ILFORD MICROPHEN developer

Two paper bags in a carton, one small and one large, and a claim on the front of the sheet that this developer will get you half a stop more film speed than the developer ILFORD measured the film’s speed in. That claim is checkable, because HARMAN prints MICROPHEN, ID-11 and PERCEPTOL in three adjacent columns of one table. What is not checkable is anything about what is in the bags. ILFORD’s technical sheet does not give a composition; it does not even name the developing agents. The only ILFORD document that names them is a hazard sheet, and this page reads it as one.

HARMAN technology Limited (ILFORD Photo) — sold as two part powder

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

Component	Concentration as the sheet gives it	Hazard codes
Hydroquinonenamed on the sheet as 1,4-dihydroxybenzenehydroquinonequinolCAS 123-31-9One of the two developing agents named on part A's own product identifier, and the one whose band lies wholly above the other's	50-70%	H302, H317, H318, H341, H351, H400, H410
Sodium metabisulfitenamed on the sheet as sodium metabisulphiteCAS 7681-57-4	30-40%	H302, H318
Boric acidCAS 10043-35-3	1-5%
Phenidonenamed on the sheet as 1-phenyl-3-pyrazolidoneCAS 92-43-3The other developing agent named on part A's product identifier; with the hydroquinone it makes MICROPHEN a phenidone-hydroquinone developer, which is the one compositional fact the two sheets settle	1-5%	H302, H317, H400, H410
Sodium sulfite (anhydrous)named on the sheet as sodium sulfiteCAS 7757-83-7	60-100%
Borax (sodium tetraborate decahydrate)named on the sheet as Sodium tetraborate decahydrateCAS 1303-96-4	<8.5%	H360FD

Not disclosed. HARMAN publishes no composition for MICROPHEN, and its technical sheet does not even name the developing agents: the only document in ILFORD's literature that names them is a hazard sheet. Two safety data sheets name six components between them and give each a concentration band for the purpose of classifying a hazard, which is not an assay - the bands are wide enough that part A's upper limits total 120 per cent of a bag and its lower limits only 82, and the sheets are for the two bags separately, so nothing published anywhere says what mass of part A meets what mass of part B. Neither table names a restrainer of any kind. No quantity, no ratio between the two developing agents, no alkali loading, no antifoggant, no working-solution pH at either dilution and no formulation date appears in any ILFORD document this course holds. A reader who wants to know why it is faster than ID-11, or to move one term and watch what happens, has to mix an open formula instead of buying this one.

Nearest open formula. Kodak D-76 — Both are fine-grain borax film developers mixed from powder, used at stock strength in a tank at 20 degrees C or diluted for one-shot work, and reused with a published time compensation. D-76 is published in full and made from four weighed chemicals whose functions can each be named and changed one at a time; MICROPHEN arrives as two sealed bags whose maker names two developing agents on a hazard sheet and nothing else anywhere. D-76 pairs metol with hydroquinone and claims full film speed; MICROPHEN pairs a pyrazolidone with hydroquinone and claims a speed increase of up to half a stop, more on the fast films, which is a claim about beating ID-11 - the developer ILFORD states its own ISO speeds were measured in. On HP5 Plus, ILFORD publishes MICROPHEN stock at six and a half minutes for EI 400 against ID-11's seven and a half, eleven minutes against fourteen at EI 1600, and a time at EI 3200 where ID-11's column is blank. What you give up is a published pH for the bath you actually stand over, an alkali you can weigh, a replenisher, and the ability to move one term and see what it does.

⚠Which bag carries the Danger label, and why it is not the one you would guess

Both bags are labelled Danger, and for different reasons.

Part A, the small bag with the developing agents in it, is classified a skin sensitiser, a suspected mutagen and a suspected carcinogen, and carries the supplemental statement EUH031, contact with acids liberates toxic gas.

Part B, the large bag that looks like a bag of salt, is classified Repr. 1B, H360FD - may damage fertility, may damage the unborn child. That is its whole classification: one pictogram, one hazard statement, and it is the more serious of the two label warnings. It is there because of the borax, and part A carries boric acid as well.

A person who is pregnant, breastfeeding or trying to conceive should not be the one who opens these packets. See Safety below for what follows.

