KODAK PROFESSIONAL XTOL Developer

Sixteen pages. Kodak Alaris publishes a specific gravity to three decimal places with a tolerance and a measuring temperature; a pH to two decimal places with a tolerance; four make-up volumes; five storage conditions; a capacity with a compounding time-compensation ladder; a replenishment rate adjustable in ten-millilitre steps; three different seasoning agents with catalogue numbers; two agitation regimes written out step by step; and eight tables of development times spanning five temperatures, two dilutions, four kinds of processing and films from three manufacturers.

Of what is actually in the two packets it publishes two phrases, both in the features column of the table on page one: “Ascorbic acid-based black-and-white film developer” and “No hydroquinone”. One names a class of substance and the other names a substance that is absent. There is no third phrase, no quantity of anything, no safety data sheet that can be cited, and no patent. This page is what that leaves, which turns out to be a great deal.

Kodak Alaris Inc. — sold as two part powder

Not disclosed. Kodak publishes no composition for XTOL and no quantity of any substance. The whole of what sixteen pages say about what is in the two packets is two entries in a features column - "Ascorbic acid-based black-and-white film developer" and "No hydroquinone" - one of which names a class of substance and the other of which names a substance that is absent. No agent quantity, no second developing agent, no alkali, no preservative, no restrainer, no antifoggant, no sequestrant, no ratio between the two packets and no formulation date appears in any Kodak document this course holds. Nor is there a hazard document to read instead: Kodak Alaris serves its safety data sheets only through a session-bound portal that cannot be cited or recorded, no sheet for Part A or Part B could be obtained, and this page therefore discloses no components at all rather than borrowing a composition from another maker's ascorbate product, from a patent, or from the encyclopaedia entry for the pure acid. A reader who wants to know why this developer behaves as it does at pH 8.2, or to move one term and watch what happens, must mix an open formula instead of buying this one - and a reader about to open the packets should get the current safety data sheet from the seller first.

Nearest open formula. Kodak D-76 — Kodak's own documents make the choice for you by printing the two developers in adjacent columns of the same tables for the same films at the same temperatures, so the comparison is the maker's and not this course's. Both are general-purpose black-and-white film developers mixed from powder by the same company, used at full strength in a tank, a tray or a rotary tube or diluted 1:1 for one-shot work, reused with a published time compensation or replenished. D-76 is four weighed chemicals whose functions can each be named, moved one at a time and watched; XTOL arrives as two sealed packets described by two phrases. Against that, XTOL wins on nearly everything Kodak publishes: 5 rolls per litre against D-76's 4 and two months' tank life against one, in one table of one document; its own solution as its replenisher, where D-76 needs D-76R, a different formula with 1.5 times the agents and ten times the borax; and a published pH and specific gravity, which D-76's own technical sheet does not print at all. Where the comparison is weak is exactly where a reader most wants it - chemistry. D-76 is metol, hydroquinone, sulfite and borax. XTOL is "ascorbic acid-based" with "no hydroquinone". On the published evidence the two share not one named ingredient, so this is a comparison of use, cost and behaviour and not of composition, and no open ascorbate film developer exists in this formulary to make the closer comparison with.

⚠There is no safety data sheet on this page, and that is a finding rather than an omission

Every other bought-product page in this formulary carries a table of components read off the maker’s own safety data sheet. This one carries none, and the reason matters more than the gap.

Kodak Alaris no longer publishes its safety data sheets at any address that can be cited. Its own corporate Environment, Health and Safety page, the page a reader is sent to, holds no sheets at all. Under the heading “Safety Data Sheet and regulatory shipping data for chemical products” it prints one line — “New Link: Safety Data Sheets (remember to update your bookmarks!)” — and then four numbered steps instructing you to save a bookmark and paste in a session-token URL on a third-party portal. A session token is not a document. It cannot be recorded as a source, it will not resolve for the next reader, and this course’s citation rules exist precisely so that it is not pretended otherwise.

So this page does not know what is in the packets, and it does not guess. It will not borrow a composition from another maker’s ascorbate developer, from a patent that does not name this product, or from the encyclopaedia entry for pure ascorbic acid — each of which would be a different substance in a different mixture at an unknown concentration.

What you should do before you open the carton. Ask the seller for the current safety data sheets for Part A and Part B, read them, and record them: the SOP for recording a safety data sheet is one page long and exists for this. Part II’s lesson on reading an SDS is where the sections and the GHS codes are explained. Until you have that sheet you are handling two bags of unidentified powder, and this page treats you as if you are, which is why it is classified Level B rather than Level A.

Purpose

To develop a black-and-white negative — Kodak’s own films and other manufacturers’ — at what Kodak calls full emulsion speed, using one solution that is also its own replenisher, in anything from an eight-ounce tank to a high-volume processor.

Kodak’s own opening sentence: XTOL “is a two-part powder developer for processing KODAK and other manufacturers’ normally exposed, pushed, or pulled black-and-white films. It offers full emulsion speed and easy mixing, and can be used as both a developer and a replenisher in a variety of equipment, from small tanks (8 to 64 fluidounces), trays, or rotary tubes to high-volume processors.”

Three of those clauses are doing real work and are worth separating before anything else.

“Two-part powder” is a manufacturing decision with a photographic consequence. Two packets exist because something in the developer will not sit next to something else in a sealed bag, and the mixing instruction shows you the moment they meet: Part A goes in first and turns the water tawny or copper-coloured, and Part B clears it. What causes either the colour or its clearing is not published and this page does not invent it, but the sequence is not arbitrary and the instruction is not a suggestion.

“Both a developer and a replenisher” is unusual and is the claim with the most practical weight on the whole sheet. The comparison is with Kodak’s own D-76, which is replenished with D-76R — a different formula, carrying one and a half times the metol and hydroquinone and ten times the borax, because a working tank loses alkali reserve faster than it loses agent. XTOL replaces that with one powder and one instruction: 70 mL of the same solution per roll. That is a simplification a home darkroom will never use and a working lab will feel every week.

“Ascorbic acid-based”, with “No hydroquinone” printed beside it as a benefit, is the only compositional statement in the document, and the fact that an absence is advertised is the story of the last thirty years of developer chemistry compressed into three words. Part VIII’s lesson on the alternative developing agents sets out what an ascorbate is and why a maker would want one; the short version is that vitamin C reduces exposed silver halide well enough to replace the agent photography had used since 1880, and that the substituted benzene ring photography had used since 1880 is a suspected carcinogen and mutagen.

Recommended uses

Full strength, in a small tank, for a roll of film. This is the default and the strength every other figure on the sheet is written for: the capacity, the reuse ladder, the replenishment rate, the seasoning dose and the storage lives all assume it. Kodak’s small-tank range is 8 to 64 fluidounces, which covers every daylight tank a home darkroom owns.

Full strength, in a tray or a rotary tube, for sheet film. Tables 5 and 6 exist for this, and the tray instruction begins with a presoak — Kodak’s stated reason being that presoaking gives more even development, and that even a single sheet should be presoaked so that its rate of development matches that of sheets processed in a stack.

Diluted 1:1, once, and thrown away. For slightly greater film speed, enhanced sharpness and shadow detail, and slightly more grain. There is a floor on the volume and it is not negotiable — see What the maker publishes — and there is no dilution beyond this one that Kodak recommends for any film.

Push processing, indexed by contrast rather than by speed. Every row of every table names an exposure index and a Contrast Index, and the published rows run to EI 3200 for TRI-X 400 and to EI 25000 for T-MAX P3200 in a small tank. That structure is the reason to reach for this sheet rather than a rule of thumb: you are not choosing “two stops push”, you are choosing a contrast aim and reading the time that Kodak’s testing puts against it. Part XIII’s lesson on gamma, contrast index and average gradient is what makes that column mean something.

