Kodak D-177

Three solutions, and the third of them is the second one diluted. Kodak Limited makes D-177’s pyro stock a hundred and fifty millilitres at a time — a concentrate at 83 grams of pyro to the litre, headed stock solution for storage — and then prints the dilution of that stock as a solution in its own right. It is the only formula in this formulary whose ingredient list contains one of its own solutions.

Solution A — the stock solution for storage - a concentrated pyro stock, kept acid

Ingredient	Quantity	Form the source specifies
Potassium metabisulfite	1.4 g
Pyrogallol	12.5 g	Kodak calls it pyro and defines it as 1:2:3 trihydroxybenzene
Potassium bromide	1.7 g
Water	to make 150 mL	A hundred and fifty millilitres, not a litre. The handbook's own heading for this solution is "stock solution for storage", and the whole 150 mL becomes Solution B when it is wanted.
Preservative first, which is the handbook's general rule wherever there is no Elon in the formula. Bromide is last and its position is immaterial: it has no action on the agent.

Solution B — Solution A, diluted to the strength it is used at

Ingredient	Quantity	Form the source specifies
Solution A	150 mL
Water	to make 1000 mL	Kodak's own line is "Solution A 150 c.c., water to make 1000 c.c.". This is a solution of the formula drawn from another solution of the same formula, and writing out A's three solids here instead would be the course's arithmetic in place of Kodak's line.

Solution C — the preservative and the alkali, together

Ingredient	Quantity	Form the source specifies
Sodium sulfite (anhydrous)	50 g or 100 g (crystalline, which is the handbook's main column)	anhydrous
Sodium carbonate (anhydrous)	37.5 g or 100 g (crystalline, which is the handbook's main column)	anhydrous
Water	to make 1000 mL	"Water to make 1000 c.c." No temperature is given; a solution carrying 200 g of crystals to the litre is far easier to make warm than cold, and must be cool before it is used.

Mixed in the ratio — negatives of average contrast

1 part Solution B + 1 part Solution C

For negatives of average contrast, use equal parts of Solutions B and C.

The working bath holds 6.25 g/L of pyro, 0.7 g/L of potassium metabisulphite, 0.85 g/L of potassium bromide, 25 g/L of anhydrous sodium sulphite and 18.75 g/L of anhydrous sodium carbonate.

Mixed in the ratio — portraits and softer negatives

1 part Solution B + 1 part Solution C + 2 parts water

For portraits and softer negatives, use equal parts of Solutions B and C and 2 parts of water.

Four parts in all, so every strength halves: 3.13 g/L of pyro, 12.5 g/L of sulphite and 9.38 g/L of carbonate. Unlike D-32's second ratio, this one changes nothing but the concentration - it is a dilution and not a reformulation.

Purpose

Kodak’s header is “Pyro-soda dish developer for general use with plates and films”, and the list of packed developers at the front of the handbook says the same thing in the same words. General use is what distinguishes it: this is the ordinary pyro developer of the London handbook, against D-167 on the facing page, which is the fast staining one for press work.

A pyro developer leaves a second image. Pyro’s oxidation product is yellow and is deposited in the film along with the silver, so a pyro negative carries a silver density and a colour density. The staining and tanning developers lesson sets out what that is worth and the pyrogallol page carries what the course can and cannot establish about the product. What this course cannot do it does not do here: it cannot name the yellow compound, cannot give an equation for its formation, and cannot describe how pyro tans the gelatin it develops.

And this formula is much less of a staining developer than its neighbour, because of one ingredient in Solution C. See the arithmetic below.

Recommended uses

Plates and films, generally, which is the header.

Where a pyro negative is wanted without the extremes. Twenty-five grams of sulfite per litre in the working bath puts D-177 nearer a conventional developer than a classical A.B.C. pyro is — more than twice D-1’s dose and five times D-167’s.

Portraits, at the published dilution. Kodak gives a second working strength for portraits and softer negatives, which is a use statement as well as a dilution.

Where shelf space and keeping matter. The 150 mL stock is the smallest bottle of anything in this formulary, and it is small on purpose: an agent that oxidises as readily as pyro keeps better concentrated, acid and in a bottle that is full.