Purpose

To develop a black and white negative exposed at a meter setting above the one the film’s speed was rated at, without paying for it in grain. ILFORD’s own words: MICROPHEN “is a fine grain film developer which gives an effective increase in film speed. A speed increase of up to half a stop can be achieved with most films but with faster films such as HP5 Plus, Delta 400 Professional and Delta 3200 Professional it is more.” And then the part that says what kind of developer it is: “Many developers that give an increase in film speed usually produce a corresponding increase in grain size, MICROPHEN is formulated to overcome this disadvantage, the low alkalinity of the developer reduces grain size and grain clumping. Therefore, MICROPHEN is said to have a high speed/grain ratio.”

That claim has a precise meaning, and it is worth pinning down before anything else on this page. ILFORD states, on its own film sheets, that its films’ ISO speeds were measured in ID-11. DELTA 400 Professional “has a speed rating of ISO 400/27° to daylight. The ISO speed rating was measured using ILFORD ID-11 developer at 20 °C/68 °F with intermittent agitation in a spiral tank.” DELTA 3200 Professional’s ISO rating of 1000/31° carries the same sentence. So a MICROPHEN speed increase is not a vague marketing gain over developers in general: it is a gain over the specific developer the number on the box was determined in, sold by the same company, in the same carton range, printed in the adjacent column of the same table. Part XIII’s film speed lesson is where that distinction — criterion speed, ISO speed, exposure index — is worked out properly, and it is the lesson to read before you believe or disbelieve half a stop.

Recommended uses

Push-processing a fast film in a spiral tank, at stock strength, at 20 °C. This is the use every part of ILFORD’s literature points at. The powder sheet says MICROPHEN “is particularly useful when using extended development times to push process fast films such as HP5 Plus, Delta 400 Professional, Delta 3200 Professional and SFX200”. The film sheets agree: in every ILFORD film sheet in this course’s corpus that carries a Maximum film speed row, the powder named in it is MICROPHEN at stock strength — DELTA 100 at EI 200, FP4 Plus, DELTA 400 and HP5 Plus at EI 3200, SFX 200, and DELTA 3200 up to EI 25000. PAN F Plus, the slowest film in the range, has no such row at all, which is its own kind of statement.

At a film’s box speed, when you want the extra half stop in the shadows rather than on the meter. The times are shorter than ID-11’s at the same meter setting — six and a half minutes against seven and a half on HP5 Plus, six and a half against nine and a half on DELTA 400 — and what that buys is development reaching further into the weakly exposed grains. What it costs is discussed under Image characteristics.

Diluted 1+1 or 1+3 as a one-shot developer, mixed from the stock immediately before use and thrown away. ILFORD publishes both dilutions for most films at box speed and stops publishing them as the meter setting rises: HP5 Plus has a 1+3 time at EI 400 and none at EI 800 or above.

Sheet film in a dish or tray, at stock strength only. Continuous agitation is used — the film fully immersed and the dish gently rocked — and ILFORD says continuous agitation reduces the recommended development times by about 15 per cent. Higher temperatures are explicitly not recommended for dish work because the times become too short.

Deep tanks with a floating lid, where the stock keeps four months against one month without the lid, and where ILFORD gives a specific manual agitation: lift the rack, tilt it, return it, three times at the end of each minute, alternating the direction of tilt.

Rotary tube processors, at stock, 1+1 or 1+3, with two instructions worth having: no pre-rinse, because it can lead to uneven development, and a reduction of around 15 per cent in the given times to compensate for the continuous agitation.

Not for anything ILFORD does not document. The nine-page sheet is a film sheet. It gives no paper instruction, no plate instruction and no reversal instruction, and this page does not supply one.