A replenished tank line. One solution for developer and replenisher, 70 mL per roll, adjusted in 10 mL steps against control strips, with seasoned tables of its own. This is the use the product was designed around and the one a home darkroom will never exercise; it is included here because it explains half the sheet.

Films this course has pages for. Kodak publishes XTOL times not only for its own emulsions but for Fuji’s Neopan 400 and 1600 and for ILFORD’s Pan F Plus, FP-4 Plus, HP-5 Plus, Delta 100 and Delta 400. A maker publishing development times for a competitor’s film is rare enough to notice, and it makes the sheet a genuinely general reference rather than a captive one.

When another formula is preferable

When you want to learn what a developer is. This is the first and largest reason and it is not a criticism of the product. A formula you can weigh out is a formula you can take apart: D-76 is four chemicals whose functions can each be named, and D-23 is two, which is why Part VIII’s mixing lesson uses them. XTOL is two sealed packets and two phrases. You can use it superbly and learn nothing from it.

When you want to move one term and watch what happens. The whole of Part IX, the developer laboratory, is built on changing one meaningful variable at a time. You cannot change the sulfite in XTOL, or its alkali, or its restrainer, because you do not know that it has any of them. The only variables Kodak leaves you are dilution, time, temperature, agitation and seasoning — which is a real experimental space, and a much smaller one than an open formula gives.

When you cannot get the safety data sheet. This is a practical argument and it is specific to this product in this year. With an open formula you know every substance you are handling, you can look each one up in the chemical encyclopaedia, and you can make a hazard assessment that is yours. With XTOL, unless the seller supplies current sheets, you cannot.

When you want a stain, or a tanning developer, or a compensating one. XTOL is a general-purpose developer that claims, in Kodak’s own words, printing characteristics like those of other general-purpose developers. If you want an image whose silver sits inside a proportional dye stain, the formulary’s staining developers — 510-Pyro among them — do something this cannot, and Part VIII’s staining lesson explains why.

When your water is hard. Kodak’s own warning: above 200 ppm of calcium carbonate you may need conditioned water to avoid cloudiness when mixing higher dilutions, and it tells you to contact your water authority. An open formula lets you deal with hardness by choosing the water; here the maker simply names the threshold.

When one litre is what you want. The sizes table lists packs to make 1, 5 and 50 litres. The mixing table tells you how much water to start with for 2, 5, 25 and 50 litres. Those two tables, on the same page of the same document, do not line up: there is no water figure for the one-litre pack and no pack for the 2-litre or 25-litre rows. Kodak notes that sizes and catalogue numbers may differ from country to country, which explains the mismatch without removing it. It is not the only place where the sheet’s prose and the sheet’s table disagree; see What the maker publishes.

What the maker publishes

Mixing

Five steps, and every one of them carries information.

1. Start with water at about 75 per cent of the final volume, at ordinary room temperature — Kodak gives 65 to 85 °F (18 to 30 °C). No warming, no hot dissolve, no order-of-magnitude tolerance on the temperature: this is a developer designed to be made up in a bucket in a room.
2. With stirring, add Part A slowly and stir until it is completely dissolved. At this point “the solution may appear somewhat tawny or copper-colored. This is normal.”
3. Continue stirring and add Part B slowly, again until completely dissolved. “The coppery tint will clear from the solution as you add Part B.”
4. Add water to bring the final solution to 2, 5, 25, or 50 litres.
5. Stir until the solution is uniform.

The make-up-to-volume ending in step 4 is the point of the whole sequence and is worth naming, because it is the difference between a solution and a mixture: the developer is a strength, not a set of masses in a heap of water, and Kodak specifies it by a property of the finished litre. Part II’s dilution lesson is where that distinction is worked out, and the SOP for mixing to a final volume is how it is done at a bench.

✕Seventy-five per cent, or eighty? The sheet says both

Step 1 says to start with water at approximately 75 percent of the total volume and refers you to the table. Every row of that table is 80 per cent: 1.6 litres for 2, 4 for 5, 20 for 25, 40 for 50.

The discrepancy does not matter in use, because step 4 makes the solution up to its final volume and the starting figure only has to leave room for the powders and for stirring. But it is worth naming in a document being trusted for a pH to two decimal places and a specific gravity to three, and it is a small standing lesson in reading manufacturer literature: the table is the instruction, the prose is the summary, and where they differ the table is what was tested.

There is a second mismatch on the same page. The sizes table lists packs to make 1, 5 and 50 litres; the water table gives figures for 2, 5, 25 and 50 litres. Kodak’s own note that sizes and catalogue numbers may differ from country to country accounts for it, but a reader with a one-litre pack is left to take 80 per cent themselves.

The specification you can check

If correctly mixed, the specific gravity of the working tank solution is 1.085 ± 0.003 measured at 77 ± 0.5 °F (25 ± 0.3 °C) at pH 8.2 ± 0.05.

Read that sentence again for what kind of sentence it is. It is not a description of the product; it is an acceptance test, and the conditional at the front — if correctly mixed — says so. Kodak is telling you how to find out whether the thing in your tank is the thing on the packet, using two instruments a serious darkroom already owns.

That is rare. ILFORD publishes pH and specific gravity for its powder developers in the same spirit. Kodak’s own D-76 sheet, publication J-78, publishes neither: search it for a pH and there is none. A reader who mixes D-76 from the packet has no maker’s figure to check the result against; a reader who mixes XTOL has two, with tolerances and a measuring temperature.

Both figures are for the working tank solution at full strength. Neither is published for the 1:1 dilution, and neither is published for either packet on its own.

⚗Why the specific gravity is not a back door into the formula

A specific gravity of 1.085 means the solution is 8.5 per cent denser than water at the same temperature. It is extremely tempting to turn that into a total dissolved-solids figure and then to start apportioning it between an ascorbate and a bulk salt. Do not, and this page does not.

The reason is not caution for its own sake. Converting a density into a mass of solids requires knowing the partial molar volumes of the substances dissolved — how much each one expands the solution it is in — and those differ substantially from one salt to another. The conversion therefore needs the answer to the question it is being used to ask. Any number you get out of it is a number about an assumed composition, not a measurement of the real one, and printing it would be exactly the failure this page kind exists to prevent: an inference with a citation attached.

What the figure is good for is what Kodak says it is good for. It is a repeatable property of a correctly made batch, so it detects a mis-measured make-up volume, a partly dissolved powder, or a packet mixed into the wrong quantity of water — and it does that without knowing what is dissolved at all. That is the honest use of it, and it is a genuinely useful one.

Storage of the mixed developer

Condition	Published life
Full, tightly closed container	6 months
Partially filled, tightly closed container	At least 2 months
Replenisher tank with a floating lid	Indefinitely, if new solution is added to replace that used by the processor

Kodak’s instruction and its reason are printed together: store in full, tightly closed containers or in a replenisher tank with a floating lid, minimise the air space in the storage container, because “partially filled containers allow oxidation of the solution”.

Two of those three entries are not the figures they look like. “At least 2 months” is a floor, not a life — Kodak declines to say what a half-empty bottle actually does after that. “Indefinitely” is conditional on continuous replacement, which makes it a statement about a replenished process rather than about a bottle on a shelf: a tank that is being topped up is not the same liquid six months later.

The chemicals comparison sheet adds the figure J-109 leaves out, the one that matters to anyone using a tray: 24 hours for the working solution in a tray, against 2 months in a tank. The same table gives D-76 one month in a tank.

And a real absence. J-109 publishes no shelf life for the powders. Not for a sealed packet, not for an opened one, and there is no instruction about what to do with a part-used packet. ILFORD, on the comparable product, says to prepare the stock solution immediately once the packets are opened. Kodak says nothing, and this page will not supply the sentence.

