of the developing agents. It carries a reproductive-toxicity classification, H361, alongside H332 and H373 — and the mixture as a whole is not classified for reproductive toxicity, which is what a band below 3 per cent buys and is a small lesson in how the two halves of a sheet relate. ILFORD states no function for the substance and neither does the sheet; its class is not in doubt and the reason for its presence in this particular product is an inference.

1,4-dihydroxybenzenehydroquinonequinol, CAS 123-31-9, less than 2.5 %. This is hydroquinone, and the mangled name is the sheet’s own: it runs three synonyms together with no separator between them. It is the component that gives the mixture almost all of its hazard classification — H302, H317, H318, H341, H351, H400 and H410 — and it is the reason the product is labelled a suspected mutagen and a suspected carcinogen at all. It is also one of the two developing agents ILFORD names. The sheet prints its components in descending order of concentration and puts hydroquinone above the pyrazolidone in a wider band, which reads as the larger of the two agents — a reading of the table’s order, not a statement in it, since one open-ended band cannot be compared with another.

sodium hydroxidecaustic soda, CAS 1310-73-2, less than 1 %. Sodium hydroxide — again with two synonyms run together — is the only component classified as corrosive, 1A, and the only one with a metal-corrosion classification. Below one per cent of a concentrate that is then diluted nine or fourteen times, it is not what makes the working solution dangerous; what it is doing is setting a pH that carbonate alone would not reach. That reading is an inference from where hydroxide appears in developer formulation generally, and ILFORD does not say it.

4-(hydroxymethyl)-4-methyl-1-phenylpyrazolidin-3-one, CAS 13047-13-7, less than 1 %. This is Dimezone S, and here the maker does tell you what it is for: the product description calls MULTIGRADE a dimezone-s/hydroquinone developer. It shares the sheet’s narrowest band with the sodium hydroxide and is the substance that makes the developer work, which is the signature of a superadditive pair. The chemical page has the full account of the substance and of what ILFORD does and does not say about the substitution for Phenidone.

Benzotriazole, CAS 95-14-7, no concentration given. The sheet names benzotriazole twice outside the composition table: section 2.3 states that “this product contains: 95-14-7 (Endocrine disrupting properties)”, and section 12.6 records it as listed for evaluation for endocrine disruption under EU legislation. It is an organic antifoggant — the substance Part VIII’s lesson on restrainers treats as the one that holds fog down without the shadow-speed penalty a bromide exacts. That it is present is the maker’s statement. How much, and what it is doing here, is not published.

Potassium bromide, CAS 7758-02-3, no concentration given. Potassium bromide appears in one place only: the Annex XVII line in section 15, where the sheet lists the substances in the product that appear on a UK REACH restrictions list. Every other name on that line is a component from the composition table, so the course reads its presence there as HARMAN naming a constituent. That is a reading of the document’s structure and not a statement in the composition table, and it is marked as such here and in the table above. A paper developer containing bromide is entirely ordinary; the interest is that the sheet’s own regulatory section discloses a component its composition section does not.

Behaviour

It is fast, and the speed is the product. A minute for a resin-coated print at 1+9 is half what ILFORD asks for its own PQ UNIVERSAL and BROMOPHEN, and two thirds of the minute and a half Kodak publishes for D-72 on a bromide enlarging paper. The comparison only goes so far — Kodak’s times are for the papers of 1928, and its 45 seconds on a chloride contact paper is faster than either — but for a printer making a test strip, a work print, another work print and a final print, a minute against two compounds through an evening.

It works to completion, not to a target density. This is the single largest difference between printing and film development and it is where beginners lose prints. The recommended time is a point inside a plateau: ILFORD’s six-minute claim says the maximum black has stopped rising and the base has not yet begun to lift, so a print left a minute longer looks the same and a print pulled early does not look lighter — it looks underdeveloped, weak in the blacks and mottled where the developer first reached the sheet.

It exhausts by counting, not by looking. A hundred 8 × 10 resin-coated prints to a litre is a capacity, and the useful discipline is to count sheets rather than to judge the colour of the tray. The published figure halves on fibre paper, which soaks up far more solution and carries more of it away, and halves again if the paper is COOLTONE and getting twice the time.