When another formula is preferable

• When you want to understand a fine-grain film developer rather than use one, mix D-76. Four chemicals, published since 1928, every quantity changeable one at a time. It is the comparison this page is built around.
• When you want the borate buffer this product appears to use, published, mix D-76d. It is the only formula in this library carrying both borax and boric acid, which is exactly the pair MICROPHEN’s two safety data sheets disclose between them — and Kodak prints both quantities.
• For finer grain than this, at the cost of speed, D-23 drops the hydroquinone and the alkali altogether, and DK-20 adds a thiocyanate silver solvent. ILFORD’s own answer in the same carton range is PERCEPTOL, which is a bought product whose page this course has not yet written.
• For high contrast, D-19 exists for that and no fine-grain borax developer does it.
• For maximum sharpness in a one-shot bath, Beutler’s two-solution developer and Rodinal are the open high-acutance formulas, and both are published in full.
• When you need a replenished tank rather than a reused one. MICROPHEN has no replenisher. ILFORD’s own replenishable powder is ID-11; the open equivalent is D-76 with D-76R, which restores capacity with no time increase at all where MICROPHEN’s reuse scheme asks for 10 per cent more time on every successive film.
• When you cannot buy a whole litre’s worth at a time. The sheet forbids making up part of a pack. If your darkroom uses 300 mL a month, an open formula you weigh is the only way to mix 300 mL.

What the maker publishes

A great deal, and the amount of it is the reason a product page can be useful at all.

The pH and the specific gravity, which are the rarest of these figures. ILFORD prints a table for fresh solutions of all three powder developers. MICROPHEN stock reads 8.67 to 8.93 with a specific gravity of 1.095 at 20 °C. At 1+1 the sheet gives a specific gravity of 1.050 and at 1+3 1.024 — and no pH at either dilution, which is a gap and not a rounding. ILFORD adds that the figures were obtained under carefully controlled laboratory conditions, that a user’s own measurements may differ slightly, and that the right use of the table is to measure your own fresh solution and compare later ones against it. That is better advice than the number.

Enough of the table to check the table. The three specific gravities are not independent, and running the arithmetic on them is a two-minute exercise that tells you the sheet was measured rather than guessed. A stock solution of specific gravity 1.095 has a density excess over water of 0.095. Halve it for 1+1 and you predict 1.0475; the sheet prints 1.050. Quarter it for 1+3 and you predict 1.02375; the sheet prints 1.024. The two predictions land within about two and a half parts and a quarter of a part in a thousand respectively — close enough to confirm the dilutions, and not exact, because volumes of solutions are not strictly additive. Do the same for ID-11 and PERCEPTOL in the adjacent columns and they behave the same way.

The mixing method, in enough detail to be a procedure. Dissolve part A, the smaller bag, in about three quarters of the total solution volume of warm water at about 40 °C. Stir until most of it has dissolved, then keep stirring while gradually adding part B. Keep stirring until no more powder dissolves — and ILFORD says plainly that it is normal for a few grains to remain undissolved, and that discoloured or darker particles in the white powder are normal and will not affect development. Add cold water to the final volume, stir, and let it cool to 20 °C. Two further instructions that are chemistry rather than housekeeping: never make up a fraction of a pack, and draw your water off and let it stand a few minutes first, because most water from a pressure main is highly aerated.

Development times for ten ILFORD and Kentmere films, at three dilutions, at meter settings from EI 25 to EI 25000, with the contrast they are meant to produce stated: negatives of normal contrast, “typically around a G-bar of 0.62”. That figure ties the whole table to Part XIII’s account of average gradient, and it is what makes the times adjustable rather than magical: if you want more contrast, develop longer, and the sheet says so.

A temperature rule with a worked example. The developers may be used from 20 to 24 °C. Increase the time 10 per cent for each 1 °C drop and decrease it 10 per cent for each 1 °C rise, or use the time-temperature graphs. ILFORD’s own example: 6 minutes at 20 °C becomes 4½ at 23 °C and 9 at 16 °C.

Four agitation regimes, each specified. Spiral tank: four inversions in the first 10 seconds, four inversions in the first 10 seconds of every subsequent minute, tap the tank after each. Dish: continuous, gentle rocking, times cut by about 15 per cent. Deep tank: lift, tilt, return, three times at the end of each minute alternating the tilt. Gas burst: nitrogen for the developer, never air, 0.3 to 0.9 bar, two seconds on and eight off as a starting point. And a general instruction — drain the developer ten seconds before the end of the time.