Capacity, and the ladder it depends on

At full strength, unreplenished, the capacity is approximately 15 rolls of 135-36 or 120 film per litre — or the equivalent of 80 square inches (516 cm²) — with time compensation, after which Kodak says to discard the developer.

The compensation is a three-rung ladder, per litre:

Rolls processed	Development time
1 to 5	Normal development time
6 to 10	Normal development time increased by 15 per cent
11 to 15	The adjusted development time increased by a further 15 per cent

The word adjusted on the third rung is doing arithmetic. The second increase is applied to the already increased time, so 1.15 × 1.15 = 1.3225: rolls 11 to 15 run at about 132 per cent of normal, not 130. That compounding is Kodak’s own wording read literally, and the arithmetic is this course’s.

Kodak’s area equivalence is worth memorising because every capacity and replenishment figure on the sheet is written in it: 80 square inches is one 135-36 roll, one 120 roll, four 4 × 5-inch sheets, or one 8 × 10-inch sheet. A 220 roll is 160 square inches and counts twice.

🧮Fifteen rolls per litre, or five? Two Kodak documents, one reconciliation

J-109 says approximately 15 rolls per litre with time compensation. Kodak’s own chemicals comparison sheet, E103CF, gives XTOL a useful capacity of 19 8 × 10-inch sheets per gallon, 5 per litre — in a tray and in a tank alike. Since an 8 × 10 sheet and a 135-36 roll are both 80 square inches on Kodak’s own equivalence, those two figures are in the same units, and they differ by a factor of three.

The reconciliation is sitting in the compensation table, and it fits exactly. The first rung is “1 to 5 — use normal development time”. Five is precisely the point at which the developer stops being usable without changing anything. So E103CF’s 5 per litre reads naturally as the capacity at a fixed development time, and J-109’s 15 as the capacity if you are willing to keep lengthening it.

This is the course’s reading and Kodak nowhere states it. It is offered because the numbers fit to the roll and because the alternative — two Kodak Alaris documents contradicting each other threefold on the same product — is less likely. It is flagged here as interpretation under Rule 7, and a reader who wants certainty should test it: the experiment is in Experiments below.

The same table gives D-76 16 per gallon, 4 per litre, so on Kodak’s own comparison XTOL does 25 per cent more work per litre than the developer it is printed beside.

Dilution, and the floor underneath it

XTOL may be diluted 1:1 with water, which Kodak glosses in the same sentence as (developer:water) — one part of the made-up developer to one part of water, what ILFORD would write 1+1. That gloss matters, because a colon is ambiguous in general use; Kodak’s own HC-110 sheet fixes the convention with volumes, labelling 75 mL of stock plus 225 mL of water as 1:3.

Diluted, Kodak claims slightly greater film speed, enhanced sharpness and shadow detail, and slightly more grain. Use it once. Do not reuse it. Do not replenish it. Mix it immediately before use.

And then the instruction that is quantitative, easy to miss, and the one that actually ruins negatives:

We recommend always starting with at least 100 mL (3.5 fluidounces) of full-strength developer to prepare the diluted solution for each 135-36 or 120 roll (or the equivalent of 80 square inches).

with the reason stated: “the minimum amount of diluted developer needed to cover the film may not contain enough active ingredients to develop the film fully in the recommended time.” Kodak’s worked example is four rolls at 1:1 taking at least 800 mL of full-strength developer even if the equipment would allow less.

🧮What the 100 mL floor does to a real tank, and what it costs per litre

A single 135 reel in a 300 mL daylight tank. At 1:1 that is 150 mL of full-strength developer, which clears the floor comfortably.

Two reels in a 500 mL tank. 250 mL of developer for two rolls, or 125 mL each. Still clear.

Two reels in a 450 mL tank. 225 mL for two rolls, 112.5 mL each — clear, but the margin is now thinner than the difference between tank makers’ nominal capacities, so measure yours rather than trusting the label.

Three 120 rolls in a 1 litre tank at 1:1. 500 mL of developer for three rolls, 167 mL each. Clear.

The cost per litre. One litre of full-strength developer, reused with the compensation ladder, does 15 rolls. One litre used to make 1:1 one-shot at the 100 mL floor does ten. So the sharpness and shadow detail of the dilute bath are bought with a third of the developer’s capacity, before the longer times are counted. That arithmetic is this course’s, on Kodak’s two published figures.

The film sheets add Kodak’s limit on going further: it does not recommend more dilute solutions than its tables give, and states that dilute developers require longer development times and give slightly higher film speed and a slight increase in graininess. Whatever a forum says about 1:2 or 1:3, no Kodak document in this corpus publishes a time for one.

Replenishment and seasoning

Replenishment applies to full-strength systems only. The rate is 70 mL of XTOL Developer itself for each 135-36 or 120 roll or equivalent 80 square inches processed. Kodak’s tuning instruction is specific: monitor with black-and-white film process control strips, adjust the rate up or down in 10 mL increments, allow the process to stabilise between adjustments, and use the lowest rate that maintains control. The T-MAX 100 film sheet prints the same 70 mL independently.

Seasoning is the other half of the same idea, and it is the part that surprises people. A fresh tank is too active: Kodak says that if you choose not to preseason, initial development times will be about 10 per cent shorter than the tables, approaching the table times as the tank reaches a steady state. The tables are written for a bath that has already been used.

You season it either by taking solution from the overflow line or working tank of an in-control replenished process, or by adding one of three starters per litre:

Starter	Dose per litre
KODAK Developer Starting Solution (CAT 146 6382)	6.5 mL
KODAK EKTACHROME R-3 First Developer II Starter	1 mL
KODAK PROFESSIONAL First Developer Starter, Process E-6	1.2 mL

Kodak does not say what a starter contains or what it does. Part VIII’s lesson on restrainers and antifoggants is where the general phenomenon is taught — a used bath is restrained by what development has released into it, and the 1928 primer’s account is that the accumulated restraint acts like cutting down the exposure — and it is also where the course records that fresh restrainer and accumulated restraint are not the same thing. That the XTOL starters work by that route is the course’s inference from the behaviour Kodak describes, not a statement Kodak makes, and no composition of any starter appears in this corpus.

Agitation, written out

The times mean nothing without the agitation they were determined with, and Kodak writes both regimes out in full.

Rolls in a small tank. Fill the empty tank with developer. Start the timer, and in the dark lower the loaded reel in. Attach the lid. Tap the bottom of the tank against the bench from about 1 inch (2.5 cm) to dislodge air bubbles, which otherwise interfere with development and leave low-density circles. Give up to 5 agitation cycles — 5 to 7 cycles in 5 seconds for T-MAX films — where a cycle is one full inversion and return for an invertible tank, or a 10-inch (25.4 cm) slide back and forth for one that is not. Those steps take about 7 to 20 seconds. Let the tank stand for the remainder of the first 30 seconds. Thereafter agitate for 5 seconds at 30-second intervals, 2 to 5 cycles depending on the contrast wanted and the tank.

Sheets in a tray. Presoak in water at the developer’s temperature. Slip the sheet in, rock immediately to cover it, then agitate continuously in a cycle of about 8 seconds: raise the left side about ¾ inch (2 cm) and lower it smoothly, then the near side, then the right, then the near side again. For two to six sheets, interleave from the bottom of the stack to the top continuously, rotating the first sheet 180° so its notch identifies it, and use one hand for lifting out of the developer and the other for placing into the stop bath so the developer is not contaminated.