It does not survive the night. One working day in an open dish, 24 hours in a capped bottle. There is no replenishment scheme, no starter and no seasoning: the working solution is made for the session and poured away after it. The two-year keeping figure belongs to the sealed concentrate and to nothing else.

It is formulated for one temperature. ILFORD’s tolerance is 20 °C ± 1 °C. Slightly cooler works with a slightly longer time; hotter shortens the time to the point where an even development becomes difficult, and reduces the solution life considerably.

⚗What the published pH is actually telling you

10.45 to 10.55 sits nearly two pH units above the 8.60 to 8.70 ILFORD publishes for its own ID-11 film developer, and every pH unit is a factor of ten in hydroxide-ion concentration. That gap is what makes a print develop in a minute and a film take ten, and Part VIII’s lesson on alkalis and buffers works through why: a developing agent works as its anion, and the fraction ionised is set by the pH against the agent’s pK_a. At 10.5 hydroquinone is substantially ionised. At 8.6 it is barely started.

Use the band as a control measurement rather than as a fact about your bath. ILFORD’s own advice is to measure your own fresh solution and compare later ones to it, and the pH meter calibration procedure is what makes that reading worth anything.

Image characteristics

Image tone: neutral, on most papers. This is ILFORD’s own word and it is a claim about the product rather than a measurement. The company’s warm-tone recommendation is a different developer entirely, which is a useful signal: a maker that tells you to buy its other product for warmth is telling you this one will not give it.

Contrast: not adjustable by development. The plateau claim — six minutes with no noticeable change in contrast or fog — means that on a variable-contrast paper the contrast control is the filtration and the exposure, not the tray. That is a feature and not a limitation; it is what makes split-grade printing repeatable.

Maximum black: reached, and reached quickly. The sensitometric curves ILFORD publishes for MULTIGRADE FB CLASSIC were made in this developer at 1+9 for two minutes at 20 °C, which means the paper’s published characteristic curves are, strictly, curves of a paper-and-developer pair. Change the developer and you have left the published curve behind.

Fog: low, and the whites are the thing to watch. “Clean working” is the maker’s phrase for it. The disclosed presence of both an organic antifoggant and a bromide is consistent with a bath built to hold its whites through a long session, though how much of either is present is not published.

Grain, acutance and film speed do not apply. This is a paper developer and ILFORD says plainly it is not for film.

The mechanism

Everything in this section that goes beyond the two agent names is marked as what it is.

What the maker states. MULTIGRADE developer is a dimezone-s/hydroquinone developer used at 1+9 or 1+14, working at pH 10.45 to 10.55 at the first dilution, developing a print in one to three minutes at 20 °C, and holding contrast and fog steady out to six.

What follows from that without needing anything else: it is a PQ developer. A pyrazolidone with hydroquinone is the modern form of the superadditive pair, and the pair is the central mechanism of Part VIII’s superadditivity lesson. The fast agent — here Dimezone S, a 1-phenylpyrazolidin-3-one with two substituents on the ring — reduces silver at the latent-image site and is itself oxidised; the hydroquinone, present in much the larger quantity, regenerates it from solution. The consequence a printer can see is that a very small amount of one substance transforms the behaviour of a much larger amount of another, which is consistent with the pyrazolidone sitting in the narrowest band the sheet prints and the hydroquinone in a wider one, although two open-ended bands are not a ratio and this page does not treat them as one.

Inference, labelled as inference. The regeneration account of superadditivity is the standard one and no source in this course’s corpus states it for this product. The identification of potassium carbonate as the buffering alkali and sodium hydroxide as the agent that lifts the pH to 10.5 follows from what those substances do in developers generally and is not an ILFORD statement. The reading of the DTPA salt as a sequestrant against hard water is an inference from its class. The reading of benzotriazole and potassium bromide as the antifogging pair is an inference from where each substance sits in developer chemistry; ILFORD names them and says nothing about their purpose.

What is unknown and stays unknown. The ratio of Dimezone S to hydroquinone. Kendall’s 1942 Ilford patent gives the quantitative claim for phenidone — that about a fifth to a sixth of the metol’s weight substitutes for it — and the Dimezone S page is explicit that no source gives a ratio for this molecule, so the course does not transfer it. Also unknown: the carbonate-to-hydroxide balance, the sulfite concentration within a band spanning a factor of three, the antifoggant loading, and whether the formulation sold today is the one the 2010 technical sheet was written for.