The reuse scheme, with a table. A litre of stock does 10 roll films if reused, which is exactly ILFORD’s figure for ID-11 and two and a half times its figure for PERCEPTOL. The compensation is 10 per cent more time for each successive film, and the table makes clear it is arithmetic and not compound: film 2 at N+10 per cent, film 10 at N+90 per cent, not 1.1 raised to the ninth power. In larger volumes the step is taken after each batch — every five films in five litres, every twenty-five in twenty-five.

Six keeping figures, not one: six months in a full capped container, one month in a half-full one, four months in a deep tank with a floating lid, one month without, indefinitely for unopened packets at 4 to 20 °C, and 24 hours for anything diluted.

The rest of the process. ILFOSTOP at 1+19 for 10 seconds, 15 films per litre. RAPID FIXER or HYPAM at 1+4 for 2 to 5 minutes, 24 films per litre. A wash of 5 to 10 minutes running water, or ILFORD’s own economical alternative — fill and invert five times, refill and invert ten, refill and invert twenty. ILFOTOL at 5 mL per litre. Dry at 30 to 40 °C.

And an unusually candid paragraph about why reuse is a compromise. Reusing developer, ILFORD writes, “lowers image quality slightly and increases the risk of physical damage”; the developer oxidises, precipitates may form, tiny particles of emulsion from earlier films may be held in suspension, and there is a risk of miscounting. One-shot processing “eliminates or greatly reduces these problems”. A maker arguing against the economical use of its own product is worth quoting.

What is not disclosed

The formula, and further than usual. ILFORD’s paper-developer sheet at least calls BROMOPHEN a phenidone/hydroquinone developer in its product description. The powder film developer sheet names no developing agent at all, for any of the three products, in nine pages. Not the agents, not the alkali, not a quantity, not a ratio, not a restrainer, not a sequestrant, not the date the formulation was fixed. The word “phen” in the trade name is not evidence and this page does not treat it as any.

So the only ILFORD document that names the agents is a hazard sheet. That inversion is worth noticing. Everything the table above contains was published because the law requires a mixture’s hazards to be communicated, not because HARMAN chose to describe its product.

!Why the bands cannot be added up, and why they cannot even be combined

The temptation with a composition table is to treat the percentages as an assay and solve for the rest. With MICROPHEN there are two separate reasons that fails, and the second is the one that finishes the argument.

First, the bands are far too wide. Add the upper limits of part A’s four bands — 70, 40, 5 and 5 — and you get 120 per cent of a bag. Add the lower limits — 50, 30, 1 and 1 — and you get 82 per cent, leaving nearly a fifth of the bag unaccounted for by any named substance. Part B is worse: its two bands run from 60 per cent to 108.5 per cent. Both totals are the course’s arithmetic on HARMAN’s printed figures, and neither is a composition. Part A’s sheet adds its own admission in section 2: “5 percent of the mixture consists of ingredient(s) of unknown toxicity” — which is a statement about missing acute-toxicity data for the classification calculation rather than about unnamed substances, but it is not the sentence you would write about a table you regarded as an assay.

Second, and decisively, there are two tables and no bridge between them. These are the compositions of two separate bags. Nothing published anywhere states what mass of part A meets what mass of part B. Even if both tables were assays — and they are not — they could not be combined into a formula for the litre of developer, because the mass ratio of the small bag to the large one is not published. The two sheets share a product code, 1173875, and that is the entire link between them.

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

No restrainer is named, in either table. This is the most interesting silence on the page. BROMOPHEN discloses potassium bromide and benzotriazole; MULTIGRADE discloses both as well. MICROPHEN’s two composition tables between them name two developing agents, a sulfite, a metabisulphite, a borax and a boric acid, and no antifoggant of any kind. Whether that is because there is none, or because whatever is present falls below the concentration at which the sheet must name it, is not published and this page does not guess.

And a ghost in the regulatory section. Part B’s section 15.1 lists, under the UK REACH Annex XVII restrictions line, “Toxic to reproduction: category 1B (1303-96-4), Potassium bromide (7758-02-3)”. Potassium bromide appears nowhere in the composition table of either part. On the MULTIGRADE sheet a comparable line was read as HARMAN naming a constituent, because every other name on that line came from the composition table. Here that reading does not hold: the borate is from the table and the bromide is not, so the line is as consistent with a template artefact from the sheet-generating software as with a disclosure. This page therefore does not treat potassium bromide as a disclosed component of MICROPHEN, and says so rather than leaving the reader to notice the name and draw a conclusion.