Large tanks. This is where the tables diverge and the reason is printed: Tables 3 and 7, the seasoned tables, are based on a nitrogen-burst cycle of two seconds at 10-second intervals; Tables 4 and 8, the fresh tables, on manual agitation at 1-minute intervals. Kodak adds the general rule — significantly more agitation may require slightly shorter times, less agitation longer ones.

The eight tables, and how to read them

Table	Covers
1	Roll film in small tanks
2	Roll film in rotary tubes
3	Roll film in large tanks, seasoned (replenished) developer
4	Roll film in large tanks, fresh developer
5	Sheet film in trays
6	Sheet film in rotary tubes
7	Sheet film in large tanks, seasoned (replenished) developer
8	Sheet film in large tanks, fresh developer

Four things govern how they are read.

Every row is indexed by a Contrast Index, not by a speed. The EI column tells you what the film was metered at; the CI column tells you what the negative is aimed at. The TRI-X film sheet states the convention outright: its starting-point recommendations are intended to produce a contrast index of 0.56. So a “push” in these tables is a move up the CI ladder as much as a move up the EI ladder, and the two move together by design.

The ladders differ between Kodak’s films and other people’s. Kodak’s own emulsions are given 0.52 / 0.56 / 0.62 / 0.72 / 0.82; Fuji’s and ILFORD’s are given 0.52 / 0.58 / 0.65 / 0.75 / 0.85. The sheet does not explain why, and this page does not guess.

Bold face marks the nominal film speeds, which Kodak states in the preamble to the tables.

There are two different minimum times and a refusal. Table 1 warns that development times shorter than 5 minutes may produce unsatisfactory uniformity; Tables 2 to 8 put the threshold at 4 minutes. NR means not recommended, as determined by testing — a tested refusal, not a blank. Kodak nevertheless prints times below its own thresholds: TRI-X 400 at EI 400 in a small tank at 24 °C is 4¾ minutes, under Table 1’s own 5-minute warning. The warning and the row coexist, and the reader is expected to weigh them.

Final steps, and process control

Kodak’s own sequence after development: stop bath 30 seconds with continuous agitation; fixer for twice the time the film takes to clear, agitating continuously for the first 30 seconds and 5 seconds at 30-second intervals thereafter; a 30-second running rinse; 1 to 2 minutes in hypo clearing agent; a 5-minute wash, or ten fill-and-dump cycles in a small tank; 30 seconds to 1 minute in PHOTO-FLO solution; then dry in a dust-free place. The course’s own version of that sequence, with its reasons, is the film-processing SOP, and the stop bath the formulary teaches is SB-1.

Changing over from another developer has its own instruction and it is a good piece of process discipline: run control strips through your existing in-control process at each standard time, record the Contrast Index of each, drain and clean the tank, mix XTOL, then run more strips and adjust time or temperature until the new process matches the old Contrast Indices. Kodak refers the reader to publication Z-133E for the method; the course’s version is the SOP for control-strip processing and charting. Notice what is being matched: not the time, and not the speed, but the contrast.

What is not disclosed

The formula, and not one quantity of anything. Sixteen pages contain no mass, no concentration, no percentage and no ratio for any substance in either packet.

What “ascorbic acid-based” actually commits Kodak to, which is very little. It names a class. It does not say whether the packet holds the free acid or one of its salts — and that is not a quibble, because ascorbic acid is an acid with a pKa₁ of 4.04 and would consume the alkali of a bath specified at pH 8.2, which is exactly why sodium ascorbate exists as a photographic chemical. It does not say how much. It does not say whether the ascorbate is the only reducing agent.

The second developing agent, if there is one. Kodak names none. Part VIII’s superadditivity lesson reads XTOL as an ascorbate paired with an undisclosed agent, by analogy with the phenidone–ascorbate and dimezone-s–hydroquinone products whose makers do name a pairing — and it says plainly that this is a reading. Kodak states no such thing, and neither does this page. What can be said is what the sheet says: one agent class is named, and one substance is excluded.

The alkali. A pH of 8.20 ± 0.05 is published; what holds it there is not. A tolerance of ±0.05 pH unit across four make-up volumes and a six-month shelf life implies a buffer of some kind — that inference is this course’s, and it names no substance, because the field of candidates at that pH is wide and Kodak has narrowed it not at all.

The preservative. Every general-purpose film developer in this formulary carries sulfite, often as its largest single ingredient. Kodak does not say that XTOL contains any.

The restrainer or antifoggant. None is named — and yet the sheet’s own seasoning instruction says a fresh tank develops about 10 per cent faster than a seasoned one, which is the behaviour of a bath being restrained by something. Whether that something is put in at the factory or arrives from the film is not published.

A sequestrant. CAMEO records that the air oxidation of aqueous ascorbate is accelerated by iron and copper. A manufacturer whose headline claim is “high resistance to breakdown from oxidation” has an obvious motive to include a chelating agent. Kodak names none, and this page names none.

Which packet holds what, and in what proportion. Part A goes in first and turns the solution tawny; Part B goes in second and clears it. That is the entire published relationship between the two packets. No mass, no volume, no ratio.

And the document that would have narrowed all of this: the safety data sheet. See Disclosed components below. It is the reason this page’s component table is empty rather than short.

!What two feature bullets license, and what they do not

It is worth being exact about how much work “Ascorbic acid-based” and “No hydroquinone” can be made to do, because they are all there is.

They license this. Calling XTOL an ascorbate developer. Reading its published pH of 8.2 in the light of what an ascorbate is — a reducing agent whose driving force is strongly pH-dependent. Reading its storage rules in the light of what ascorbate solutions do in a half-empty bottle. Reading “no hydroquinone” as a real and checkable difference in what you are handling, because hydroquinone is a named substance with a GHS classification and its absence removes that classification from the packet. Linking, from here, to the chemistry the course does teach.

They do not license this. Naming a quantity. Naming a second agent. Naming an alkali, a preservative, a restrainer or a sequestrant. Deciding whether the acid or a salt is present. Deriving a total solids figure from the specific gravity. Reconstructing the formula from an ascorbate developer published by somebody else. Or concluding that anything not named is absent — a features table is advertising, not an inventory, and a safety data sheet, when one exists, is a hazard classification and not an inventory either.

And a negative disclosure is still a disclosure. “No hydroquinone” is the single most useful compositional fact on the sheet, because it is the only one that changes a risk assessment. Compare the sibling product in this library: ILFORD’s MICROPHEN declares hydroquinone at 50–70 per cent of its part A, carrying H341 (suspected of causing genetic defects) and H351 (suspected of causing cancer). Whatever else is in the XTOL packets, that substance is not, and Kodak has said so in print.

⁇No patent names XTOL, and why that matters here

The usual last resort when a manufacturer publishes no formula is the patent literature, which is Tier 1 under this course’s source standard and which has supplied real formulations elsewhere in this formulary.

It supplies nothing here. This course searched for a patent naming XTOL and found none; a full-text search returns X-tolerant scan-test logic and tall-oil chemistry, neither of which is a photographic developer. The formulary register records that finding, and records that it is the reason this entry was reclassified from a formula to a product on 6 September 2026.

The temptation the search was run to defeat. Kodak holds ascorbate-developer patents that are not about XTOL. Taking a worked example from one of those and printing it here as this product’s composition would be an inference with a citation attached — it would look exactly like sourced chemistry and would be a fabrication. Rule 1 forbids it and Rule 7 requires that the distinction be visible, so it is stated here rather than left implicit.

What would change this page. A current safety data sheet for Part A or Part B obtained from Kodak Alaris or from a seller; a Kodak patent that names the product; or a Kodak publication that gives a quantity. Any of the three would move material out of this section and into the one below it.

Disclosed components

None. This is the only product page in the formulary whose component table is empty, and the section that would normally explain the components has to explain the emptiness instead.