As the middle term of the pyro range. D-1 at 6 g/L of pyro and 7.5 g/L of carbonate in 7 to 9 minutes; D-177 at 6.25 and 18.75 in 5 to 8; D-167 at 7.5 and 37.5 in 2 to 3. One handbook, three developers, one agent, and the alkali doing the work.

When another formula is preferable

• For a hard, fast, heavily stained negative, D-167: twice the alkali, a fifth of the preservative, Elon beside the pyro, and two to three minutes.
• For the classical stain, Kodak’s D-1, the standard A.B.C. pyro, whose working sulfite is 10.5 g/L against this formula’s 25. If the stain is the point, D-177 is the wrong end of the range.
• Where no stain at all is wanted, D-76, D-19 or D-23. A hundred grams of sulfite per litre is what a developer looks like when it is designed to hide its oxidation product.
• Where the negative must not be tanned, any non-pyro developer.
• Where a bath must last a session. Thirty minutes in a dish is the published life, and it is the shortest in the handbook.
• Where the agent is the objection. See Safety; pyro sets this page’s level.

Mixing

Three bottles, and one of them is made from another.

1. Solution A, the stock for storage. Dissolve, in this order, 1.4 g of potassium metabisulphite, then 12.5 g of pyro, then 1.7 g of potassium bromide; water to make 150 mL. Preservative first is the handbook’s rule wherever there is no Elon in the formula. Keep this bottle full, closed and dark.
2. Solution C. Dissolve 50 g of anhydrous sodium sulfite — or 100 g of the crystals, the handbook’s main column — then 37.5 g of anhydrous sodium carbonate — or 100 g of the crystals; water to make 1,000 mL.
3. Solution B, when it is wanted. Take the whole 150 mL of Solution A and make it up to 1,000 mL with water.
4. The working developer. Equal parts of B and C for negatives of average contrast; equal parts of B and C with two parts of water for portraits and softer negatives.

Why A is 150 mL and not a litre. Because the whole of it becomes a litre of B, and Kodak’s heading says the rest: stock solution for storage. A concentrated, acid, full, small bottle is the best keeping arrangement available for an agent that the 1928 primer singles out as oxidising much more readily than Elon or para-aminophenol for a given amount of preservative. The handbook’s general storage note makes the same argument for every stock: keep it in small bottles, because the air space in a large one increases each time it is opened.

🧮Three pyro developers from one handbook, at their working strengths

Because Solution A is made up to 150 mL and its whole volume becomes a litre of B, Solution B carries A’s quantities per litre exactly — 12.5 g of pyro, 1.4 g of metabisulphite, 1.7 g of bromide. Mixed one to one with C:

12.5 g/L ÷ 2 = 6.25 g per litre

Pyrogallol

50 g/L ÷ 2 = 25 g per litre

Sodium sulfite, anhydrous

37.5 g/L ÷ 2 = 18.75 g per litre

Sodium carbonate, anhydrous

1.7 g/L ÷ 2 = 0.85 g per litre

Potassium bromide

1.4 g/L ÷ 2 = 0.7 g per litre

Potassium metabisulphite

Set the three pyro developers of the corpus side by side at the strength each is used at:

Working bath	Pyro	Preservative	Carbonate	Bromide	Time at 18 °C
Kodak D-1, tray	6 g/L	10.5 g/L sulfite	7.5 g/L	0.11 g/L	7–9 min
D-177, average contrast	6.25 g/L	25 g/L sulfite + 0.7 metabisulphite	18.75 g/L	0.85 g/L	5–8 min
D-167	7.5 g/L	5 g/L metabisulphite only	37.5 g/L	none	2–3 min

The pyro is nearly constant and everything else moves. Kodak calls D-167 a staining developer and D-177 merely a pyro-soda one, and the sulfite column is why: this course’s own account of the class is that sulfite is the dial that decides whether a pyro developer stains, and D-177’s dial is turned five times further up than D-167’s and more than twice as far as D-1’s. On that reading D-177 is the least staining of the three, which is a reading of Kodak’s numbers against Kodak’s headers and not a measurement anybody has published.

The softer dilution halves all five figures: 3.13 g/L of pyro, 12.5 of sulfite, 9.38 of carbonate, 0.43 of bromide.