Every measurable property, refused. Section 9 of both sheets is a column of the words Not known: appearance “Solid”, and then colour, odour, pH, melting point, density, solubility, partition coefficient, decomposition temperature — all “Not known”. The company that publishes a stock pH band and a specific gravity to three decimal places in its technical sheet declines to publish either in its hazard sheet.

Nothing about why. No source in this course’s corpus says why MICROPHEN is faster than ID-11, what its alkali loading is, whether the pyrazolidone is phenidone rather than one of its substituted relatives in the current formulation — the sheet names 1-phenyl-3-pyrazolidone, which settles that question for the 2024 sheet and for no other year — or what the formulation looked like when the name was registered. Those are the interesting questions and the literature does not touch them.

Disclosed components

Every component in the table above, in the order the two safety data sheets print them: part A first, the small bag, then part B. The concentration against each is the band the sheet states and not a quantity, and a function is given only where the maker names one or where the identification is not in doubt.

Part A — the smaller bag

1,4-dihydroxybenzenehydroquinonequinol, CAS 123-31-9, 50–70 %. This is hydroquinone, and the mangled name is the sheet’s own: it runs three synonyms together with no separator between them. It is the largest named component of part A and it supplies almost the whole of that bag’s hazard classification — H302, H317, H318, H341, H351, H400 and H410 — which is why the small bag is labelled a suspected mutagen and a suspected carcinogen. It is also one of the two developing agents HARMAN names, on the product identifier line of section 1.1. Its band and the pyrazolidone’s do not overlap at any point, so the ordering between the two agents is the sheet’s own and not a reading: there is far more hydroquinone than pyrazolidone. How much more is not published, and two bands are not a ratio.

Sodium metabisulphite, CAS 7681-57-4, 30–40 %. Sodium metabisulfite is the second-largest named component of part A and the narrowest band on either sheet. HARMAN gives it no function. Two things about it are the maker’s own statements rather than inferences. First, it is named on part A’s product identifier alongside the two agents, so HARMAN treats it as a labelled constituent. Second, it is why part A carries EUH031, contact with acids liberates toxic gas — the gas being sulfur dioxide, and the acid being any acid, including the stop bath in the next tank. What the metabisulphite is doing photographically is not stated. In developer formulation generally, a metabisulphite dissolves to give bisulfite, which is a mildly acidic sulfite; packing it in the same bag as the two developing agents gives an acidic, oxygen-scavenging solution for them to dissolve into, which is consistent with ILFORD’s instruction to dissolve part A first and part B afterwards. That is the course’s reading of an instruction and a component list, and HARMAN does not say it.

Boric acid, CAS 10043-35-3, 1–5 %. Boric acid is the component that makes this sheet worth reading carefully, and it is where a reader learns that a safety data sheet can disagree with itself.

In section 3.2, the composition table, boric acid’s hazard column reads “Not classified” and its pictogram column reads “None”. Five pages later, in section 15.1, the same CAS number appears twice: once on the UK REACH Candidate List of Substances of Very High Concern for Authorisation, and once on the Annex XVII restrictions line, as “Toxic to reproduction: category 1B (10043-35-3)”. Both statements are HARMAN’s, on the same seven-page document.

They are not, strictly, a contradiction — a component present below the concentration at which it drives a mixture’s classification can honestly be shown with no hazard codes in a composition table while still being, in itself, a substance of very high concern — but a reader who stopped at section 3.2 would conclude that the boric acid in this bag was harmless, and would be wrong. This course’s own boric acid page records the ECHA aggregate: H360, may damage fertility or the unborn child, in 88.7 per cent of the 2,123 company reports that classify it. The resolution of the two sections is a reading of how CLP composition tables work and is marked as one; the safety consequence is not a reading, and it is in the Safety section below.

What the boric acid is doing is not stated either. In developer formulation it is the acid half of a borate buffer, and part B carries the other half. That pairing is the subject of The mechanism and is an inference throughout.