Why there is nothing here

A product page’s components come from one place: the maker’s own safety data sheet, read as the hazard document it is. Kodak Alaris does produce those documents — this course holds one, the eleven-page sheet for KODAK Rapid Selenium Toner, and it is a perfectly ordinary GHS sheet with a section 3 composition table carrying a Weight percent column, CAS numbers against each component, and a section 16 line naming water as an additional component. Had the equivalent sheets for XTOL Part A and Part B been obtainable, this section would be reading them.

They were not. Kodak Alaris serves its safety data sheets only through a session-bound third-party portal, and its own corporate page has been reduced to four numbered steps for bookmarking a session-token URL. That URL is not a document: it will not resolve for the next reader, it carries no version or revision date that can be recorded, and under this course’s citation architecture it cannot be cited at all. The one Kodak Alaris sheet in this corpus reached it only because a dealer mirrored the maker’s own PDF.

What this page refuses to do about it

Four substitutions were available and all four are refused, for the same reason in four disguises.

Not another maker’s ascorbate sheet. Foma’s FOMATOL P is a phenidone–isoascorbate paper developer, and isoascorbate is a different stereoisomer with a different CAS number, in a different product, at concentrations that have nothing to do with this one.

Not a patent. No patent names XTOL, and one that does not name it is evidence about something else.

Not the encyclopaedia entry for the pure substance. The ascorbic acid page carries a full hazard block, and every word of it is about the pure substance. A concentration band in a mixture is not the same object, which is why safety data sheets exist as a separate document type at all.

Not arithmetic on the specific gravity. Set out under What the maker publishes above, and refused there.

What can honestly be said about the one class Kodak names

The chemistry belongs on the ascorbic acid page and is summarised in The mechanism below. Two things belong here, because they bear directly on what a reader is handling.

The pure substance is unclassified, and that is not a statement that the packet is safe. PubChem’s aggregation of the ECHA Classification and Labelling Inventory gives ascorbic acid no signal word, no pictogram and no hazard statement: 572 of 588 reports, 97.3 per cent, say it does not meet GHS criteria. That is a fact about ascorbic acid. It is not a fact about a mixture whose other components are unknown, and HSE’s own introduction to EH40 makes the general point that a substance’s absence from the list of workplace exposure limits does not indicate that it is safe.

The absence Kodak declares is worth more here than usual. In a formulary where the classical film developers are built on metol and hydroquinone — the two substances that gave darkroom dermatitis its name and carry the suspected-carcinogen and suspected-mutagen classifications between them — a manufacturer stating in print that its product contains no hydroquinone has told you something that matters, even though it has told you nothing about what it does contain.

What is in the table and what is not

Nothing is in the table. That is not a formatting accident and it should not read as one: it is the honest output of a page that could not obtain the document its component list is made from, written out so that a reader knows the boundary rather than inferring it from a silence.

Behaviour

Temperature, and how steeply the times move

Kodak’s roll-film small-tank table runs from 65 to 80 °F (18 to 27 °C), and the mixing water is specified at 65 to 85 °F (18 to 30 °C). The claim on page one is “stable performance across a range of temperatures, dilutions, and agitation methods”, which is a claim about the shape of the response rather than its flatness — the times move a great deal.

TRI-X 400 at EI 400, full strength, small tank, to CI 0.56:

Temperature	Time
18 °C (65 °F)	8 minutes
20 °C (68 °F)	7 minutes
21 °C (70 °F)	6¼ minutes
24 °C (75 °F)	4¾ minutes

From 20 to 24 °C the time falls by 32 per cent, which is why a thermometer is not optional and why Part VIII’s kinetics lesson spends as long on temperature as it does. Note also where that last row lands: below Table 1’s own 5-minute uniformity warning. Kodak prints the row and the warning on the same page and leaves the reader to weigh them; the practical answer is that a 4¾-minute development in a hand-inverted tank is where mottled development and surge marks come from.

Reuse without replenishment, and what the ladder really costs

The compensation ladder is not a fudge factor; it is Kodak’s measurement of how fast this developer is being used up. Rolls 1 to 5 need nothing, rolls 6 to 10 need 15 per cent more time, rolls 11 to 15 need 15 per cent more than that — about 132 per cent of the original time — and then the litre is finished. Put the other way: a bath that has done ten rolls per litre needs a sixth of its time again to reach the same Contrast Index, and one that has done fifteen needs a third.

That is the same shape as the answer ILFORD gives for its powder developers and the same shape as Kodak’s own 15 per cent for D-76, and Part VIII’s restrainer lesson is where the reason is taught: what accumulates in a used bath is not only exhaustion but restraint, and lengthening the time compensates for the first more cleanly than for the second. Kodak’s schedule is arithmetic offered in place of chemistry, and it works because it was measured.

Replenished and seasoned, which are not the same thing

Three separate published facts have to be held apart here, because they pull in opposite directions.

A fresh, unseasoned tank develops about 10 per cent faster than the tables. Kodak’s own statement, about a working tank started from scratch in a replenished process.

But the fresh large-tank table gives shorter times than the seasoned one. TRI-X 400 at EI 400 at 20 °C is 8 minutes in Table 4, fresh, and 8½ minutes in Table 3, seasoned.

And the two tables were determined with different agitation — nitrogen burst at two seconds every ten for the seasoned tables, manual agitation once a minute for the fresh ones.

Those three facts do not straightforwardly combine, because the agitation difference confounds the seasoning difference, and Kodak does not disentangle them. This page reports all three and resolves none of it. What is safe to take away is the practical instruction Kodak does give: preseason a new tank with 6.5 mL of starting solution per litre, or expect the first films to come out thin until the tank settles.

Dilution, in time and in capacity

At 1:1 the times lengthen by between a quarter and two fifths — TRI-X 400 at EI 400 goes from 7 minutes to 9, T-MAX 100 at EI 100 from 7½ to 9½, T-MAX 400 at EI 400 from 6½ to 9¼ — in exchange for slightly greater film speed, enhanced sharpness and shadow detail, and slightly more grain. The capacity cost is larger than the time cost and less obvious: 15 rolls per litre reused, against 10 per litre at the 100 mL floor one-shot.

Keeping, and a tension this course does not resolve

Kodak’s claims are unambiguous: excellent keeping properties, good shelf life (six months after mixing when stored in full bottles), and high resistance to breakdown from oxidation during storage or in replenished processes. Its storage figures are the same shape and the same numbers as the ones it gives for D-76.

CAMEO, on the class Kodak names, points the other way: aqueous ascorbic acid is oxidised by air at a rate that depends on pH and oxygen and is accelerated by alkaline conditions, iron and copper — and degradation occurs under anaerobic conditions as well, so excluding air is not a complete defence. A bath held at pH 8.2 is on the wrong side of that line by construction.

Two Tier-1 documents, about the same chemistry, pointing in opposite directions. Part VIII’s alternative-agents lesson sets the disagreement out at length, records that the community’s usual tie-breaker — reports of ascorbate developers failing suddenly rather than gradually — is Tier-3 evidence that may not establish a chemical claim, and leaves the question open. This page does the same. The experiment that would settle it is in Experiments.

Water

Above 200 ppm of calcium carbonate, Kodak says you may need conditioned water to avoid cloudiness when mixing higher dilutions, and directs you to your water authority for the figure. Note the plural, dilutions, in a sheet that publishes exactly one — another small seam in a document that is otherwise unusually careful.

Image characteristics

Every claim in this section is Kodak’s. None of it has been measured by this course, and where a claim cannot be checked against anything the page says so.

Grain and sharpness. “Fine grain and high sharpness”, with “enhanced sharpness, especially with 1:1 dilution”. Both are relative terms with no comparator named.