!Reading a safety data sheet, and what its defects teach

This sheet has two visible faults, and noticing them is part of the skill the course is trying to build.

It runs synonyms together. Hydroquinone is printed as “1,4-dihydroxybenzenehydroquinonequinol” and sodium hydroxide as “sodium hydroxidecaustic soda”: three synonyms and two synonyms concatenated with no separator. A reader who does not already know the substances would struggle to look either of them up. The CAS number is the field to trust, every time, and it is why every line in the table above carries one.

Its dates do not agree. The sheet gives a date of issue of 18 July 2024 and a date of revision of 17 July 2027, three years in the future. That is almost certainly a review date printed in the wrong field, and it is exactly the kind of thing to record when you file a sheet rather than to correct silently. The course’s procedure for that is recording a safety data sheet.

The nearest open formula

Kodak D-72, and the comparison is the reason this page exists.

D-72 is the archetype alkaline paper developer: metol and a large excess of hydroquinone in sodium carbonate, with potassium bromide as the restrainer, mixed from five weighed chemicals and diluted one in four for bromide enlarging papers, one in two for Azo and one in one for Velox. MULTIGRADE is the same class of bath — an alkaline superadditive developer worked in a dish at 20 °C — arriving as a liquid instead of a powder and with a pyrazolidone in place of the metol.

	Kodak D-72	ILFORD MULTIGRADE developer
Composition	Published in full, twice, twenty-one years apart	Not published
Developing pair	Metol and hydroquinone	Dimezone S and hydroquinone, both named by the maker
Alkali	Sodium carbonate, quantity published	Potassium carbonate and sodium hydroxide named; no quantities, and which of them buffers is inferred
Restrainer	Potassium bromide, quantity published	Potassium bromide and benzotriazole named as present; no quantities, and the role is inferred
Working dilution	1:4 for bromide enlarging papers	1+9, or 1+14 for more control
Published pH	None, in either printing	10.45 to 10.55 at 1+9
Published paper time	1½ minutes at 1:4 on bromide enlarging paper, at 21 °C	1 minute at 1+9 on resin-coated, at 20 °C
Capacity in prints	None published in either Kodak printing	100 resin-coated or 50 fibre 8 × 10 per litre
What you can change	Any of five quantities, one at a time	The dilution, the time and the temperature

The last row is the whole argument. Buying the concentrate gets you a faster, longer-lived bath with a published capacity and a published pH, and it gets you exactly three variables. Mixing D-72 gets you a bath with no published capacity and no published pH, and eight variables, five of which are quantities you chose. Part XVIII’s comparison session puts the two in adjacent trays with the same negative, which is the only way to find out what the difference is worth to you.

Safety

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

The mixture as HARMAN classifies it is Skin Sens. 1B, Eye Irrit. 2, Muta. 2, Carc. 2 and Aquatic Chronic 3, signal word Warning, with H317, H319, H341, H351 and H412. Skin sensitisation is what pushes it past Level A on the classification rubric: sensitisation is not reversible, and a Level A page assumes substances that are at most irritant at the concentrations handled. The suspected-mutagen and suspected-carcinogen classifications are read against the Level C criterion and do not meet it, because that criterion turns on a fume cupboard or specialist disposal being the recognised control, and HARMAN’s own control is ordinary ventilation, gloves and eye protection: section 8 of the sheet states that no personal respiratory protection is normally necessary. Level B, therefore, with the concentrate as the reason rather than the tray.

The concentrate is the hazardous part of the job. It is where the hydroquinone is at its highest concentration, where the sodium hydroxide is, and where a splash carries the whole classification. Decant it over the sink, not over the bench, and never over the paper safe.

Personal protection, as the sheet specifies it. Eye protection with side protection to EN ISO 16321-1. Impervious gloves to EN 374, with the breakthrough time taken from the glove maker rather than assumed — the course’s glove selection page is where that goes. Protective clothing. Hands and exposed skin washed thoroughly after handling, and contaminated clothing taken off and washed before it is worn again.

Ventilation and eyewash. The sheet asks for use with ventilation or local exhaust ventilation, and for a washing facility for eye and skin cleaning to be present. A darkroom with an extractor running and an eyewash bottle within reach meets that; a sealed bathroom does not.