Behaviour

Thirty minutes in a dish. That is the published working life, and it is the shortest figure in the handbook’s whole developer table. Three hours in a covered tank. A pyro developer in an open dish is oxidising while you look at it.

One month in a full stoppered bottle, two weeks half full, “in 3 solutions”. Which three the handbook means — A, B and C, or A and C with B made as required — is not stated, and both readings fit. Either way the figure is a good deal shorter than D-167’s three months, and the reason is visible in the two stocks: D-167’s agent solution carries two thirds of a gram of preservative for every gram of pyro, and D-177’s carries about a ninth of a gram.

Twelve sheets of 8 by 10 per 160 fluid ounces in a narrow dish, twenty-four in a deep tank. The published useful life, identical to D-1’s, D-167’s and D-82’s, and the lowest pair of figures in the table. Pyro developers are not economical.

Five to eight minutes at 18 °C, published once and printed after both dilutions, so whether the diluted bath shares the time is not stated. Kodak’s own softer strength is half the concentration, and half the concentration is not usually the same time; the handbook does not say and neither does this page.

Its alkali has a reserve and its energy sits in the middle of the range. Eighteen and three-quarter grams of anhydrous carbonate per litre is two and a half times D-1’s and half D-167’s, which is where the five-to-eight minutes come from.

Image characteristics

A stained negative, but the least stained of the three. That is a reading of the sulfite loads against Kodak’s own headers, set out in the arithmetic above, and it is offered as a reading. Nothing in the source compares the three, and no measurement exists in this corpus.

A second density that behaves differently from the silver. What a stain image does on graded and variable-contrast papers, and how it reads through a densitometer’s different channels, is set out in the staining and tanning developers lesson.

Tanning, by a mechanism the course cannot describe. Pyro hardens the gelatin it develops. The pyrogallol page establishes that this happens and records that the chemistry joining that observation to the rest is not in the corpus.

Kodak’s own contrast statement is a use statement. Average contrast at one strength, portraits and softer negatives at another. No curve, no gamma, no development series.

Everything downstream matters to a stain image, and Kodak Limited prints nothing about it for this formula. The practices a modern pyro developer’s own maker publishes — a non-acid stop, a non-tanning fixer, a long wash, no hypo eliminator because the colouring intensifies during washing — are recorded on the pyrogallol page and belong to that product, not to this one.

The mechanism

One agent, reducing exposed halide and leaving a coloured product behind.

AgBr + e⁻ → Ag + Br⁻

What the pyro is doing, grain by grain

⚗Three solutions, and what each separation buys

Agent from alkali is the first separation and the classical one. The 1928 primer’s reason is specific to this agent: the reason why it is customary to keep a developer like pyro in two solutions is because pyro oxidises much more readily than Elon or para-aminophenol with a given amount of preservative. Kodak Limited says the same as a general rule - developers particularly susceptible to aerial oxidation are divided into two or three solutions with the developing agent kept separate from the alkali.

Acid preservative from neutral is the second. Solution A’s metabisulphite dissolves to hydrogen sulfite, so the agent stock is acid:

S₂O₅²⁻ + H₂O → 2 HSO₃⁻

What the metabisulphite becomes in the stock bottle

and the primer’s rule is that oxidation progresses less readily in acid than in alkaline solution. The bulk of the preservative - the 50 g/L of neutral sulfite - waits in Solution C, where it is beside the alkali and cannot protect the agent bottle and cannot suppress the stain until the moment of use.

Concentration from dilution is the third, and it is the one that needs the schema’s solution ingredient. A stock at 83 g/L of pyro in 150 mL is a smaller air space and a larger reserve of preservative per unit volume than the same pyro spread through a litre. Kodak makes the concentrate, calls it the stock for storage, and prints its dilution as a separate solution rather than as an instruction.

What the course cannot say. The identity of pyro’s yellow oxidation product, the equation for its formation, and the mechanism of its tanning action are all outside what this corpus establishes. The pyrogallol page says so in terms and this page does not go further.