The enlargeability claim, which is the odd one. The features table carries “enlargeability of negatives 10 percent greater with equivalent sharpness and grain (image quality)”. That is a quantitative claim — ten per cent — with no named comparator, no named film, no stated measurement and no definition of what is being held equivalent. It is recorded here because it is on the sheet, and it is endorsed by nothing. Part XIII is where the measurements that would test such a claim are taught.

Speed. “Full emulsion speed”, and “excellent emulsion speed with normal and push processing”, with “enhanced shadow contrast and improved highlight detail with some films” — the films unnamed. The tables are the checkable part: published times run to EI 3200 for TRI-X 400 and EI 25000 for T-MAX P3200 in a small tank.

✕A shorter development time is not a faster film, and this is where people get it wrong

Set Kodak’s own numbers side by side at 20 °C in a small tank, from the film sheets that print both developers in one table:

Film, at its nominal speed	XTOL	D-76
T-MAX 100 at EI 100	7½ min	6½ min
TRI-X 400 at EI 400	7 min	6¾ min
T-MAX 400 at EI 400	6½ min	7½ min

It is tempting to read the third row as “XTOL is faster on T-MAX 400” and the first as “XTOL is slower on T-MAX 100”. Both readings are wrong, and the reason is what the tables are indexed by.

These are times to the same Contrast Index. They measure how quickly each developer builds contrast in that emulsion, not how much shadow density it delivers for a given exposure. Film speed is a measurement made at the toe of the characteristic curve against a defined criterion, and Part XIII’s film speed lesson sets out why the two questions come apart. A developer can reach CI 0.56 more slowly and still put more density in the shadows, or the reverse.

What the rows do establish is that the relationship between the two developers is emulsion-dependent — it reverses between T-MAX 100 and T-MAX 400, two films from one maker. That is the sourced fact, and it is what Kodak’s own hedge, “with some films”, is doing.

Contrast. “Contrast Index similar to that produced by other developers”, giving “negatives with printing characteristics like those processed in other general-purpose developers”. This is a modest claim and an unusually honest one: Kodak is saying the negatives will print like negatives, which is what a general-purpose developer is for. The T-MAX 100 film sheet plots Contrast Index curves for XTOL and XTOL 1:1 alongside D-76 for small tank, large tank, rotary tube and tray, which is the closest thing to a measurement in any of these documents.

Tonality. “Enhanced shadow contrast and improved highlight detail with some films” is the whole of it. No film is named and nothing is quantified.

Colour and stain. No claim of either appears anywhere in Kodak’s literature for this product, and this page makes none. Kodak does not describe it as a staining developer in the sense Part VIII’s staining lesson uses the term, and no document in this corpus says what, if anything, an oxidised ascorbate leaves in the gelatin.

The mechanism

One class of substance is named. Everything below is either the chemistry of that class, which is established and sourced, or an inference about this product, which is labelled as one. Under Rule 7 the two are never allowed to look alike.

What is established about the named class

Ascorbate, not ascorbic acid, is what does the work at pH 8.2. The IUPAC dissociation-constant dataset gives L-ascorbic acid a pKa₁ of 4.04 at 25 °C. At the bath’s published pH of 8.20 the first proton has been gone for four pH units, so what is present is the singly ionised ascorbate anion — which is why the sodium salt exists as a photographic chemical, and why the free acid is awkward to formulate with: added as the acid it eats the alkali the same bath needs to make it active. Whether Kodak’s packets hold the acid, the salt, or both is not published.

It is not a benzene ring at all. ChEBI describes a five-membered lactone carrying a two-carbon side chain, which puts ascorbate outside every other family of developing agent in this encyclopaedia. CAMEO’s datasheet carries a one-line reactivity alert: Strong Reducing Agent.

Its driving force is set by the alkali, steeply. Mike Ware, writing on reducing agents for platinum work and citing Borsook and Keighley’s 1933 measurement, gives the redox potential of ascorbic acid as moving from −0.283 V to −0.066 V as the pH goes from 2 to 7. More than 200 millivolts across five pH units means a developing agent that is governed by its alkali rather than merely permitted by it — which is exactly what Kodak’s own 1928 primer says of every agent: that it cannot work without alkali, and that the energy of the developer follows the amount present. Part VIII’s lesson on alkalis, buffers and pH is the full account.

What follows for a bath specified at pH 8.20

It is running low, and deliberately. For comparison, ILFORD publishes 8.60 to 8.70 for the stock solution of ID-11, a packaged borax metol–hydroquinone developer of the same family as D-76 — the course’s D-76 page treats that figure as the working region of the family and labels the connection an inference, and it stays one here. XTOL sits four to five tenths of a pH unit below that band, which is a factor of roughly two and a half to three in hydrogen-ion concentration; a paper developer runs two orders of magnitude above it again, and Part VIII’s alkali lesson carries those figures with their sources.

And a low pH is bought at a price the 1928 primer names. Alkalis soften gelatin: too alkaline a developer over-swells the coating and gives trouble with frilling. A bath at 8.2 asks less of the emulsion than one at 10.4, which is one reason an ascorbate developer behaves differently in the tank — and, at 24 °C and 27 °C where XTOL’s tables still run, that margin is being spent on temperature instead.

The specific gravities are close and the pHs are not. ILFORD gives ID-11 stock a specific gravity of 1.090 at 20 °C; Kodak gives XTOL 1.085 at 25 °C. Those two numbers are not measured at the same temperature and the two products are made by different companies to undisclosed formulas, so nothing can be concluded from their similarity — it is recorded here only because a reader who has both sheets will notice it and should know that it settles nothing.

What “no hydroquinone” changes chemically

This is the one place where a negative disclosure buys real explanatory power.

There is no quinone, so there is no sulfonation route. In a metol–hydroquinone developer the oxidised hydroquinone is a quinone, and sulfite adds to it to give a sulfonate — the reaction that keeps the bath colourless while it is being consumed, and the reason Kodak warns that an MQ developer can look fresh and be exhausted. Part VIII’s superadditivity lesson sets that out and notes the consequence: whatever governs an ascorbate developer’s exhaustion, it is not that. What does govern it is not established by anything in this corpus, and the course declines the community account that ascorbate developers fail suddenly, because Tier-3 evidence may not establish a chemical claim.

And oxidation has a different catalyst list. CAMEO records that the air oxidation of aqueous ascorbate is accelerated by alkaline conditions, iron and copper, and that degradation continues even anaerobically. That is a property of the class and it is the reason Incompatibilities below has anything in it at all.

What is inference, marked as such

Three readings appear on this page and each is the course’s, not Kodak’s: that a bath holding pH to ±0.05 across a six-month life is buffered by something; that the seasoning behaviour Kodak describes is the accumulated-restraint effect the 1928 primer names; and that E103CF’s five rolls per litre is the same capacity as J-109’s fifteen, counted without time compensation. None of the three names a substance, and none of them is a step towards a formula. They are offered because a page that reports observations and refuses to think about them is not teaching either.

The nearest open formula

Kodak D-76, and the choice is Kodak’s own rather than this course’s: the two developers are printed in adjacent columns of the same tables, for the same films, at the same temperatures, in three separate Kodak Alaris film sheets and in the chemicals comparison sheet.

Where they are the same

Both are general-purpose black-and-white film developers from one company, sold as powder, made up to a final volume, used at full strength in a small tank, a tray, a rotary tube or a large tank, or diluted 1:1 for one-shot work that is never reused or replenished. Both are reused with a published time compensation of 15 per cent. Both are replenishable. Both aim at the same Contrast Indices, and Kodak’s own tables show them landing within about a minute of each other on every film in this corpus.