Print tongs, not fingers. The exposure that causes sensitisation is the repeated small one, not the dramatic one, and a printer who fishes prints out by hand for an evening has had a great deal more contact than one splash would give.

Published exposure limits, quoted by the sheet from EH40/2005: hydroquinone at 0.5 mg/m³ as a long-term eight-hour limit, and sodium hydroxide at 2 mg/m³ as a short-term one. Both are workplace air limits for the pure substances and neither is a limit for a tray of diluted paper developer; they are here because the sheet prints them.

⚠The one line on the technical sheet to disagree with

ILFORD’s technical sheet opens its mixing instructions with the sentence “Photographic chemicals are not hazardous when used correctly.” The same company’s safety data sheet for this same product classifies it as a skin sensitiser, a suspected mutagen and a suspected carcinogen and instructs the user to store it locked up.

Both documents are HARMAN’s. The technical sheet’s own next sentence recommends gloves, eye protection and an apron and points the reader at the safety data sheets, so the intent is clear enough — but the wording is the kind that gets repeated in a darkroom until somebody stops wearing gloves. The classification is the fact. “Used correctly” is doing all the work in that sentence, and the safety data sheet is where it is defined.

Storage

The concentrate, in its own bottle, tightly capped, upright, at 5 to 20 °C and out of the light. Full and unopened it keeps two years; once opened, ILFORD asks for it to be used up within six months and for the cap to go back on every time. The safety data sheet adds one instruction the technical sheet does not: store locked up, which in a domestic darkroom means a cupboard a child cannot open.

Buy the bottle size you will use. ILFORD sells 500 mL, 1 L, 2.5 L and 5 L bottles and a 10 L bag in box. The six-month clock starts when the seal breaks, and a five-litre bottle bought for the saving is a five-litre bottle with a growing air space above it. A bag in box collapses as it empties instead of filling with air, which would answer that problem exactly; ILFORD lists the pack and does not say why it exists, so the reason is the course’s and not the maker’s.

The working solution is not stored. Make it for the session, and pour it away at the end of the day. Twenty-four hours in a capped bottle is the outside figure and the sheet gives it as a concession, not a plan.

Label everything, with the product, the dilution and the date mixed, using the labelling SOP. A tray of clear liquid in a darkroom is indistinguishable from three other trays of clear liquid, and an unlabelled or undated container is the failure that costs a whole printing session.

Incompatibilities

Acid, and specifically the stop bath. ILFORD’s own instruction is not to contaminate developer solutions with either stop bath or fixer, and to wash all utensils after use. A splash of acetic or citric acid carried back on a pair of tongs does not merely dilute this developer, it takes it out of the pH region where it works.

Fixer, in both directions. Thiosulfate in the developer tray silver-solvents and stains; developer carried into the fixer shortens its life and stains prints. It is also a waste problem, because paper developer carries negligible silver and mixing it into the fixer spoils a solution that would otherwise go for recovery.

Strong oxidisers. Ferricyanide, dichromate, permanganate and persulfate must never meet a developing agent on a shelf or in a drain. The chemical incompatibilities page sets out the pairs and the reactions.

Metals, for the concentrate. The sodium hydroxide component carries H290, may be corrosive to metals. The mixture as a whole is not classified that way, but there is no reason to keep the concentrate in anything but the bottle it came in.

✕What section 10 of the sheet says, and why it is not the last word

Section 10.5 of the safety data sheet gives incompatible materials as “Not known”, and section 7.2 gives them as “None known”. Read literally, that says a photographic developer has no chemical incompatibilities, which is false in a darkroom where the next tray is an acid and the one after it is a thiosulfate.

A safety data sheet answers a narrow question — what makes this product itself unstable or dangerous — and it answers it about the product in its container. It is not a compatibility chart for a process. The course’s own incompatibilities page governs here, and the maker’s technical sheet, which does tell you not to contaminate the developer with stop bath or fixer, is the relevant instruction.

Waste

Bottled separately, and not poured into the fixer. Spent paper developer is alkaline, carries negligible silver, and contains both developing agents in their oxidised forms. HARMAN classifies the product Aquatic Chronic 3, harmful to aquatic life with long lasting effects; its hydroquinone component alone is Aquatic Acute 1 and Aquatic Chronic 1, very toxic to aquatic life with long lasting effects. Section 6 of the sheet asks that spillages or uncontrolled discharges into watercourses be reported to the appropriate regulatory body, which is a strong hint about the drain.