Function of every ingredient

Potassium metabisulfite, 1.4 g in Solution A — 9.3 g/L of that stock, and 0.7 g/L in the working bath. The preservative of the stock bottle, and an acid one: it dissolves to hydrogen sulfite, so Solution A is an acid solution of a very readily oxidised agent, and the primer’s rule is that oxidation progresses less readily in acid than in alkali. Note how little of it there is relative to the pyro — about one part in nine by weight, against D-167’s two parts in three — and note that this is a keeping decision rather than a stain decision, because the sulfite that governs the stain arrives later, in Solution C. More of it would keep the stock longer; less would give a bottle that browns. Kodak’s own chemical notes record that metabisulphite costs two to three times sodium bisulfite for the same job and that the two are customarily substituted weight for weight.

Pyrogallol, 12.5 g in Solution A — 83 g/L of that stock, 12.5 g/L of Solution B and 6.25 g/L in the working bath. Kodak calls it pyro and defines it as 1:2:3 trihydroxybenzene. The only developing agent in the formula, and the reason for every other decision on this page. Its oxidation product is yellow and deposits in the film with the silver, so the negative gets a second density; it also tans the gelatin, by a mechanism the course cannot describe. More pyro gives more density and more stain; less gives less of both. Two practical facts from its own page matter at the bench — it turns grey on exposure to light and air, so the stock lives in a full dark bottle, and Kodak supplied the crystal rather than the powder because the powder flies about the darkroom and settles on plates and paper as spots.

Potassium bromide, 1.7 g in Solution A — 11.3 g/L of that stock, 1.7 g/L of Solution B and 0.85 g/L in the working bath. The restrainer, holding down the chemical fog that an 18.75 g/L carbonate alkali would otherwise produce. It sits in the agent stock rather than with the alkali, which is the opposite of where the primer’s own definition of a two-solution developer puts it and is possible because bromide has no action on the developing agents and may be added at any stage. More would clean the highlights and slow the bath; less would fog. Eight times D-1’s dose and, against D-167, the difference between having a restrainer and having none.

Sodium sulfite, 50 g anhydrous in Solution C — 25 g/L in the working bath, and the ingredient that decides what kind of pyro developer this is. It is the preservative proper: it takes up pyro’s oxidation product, and in doing so it takes up the stain, because the stain is the oxidation product deposited in the film. Kodak’s 1928 primer states the whole dial in one place — a pyro developer without sulphite gives a very yellow negative; add sulphite and the image is much less yellow; add a great deal and you get almost as blue an image as with Elon. At 25 g/L this formula sits well up that scale, which is consistent with Kodak calling D-167 a staining developer and calling this one merely a pyro-soda developer. More would suppress the stain further and move towards a conventional negative; less would stain harder and keep worse. The handbook prints the crystalline heptahydrate at exactly twice the weight as its own alternative.

Sodium carbonate, 37.5 g anhydrous in Solution C — 18.75 g/L in the working bath. The alkali, and a reservoir rather than a dose: a carbonate is only partly dissociated at any moment and so holds its hydroxide concentration nearly constant through a development, where a caustic alkali would present everything at once. The primer’s rule is that the quantity of alkali governs the energy of the developer, that too much gives chemical fog, and that alkali softens gelatin. At two and a half times D-1’s dose and half D-167’s, this is the middle setting, and it is where the five-to-eight minutes come from. The anhydrous salt is what the formula means and what the handbook recommends; its main column prints 100 g of the decahydrate crystals instead, and weighing crystals as though they were anhydrous would give a bath a third as alkaline as intended.

Solution A, 150 mL of it, is the whole of Solution B. That is Kodak’s own ingredient line and it is recorded as one, rather than being expanded into A’s three solids, because expanding it would replace Kodak’s arrangement with the course’s arithmetic and would lose the fact that the reader keeps one small concentrated bottle and dilutes the whole of it when a litre of working stock is wanted. Because A is made up to 150 mL, Solution B carries A’s numbers per litre unchanged — which is a tidy piece of design and is presumably why 150 mL was chosen, though the handbook does not say so.

Water, three times: to make 150 mL, to make 1,000 mL, and to make 1,000 mL again, plus the two further parts in the softer dilution. No temperature is given for any of them. The one that carries a practical warning is Solution C’s, which has to dissolve up to 200 g of crystals and is much easier warm — and must be cool before it meets the agent stock.