Where the product wins, on Kodak’s own published figures

	XTOL	D-76
Useful capacity, 8 × 10 sheets per gallon (litre)	19 (5)	16 (4)
Working solution life in a tank	2 months	1 month
Replenisher	itself, 70 mL per roll	D-76R, a different formula
Published pH and specific gravity	8.20 ± 0.05, 1.085 ± 0.003	none published
Hydroquinone	none	5 g per litre

Capacity and tank life come from one row of one Kodak table read against the row beneath it, which is as clean a comparison as this formulary ever gets. The replenisher difference is the largest practical one: D-76R carries one and a half times the metol and hydroquinone of the working bath and ten times the borax, because a tank in use loses its alkali reserve first — so a replenished D-76 line needs two formulations, two stocks and two labels, where an XTOL line needs one solution and one number.

Where the comparison is weak, which is exactly where a reader wants it

Chemistry. D-76 is metol 2 g, sodium sulfite 100 g, hydroquinone 5 g and borax 2 g in a litre, each with a function that can be named, changed and observed. XTOL is “ascorbic acid-based” and “no hydroquinone”. On the published evidence the two developers share not one named ingredient. So this is a comparison of use, capacity, cost and behaviour — and it cannot be a comparison of composition, because only one of the two has one.

And there is no closer relative to offer. This formulary contains no open ascorbate film developer. The nearest thing to one is 510-Pyro, which does contain five grams of ascorbic acid — but as a partner to ten grams of pyrogallol in a hundred millilitres of triethanolamine, with no water and no sulfite anywhere in it, producing a proportional stain. That is a different kind of object doing a different job, and calling it XTOL’s nearest relative because both contain an ascorbate would be a worse answer than D-76, not a better one. The honest statement is that the course has an ascorbate chemistry and no ascorbate formula, and this page is where that gap shows.

So which should you use

If the question is what should I put in the tank tonight, the tables above are Kodak’s answer and they are good ones. If the question is what should I mix, it is D-76, because you can mix it, and because everything Part VIII teaches — the alkali, the sulfite as preservative and as silver solvent, the superadditive pair, the restrainer — is visible in it and invisible here. Most readers of this course should do both, and the comparison is written up as an experiment below.

Safety

Why Level B

Two criteria of Level B are met and the first criterion of Level A cannot be shown to be met at all.

It is a fine powder that must not be inhaled — on the form alone. Two packets are torn open and tipped into water, and Level B names powders explicitly. Princeton’s guidance is the general form: prefer a liquid concentrate where one exists, and where a powder must be mixed, use a glove box, local exhaust or a rated dust respirator. This product has no liquid form.

And the composition is unknown. Level A’s first criterion is that every substance’s GHS classification is at most irritant, harmful if swallowed, or corrosive at the concentrations actually handled. That is a test against a classification, and there is no classification here to test against, because no safety data sheet could be obtained. The course does not assume a hazard classification it has not read. An unknown powder is handled at the more protective level until a sheet says otherwise; if you obtain current sheets and they support Level A, that is a better assessment than this one and you should use it.

Kodak’s own instruction, which is stricter than most

J-109’s own handling paragraph, in the maker’s words: when you mix solutions, wear goggles or a face shield, a protective apron, and protective gloves made from neoprene or nitrile rubber. Clean protective clothing after use to remove chemical residue that can cause contamination. Consult the chemical labels and the safety data sheets for the specific chemicals.

A face shield is a stronger recommendation than most photographic literature gives for mixing a developer, and the apron and the clothing-cleaning instruction are about carry-over contamination rather than about acute injury. The gloves page is where the material choice is worked out and the PPE SOP is the order of operations.

The dust is the moment of highest exposure

Nothing else in the process brings you as close to as much of the material. HSE’s COSHH essentials sheet for manual film and plate development is written for exactly this workflow, and the controls it names — mixing in a well-ventilated area, avoiding raising dust, gloves and eye protection, washing before eating — are the ones that apply. The SOP for weighing a solid and the SOP for mixing a developer are the bench procedures, and Part II’s PPE lesson is the reasoning behind them.

Pour slowly and low into the water, at arm’s length, with the extraction on. Do not tip from height, do not shake the packet, and do not do it in the same movement as a breath.

What “no hydroquinone” removes, and what it does not

It removes one named, classified substance from the risk assessment, and it is not a trivial one: on the comparable ILFORD product, part A declares hydroquinone at 50–70 per cent, carrying H341, suspected of causing genetic defects, and H351, suspected of causing cancer. Nothing in the XTOL packets is that substance, because Kodak has said so in print.

It removes nothing else. The absence of one named substance says nothing about the others, and darkroom dermatitis is the classical hazard of developer handling in general: Kodak’s own safe-handling publication records that photographic developers may cause allergic contact dermatitis as well as irritative, that skin abrasions and cuts should be protected because broken skin increases the risk, and gives an unusual and practical instruction — if you get an alkaline solution such as developer on your skin, wash with a pH-balanced cleanser rather than an ordinary soap, because ordinary soaps are themselves alkaline and may be less effective.

And the classification of the one substance named is not a licence

PubChem’s aggregation of the ECHA inventory gives ascorbic acid no signal word, no pictogram and no hazard statement. That is a statement about pure ascorbic acid, not about two packets of unknown mixture, and HSE’s EH40 says in its own introduction that absence from the list of workplace exposure limits does not indicate that a substance is safe. Gloves, eye protection and ventilation go on regardless.

Storage

The powders: unopened, cool and dry — and no published figure. J-109 gives storage lives for solutions only, under a heading that says so. There is no shelf life for a sealed packet, no shelf life for an opened one, and no instruction about a part-used packet. ILFORD, on the comparable product, tells you to prepare the stock solution immediately once the packets are opened; Kodak says nothing, so the sensible practice is the one that needs no source: mix a whole pack at a time, which the make-up volumes assume anyway, and do not store a half-emptied packet.

The mixed developer: full bottles, and the reason is printed. Six months in a full, tightly closed container; at least two months in a partially filled one; indefinitely in a replenisher tank with a floating lid that is being topped up. Kodak’s instruction is to minimise the air space, because partially filled containers allow oxidation of the solution.

The practical consequence is the one every developer page in this formulary reaches: decant as you use. A litre in five 200 mL bottles filled to the neck keeps like five full bottles; the same litre in one bottle emptying by fifths keeps like a half-empty one from the second pour onwards. Label and date every one — the labelling SOP — and rotate them by date rather than by position.

The working solution in a tray is 24 hours, on Kodak’s chemicals comparison sheet, against two months in a covered tank. A tray is a large surface of solution in contact with a room.

Diluted 1:1, there is no storage question, because there is no storage: mix it immediately before use and discard it after one batch.

In a processor, Kodak’s maintenance list is short and worth borrowing even for a deep tank: minimise air access with floating lids, rinse the developer off parts left exposed after shutdown, replace evaporation losses with water at start-up, and check recirculation filters.

Incompatibilities

Kodak publishes none. J-109 has no incompatibility section, no reactivity section and no section 10, because it is a technical data sheet and not a safety data sheet — and the safety data sheet, which would have had all three, could not be obtained. That absence is the honest headline of this section.

What can be said falls into two groups.

The universal darkroom rule, which needs no composition. This is a developer, so the acid baths that follow it are its opposite: stop bath and fixer carried back on a funnel, a graduate or wet fingers will neutralise it and contaminate it. Dedicated, labelled utensils for the developer, and a one-way workflow across the bench, are the controls, and Part II’s storage and incompatibilities lesson and the incompatibilities reference are where the general case is set out.