What the sheet says to do with it: dispose of contents in accordance with local, state or national legislation, and send it to a licensed recycler, reclaimer or incinerator, or to a hazardous or special waste collection point.

What ILFORD tells United Kingdom domestic users: bottle each waste chemical separately, label it, and leave it in the chemical cupboard at a Household Waste and Recycling Centre.

The disposal caveat governs and local regulation decides. The general chemical waste SOP gives the procedure this course follows. Whatever the rule where you are, the developer bottle and the fixer bottle stay separate: one of them is worth money at a refiner and the other is not.

Troubleshooting

Prints weak in the blacks, slightly warm, and uneven. Almost always development snatched short of the recommended time rather than anything wrong with the bath — muddy print from snatched development has the full diagnosis. The bath is fine; the exposure is what needs to change.

The image takes far longer than 10 seconds to appear on resin-coated paper. Either the print is underexposed or the developer is going. Count the prints that have been through the litre against the published capacity before you blame the bath, then check the temperature, then mix fresh.

Grey where the paper should be white. Two candidates, and they are told apart by a strip of unexposed paper put straight into the developer. Developer fog on paper is the developer’s fault; safelight fog and paper storage fog are not.

Highlights grey and flat late in a session. Grey highlights from developer exhaustion. The published capacity is a manufacturer’s figure for their papers; yours is what you measure, and it will be lower with fibre paper and lower again if the tray has been standing.

Prints from one session do not match prints from the next. Check that the dilution was the same one — sixty millilitres into 540 is 1+9 and sixty into 840 is 1+14, and a misread dilution ratio changes the time by half and the capacity by a third. Then check the temperature. Then check the date on the concentrate.

The concentrate has gone dark in the bottle. Oxidation of the developing agents, which is what oxidised developer covers. A half-empty bottle past its six-month opened life should be treated as suspect and tested against a control strip before a print you care about goes in it.

Streaks in one direction across a fibre print. Not the developer. Uneven agitation, and usually interleaving too many sheets at once — ILFORD warns that too many sheets with too little agitation gives uneven processing. See mottled development.

Experiments

Measure the pH of a fresh 1+9 and compare it with ILFORD’s band. This is the cheapest possible calibration of your own meter and your own water, and it is the one ILFORD explicitly asks for. Do it with a meter calibrated that day — the calibration procedure is the whole experiment’s validity — and record the figure. Every later measurement is compared against your own first one, not against 10.45 to 10.55.

Test the six-minute plateau. Print five identical sheets from one negative at one exposure and develop them for 45 seconds, 1 minute, 2 minutes, 4 minutes and 6 minutes at 1+9. The prediction from the maker’s claim is that the last four are indistinguishable in maximum black and that only the first is weak. If the six-minute print has a grey base, you have found the far end of the plateau on your paper and your safelight, which is worth knowing.

Run the capacity down deliberately. Take a litre at 1+9 and put 8 × 10 prints through it in batches of ten, printing one identical control sheet at the start of each batch. Plot the maximum black of the controls against the number of prints. ILFORD says a hundred; the interest is in where your curve turns down, and whether it turns down before the whites lift or after.

1+9 against 1+14, with the published times. Two trays, one negative, matched exposures, one minute against ninety seconds on resin-coated paper. If the prints match, the dilution has cost you nothing but capacity and bought you thirty seconds of control. If they do not, you have found something ILFORD’s sheet does not mention.

The comparison that matters most: this against D-72. Same negative, same paper, same session, the bought concentrate at 1+9 and the mixed developer at 1:4, both at their published times, and note that Kodak’s is published for 21 °C and ILFORD’s for 20. Part XVIII’s session sets it up properly with a third arm and a control. Record it in the formula version record — a bought product gets a line in that record too, with its dilution, its bottle date and how many prints had already been through the tray, because those are the only three variables you have.

Log the emergence time on every print for a month. Write down the second the image appears, next to the print number and the age of the bath. It costs nothing, and by the end of the month you will have a diagnostic that tells you a bath is dying before a print does.