Interactions

With air, and this is the interaction that governs the formula. Thirty minutes in a dish, three hours in a covered tank: a factor of six for a lid.

With the size of the bottle. One month full against two weeks half full, on Kodak’s own table. The handbook’s advice to keep stock in small bottles is not general good practice here, it is this formula’s design principle written out.

With the sulfite tub’s age, in both directions: Solution A’s metabisulphite loses sulfur dioxide on standing, and Solution C’s sulfite oxidises to sulfate, which is not a preservative. A stale C stains harder than a fresh one.

With everything after the tray, if the stain is to be preserved. Kodak Limited prints nothing about stop baths, fixers or washing for this formula; the practices a modern pyro maker publishes are on the pyrogallol page and belong to that product.

With a non-hardening fixer such as F-52, if the tanning is to be judged on its own rather than added to.

With iron. Iron in a bisulfite gives a dark colour in a pyro solution, per the 1928 primer’s chemical notes. In a developer that is meant to stain, an accidental colour is the hardest fault to diagnose.

Variants

D-167, the pyro-Elon staining developer on the facing page: two solutions, Elon beside the pyro, twice the alkali, a fifth of the preservative, no bromide, and two to three minutes. The two divide Kodak Limited’s pyro offering between general work and press work.

Kodak D-1, the standard A.B.C. pyro, printed in the 1928 primer and again in this handbook: three stocks, and a working tray solution of 6 g/L of pyro, 10.5 g/L of sulfite and 7.5 g/L of carbonate, 7 to 9 minutes at 18 °C, with a tank dilution at eleven parts of water and 13 to 15 minutes. Its entry is planned and not yet written; the staining and tanning developers lesson prints its quantities. D-177 is the same idea with more sulfite, more alkali and a concentrated storage stock.

Kodak’s own softer dilution, one part B, one part C and two parts water for portraits — recorded above as a second combination rather than as a variant, because it is the maker’s own.

The crystalline sulfite and carbonate columns, which are the handbook’s main columns and are recorded in the table as alternative forms.

The packed powder. The handbook’s asterisk offers this formula as Kodak Pyro-Soda Developer Powder D-177. The course does not assume the packed product is this formula: a manufacturer’s powder is a proprietary preparation whose composition is not disclosed beyond the number on the packet, and the formulary publishes the formula the handbook prints, not the contents of the tin.

No course variant is offered. The preservative is the one thing a reader might want to change, and changing it produces one of the other two published pyro developers rather than a safer version of this one.

Safety

Level B, set by the agent.

Pyrogallol is the reason. Read its page before opening the jar. Its classification, its handling controls and Kodak’s own preference for the crystal over the powder — because the powder flies about the darkroom — are recorded there and are not summarised here. Gloves, no dust, no skin contact, and the weighing done deliberately.

Solution A is the most concentrated agent solution in this formulary, at 83 g of pyro per litre. A splash of it is not a splash of working developer. Handle the small bottle with the respect the concentration deserves.

Potassium metabisulfite gives sulfur dioxide in acid, and Solution A is acid. Weigh it in moving air, keep the tub closed, and keep every stronger acid away from the stock and its waste. Anyone with asthma should read that page first.

Sodium sulfite and sodium carbonate are the ordinary darkroom solids: gloves, eye protection, and no dust while weighing 50 g and 37.5 g of powder.

Ventilation as for any darkroom.

Storage

One month in a full stoppered bottle and two weeks half full, as the three solutions. Kodak’s own figures, and shorter than every other developer in that table except D-82’s one week and D-170’s three weeks.

Thirty minutes in a dish. Mix for the sheet, not for the session.

Solution A small, full and dark. The 150 mL is not an inconvenience, it is the formula’s keeping strategy: a concentrated acid stock in a full small bottle. Decanting it into a large bottle would undo the design. Pyro turns grey in light and air, so a stock that has darkened has already made some of its stain in the bottle rather than in the film.

Solution C is the durable one — sulfite and carbonate in water, with nothing in it that oxidises usefully — but the sulfite does slowly become sulfate, which is what a stale C would show as extra stain.