The one class-specific hazard, which is about keeping rather than about danger. CAMEO’s reactivity profile for ascorbic acid names oxidisers, alkalis, and iron and copper — the last two as accelerators of the air oxidation of aqueous solutions, along with heavy-metal salts of copper, zinc and manganese. For a developer whose maker sells it on oxidation resistance, that turns a chemical incompatibility into a practical one: a rusting tank lid, a brass fitting on a mixing tap, or a hard water supply carrying iron is a shelf-life problem, not merely an untidiness. That this applies to the product, rather than to pure ascorbate in a beaker, is an inference from the one class Kodak names, and it is offered as a precaution rather than as a finding.

Hard water is Kodak’s own warning: above 200 ppm of calcium carbonate, conditioned water may be needed to avoid cloudiness.

And the thing not to infer. With no safety data sheet there is no section 10, so nothing on this page licenses the conclusion that any particular substance is safe to mix with this developer. Absence of a warning is not a clearance.

Waste

Kodak’s own guidance gives developer four routes and withholds one. In Table I of its environmental guidelines for amateur photographers, the row for Developer, unused and used, carries a tick against discharge to the sewer, against household hazardous waste collection, against discharge to a nearby publicly owned treatment works, and against Kodak’s own collection programme — and a dash against municipal trash, for the stated reason that refuse collectors would not know the material was there and could come into contact with it.

Four qualifications turn that into something usable.

It is a statement about “developer” as a class, not about XTOL by name. With no safety data sheet there is no section 13 and no waste classification for this product. The row above is the closest thing in Kodak’s own literature.

Septic systems are not treatment plants. Kodak states plainly that they are not designed to treat photographic processing solutions, and gives septic users the other three routes instead.

Do not combine it with the fixer. Kodak’s own figures put the silver in a developer at negligible levels, so mixing developer into fixer recovers nothing and spoils the one stream that is worth recovering. Developer, fixer and stop go into three separate labelled bottles — the general chemical waste SOP and the silver-bearing waste SOP — and Part II’s chemical and silver waste lesson is the reasoning.

And the jurisdiction decides. Kodak’s table is written for the United States. ILFORD’s route for domestic users in the United Kingdom is a separately bottled, labelled container taken to a Household Waste and Recycling Centre, and a drain discharge that is lawful in one country is an offence in another. The disposal caveat governs everything in this section.

Troubleshooting

The solution is still coppery after Part B has fully dissolved. Kodak ties the clearing of the tint to the addition of Part B, so a solution that stays copper-coloured is not what the sheet describes. The sheet gives no remedy. Check first that Part B went in second and dissolved completely, that the water was within 18 to 30 °C, and that the volumes were right — then measure the specific gravity and pH against 1.085 ± 0.003 and 8.20 ± 0.05 at 25 °C, which is what those figures are for.

The specific gravity or pH is out of tolerance. Kodak’s own conditional is if correctly mixed, so treat an out-of-spec batch as a mixing fault before treating it as a product fault: a make-up volume short or long, a powder not fully dissolved, or a pack mixed to the wrong final volume. Verify the measurement before you condemn the batch — the pH meter calibration SOP and the glassware verification SOP, and Part II on measurement and uncertainty.

Negatives thinner and flatter as a session goes on. The reuse ladder has not been applied. Rolls 6 to 10 per litre need 15 per cent more time and rolls 11 to 15 another 15 per cent on top of that; without it the symptoms are a flat negative and a low contrast index that drift steadily rather than jumping. Past fifteen rolls per litre it is exhausted developer and the answer is a fresh litre.

A whole batch thin at 1:1, at the correct time and temperature. The most likely cause is the one Kodak names: less than 100 mL of full-strength developer per 80 square inches in the mixture, so the bath covered the film but did not contain enough active ingredients to develop it fully. Thin negative is the diagnostic page; the fix is arithmetic, not time.

Mottling, streaks or surge marks on short times. Table 1 warns below five minutes and Tables 2 to 8 below four, and several published rows fall under those thresholds at 24 and 27 °C. Work cooler and longer rather than hotter and shorter — mottled development, surge marks and bromide drag.

A cloudy working solution on mixing. Kodak’s stated cause is water above 200 ppm calcium carbonate, and its remedy is conditioned water for higher dilutions.

A bottle that was fine last month and is dead this month. A partly filled bottle is Kodak’s own named failure mode — partially filled containers allow oxidation of the solution — and “at least two months” is a floor, not a promise. See oxidised developer, and decant into full bottles next time. An unlabelled or undated container turns this from a diagnosis into a guess.

A newly filled replenished tank running about 10 per cent fast. Not a fault: Kodak says an unseasoned tank does exactly that until it reaches a steady state. Preseason it, or ride the times down.

Contrast wrong after switching to XTOL from another developer. Expected, and Kodak’s own conversion procedure addresses it: match Contrast Index rather than time, using control strips before and after. The control-strip SOP and the developer-exhaustion control chart are the tools; Part IX’s fault-diagnosis lesson is the method.

Experiments

Each of these tests something Kodak publishes, which is the only reason they can be run at all: a product whose maker publishes nothing is a product you cannot argue with. Part IX’s experimental design lesson is the discipline — one variable, a control, a hypothesis written before the result.

1. Verify the acceptance specification. Mix one pack. Measure the specific gravity with a hydrometer covering 1.000 to 1.200 and the pH with a calibrated meter, both at 25 °C, and compare with 1.085 ± 0.003 and 8.20 ± 0.05. Then deliberately mis-make a second litre — 900 mL final volume instead of 1000 — and measure again, to find out how large a mixing error the specification actually catches. This is the rare case where a manufacturer hands you a pass/fail criterion for your own bench technique.

2. Test the capacity reconciliation. The claim in What the maker publishes is that E103CF’s five rolls per litre and J-109’s fifteen are the same capacity counted with and without time compensation. Process fifteen 135-36 rolls through one litre, each carrying an identical step-wedge exposure, following the compensation ladder; plot Contrast Index against roll number. If the ladder holds CI flat to fifteen, the reading is supported. If CI falls from roll six onwards, it is not. Part XIII’s interpreting-density-data lesson is how the plot is read.

3. Full strength against 1:1 at matched contrast. Develop identical step-wedge exposures to the same Contrast Index at each strength — 7 minutes and 9 minutes for TRI-X 400 at 20 °C — and compare the negatives for edge effects rather than for density. Kodak claims enhanced sharpness at 1:1; Part VIII’s acutance lesson gives the method for seeing whether the claim survives a matched-contrast comparison.

4. The keeping question, which is the interesting one. Mix one litre and split it: one bottle filled to the neck, one half-filled, both tightly closed, both dark, both at the same temperature. Sample each at intervals and test activity against a fogged-strip or step-wedge standard. This is the experiment that would put evidence into the standing disagreement between Kodak’s high resistance to breakdown from oxidation and CAMEO’s account of ascorbate solutions, and it is the same design the aerial oxidation experiment runs on hydroquinone. Nothing on this page can tell you the answer.

5. Seasoning, isolated from agitation. Kodak’s fresh and seasoned tables differ and were determined with different agitation, so the published numbers cannot separate the two effects. Run one bath fresh and one preseasoned with 6.5 mL of starting solution per litre, holding agitation identical, and plot CI against time for both. This is a variable Kodak has confounded and you can un-confound.

6. XTOL against D-76, the comparison the tables invite. One emulsion, one exposure, matched Contrast Index, both developers at 20 °C in the same tank with the same agitation. Compare grain, edge effects and shadow density, and read the result against the developing-agent comparison experiment. Because you mixed one of the two from four weighed chemicals, you can then do what you cannot do with the other: change the sulfite, or the borax, and run it again.

7. The experiment not to run. Do not attempt to infer the composition from the specific gravity, the pH, the mixing sequence or the colour change. Every route from those figures to a formula passes through an assumption about what is dissolved, which is the thing being asked. A page that did it would look exactly like this one with better numbers, and it would be wrong.