Solution B is the awkward one and the handbook does not discuss it. It is A diluted, so it has A’s preservative spread through six and a half times the volume. Whether Kodak’s “in 3 solutions” means B is among the bottles kept, or means A is kept and B made as required, is not stated. The safe reading — and it is a reading — is to make B when it is wanted.

Label all three bottles with the formula, the letter, the strength and the date, per the labelling SOP, and record the batch on the formula version record. Label Solution A as containing pyro in words someone who has not read this page would understand.

Incompatibilities

Acids, with Solution A: an acid metabisulphite stock plus a stronger acid gives sulfur dioxide.

Oxidising agents of every kind. Pyro is the most readily oxidised agent in this course.

Iron, from a tray, a clip or a contaminated tub, which darkens a pyro solution.

Fixer, in either direction — one pair of tongs per tray, and the more so with a bath that stains.

Light and air, for Solution A, which is a storage matter and a practical incompatibility both.

Anything the incompatibilities page lists against a reducing agent or an alkali, which is the page to read rather than this paragraph.

Waste

Developer waste, alkaline, carrying pyro and its oxidation products, sulfite, carbonate and bromide. Not the silver stream — that is the fixer’s.

Keep it out of the acid stream, both because developer and fixer wastes are collected separately and because the metabisulphite in it gives sulfur dioxide with acid.

Pyro is the constituent that makes this more than soapy water. Collect it, label it, and follow the general chemical waste SOP and the disposal ruling. Local regulation decides, and this course cannot tell you what it says where you are.

Troubleshooting

Solution A has gone grey or brown. Pyro oxidising in the bottle. Check that it is full, closed and dark, and check the age of the metabisulphite; a stock that has darkened has spent some of its stain already.

The working bath went dark in the dish. Expected past about half an hour, which is Kodak’s own dish figure. Mix for the sheet.

The negative is thin, or has no stain worth measuring. An oxidised Solution A develops less and stains in the bottle rather than in the film. Alternatively Solution C is stale: sulfite that has become sulfate does not preserve, but neither does it suppress the stain, so a stale C usually shows as more stain and not less.

Fog, or a veil across the frame. Check the carbonate arithmetic first — anhydrous weighed as though it were crystals gives a bath nearly three times as alkaline as intended — and then the bromide, which lives in Solution A and is easy to leave out of a small stock.

The negative is too contrasty. Kodak’s own remedy is its second dilution: equal parts B and C with two parts of water, which it publishes for portraits and softer negatives.

Yellow-brown spots unrelated to the image. Pyro dust, which is why Kodak supplied the crystal rather than the powder.

The negative is unusually hard to fix, or dries oddly. Pyro tans the gelatin it develops, and this is a property of the class rather than a fault of the batch.

A sharp smell from Solution A. Sulfur dioxide, which means something acid has reached it or the metabisulphite is decomposing. Ventilate first.

Experiments

Measure the stain, and the sulfite that governs it. Develop step wedges in D-177, in D-167 and in D-1, and read each visually and through a blue filter. The difference between the two readings is the stain. This course’s claim — that D-177 is the least staining of the three because it carries the most sulfite — is a reading of Kodak’s numbers and has never been tested.

Test whether the published time covers the diluted bath. Kodak prints one time after two dilutions. Develop identical strips at both strengths for 5 to 8 minutes and see whether either lands anywhere near the other. If they do not, the handbook has an omission and this page has correctly refused to guess at it.

Find out what the small bottle is worth. Make Solution A in a full 150 mL bottle and in a half-empty 500 mL one, and develop identical strips from each at a week, a month and three months. Kodak’s table gives one month full and two weeks half full for the set of three; nobody has isolated A.

Ask what “in 3 solutions” means. Keep one set as A and C, making B when wanted, and another as A, B and C all bottled, and test both at a month. The handbook does not say which arrangement its figure describes; this settles it for your own conditions.

Take the alkali series. Kodak’s three pyro developers carry 7.5, 18.75 and 37.5 g/L of anhydrous carbonate in the tray and develop in 7 to 9, 5 to 8 and 2 to 3 minutes. Plot time against alkali on one film. Three points on one graph, from one handbook, and the handbook draws no graph.