1-phenyl-3-pyrazolidone, CAS 92-43-3, 1–5 %. This is phenidone, John David Kendall’s Ilford compound, and it is the substance that makes MICROPHEN what it is. It shares its band with the boric acid and it is the smallest-named of the two developing agents, which is the signature of a superadditive pair: a very small quantity of one agent transforming the behaviour of a much larger quantity of another. Its classification is H302, H317, H400 and H410 — one category milder than hydroquinone’s on the aquatic axis, and a sensitiser like it.

The chemical page carries Kendall’s own quantitative claim, that a fifth to a sixth of the metol’s weight of phenidone substitutes for it, and it is worth reading before you assume MICROPHEN is D-76 with the metol swapped: that ratio is a patent’s claim about substitution in a metol–hydroquinone developer, not a statement about this product, and the course does not transfer it to MICROPHEN.

Part B — the larger bag

Sodium sulfite, CAS 7757-83-7, 60–100 %. Sodium sulfite is the largest named component of the whole product and carries the widest band on either sheet — a range of forty points of the bag’s mass, and one that runs all the way to 100 per cent. HARMAN marks it “Not classified” and gives it no function, no exposure limit and no pictogram, which is why part B’s label says nothing about it at all.

That is the reverse of its photographic importance. In a fine-grain film developer, sulfite does three jobs — it consumes dissolved oxygen, it intercepts the quinone that hydroquinone becomes, and at high concentration it dissolves silver halide, which is what makes a developer fine-grain in the first place. Part VIII’s lesson on sulfite and preservation and its lesson on solvent action and grain are the accounts, and D-76 is where you can see the quantity: 100 g in a litre, published. That sulfite is doing those jobs here is the course’s reading of a component list against the maker’s grain claim; ILFORD states none of it.

Sodium tetraborate decahydrate, CAS 1303-96-4, less than 8.5 %. This is borax, and it is the only component of either bag that HARMAN classifies as anything serious: Repr. 1B, H360FD, with the GHS08 pictogram. It is named on part B’s product identifier, it is on the UK REACH Candidate List as disodium tetraborate anhydrous, it is on the Annex XVII restrictions line as toxic to reproduction category 1B, and it is the sole reason part B as a whole is classified Repr. 1B and labelled Danger.

Borax is the classical weak alkali of the fine-grain developer, and the D-76 page is where this library sets out why: a developer’s energy follows the amount of alkali present, borax supplies very little of it, and the consequence is a bath that develops steadily, keeps its shadows and does not clump grain. MICROPHEN’s published stock pH of 8.67 to 8.93 sits exactly in that region. That the borax here is the alkali is not an ILFORD statement, but it is as close to undisputed as an inference in this library gets, and the concentration band the sheet prints — under 8.5 per cent of the large bag — is consistent with an alkali present in grams rather than tens of grams.

What is in the table and what is not

Six components, and no restrainer among them. Read the table for what it is: the substances HARMAN was obliged to name in order to classify two bags of powder. It is not a list of what is in MICROPHEN. It is a list of what is in MICROPHEN and needed saying for hazard purposes, which is a different set, and the difference is invisible from the table itself.

Behaviour

It is faster than ID-11 on every film they share, and the sheet lets you count by how much. This is the least ambiguous thing on the page, because the two developers are printed in adjacent columns of one table at the same meter settings.

Film and meter setting	ID-11 stock	MICROPHEN stock
HP5 Plus, EI 400/27	7 min 30 s	6 min 30 s
HP5 Plus, EI 800/30	10 min 30 s	8 min
HP5 Plus, EI 1600/33	14 min	11 min
HP5 Plus, EI 3200/36	no time published	16 min
DELTA 400, EI 400/27	9 min 30 s	6 min 30 s
DELTA 400, EI 3200/36	19 min	14 min
DELTA 100, EI 100/21	8 min 30 s	6 min 30 s
FP4 Plus, EI 125/22	8 min 30 s	8 min
PAN F Plus, EI 50/18	6 min 30 s	4 min 30 s

All figures at 20 °C from the same table of the same sheet. A shorter time at the same meter setting is not by itself a speed increase — a more energetic developer is also faster — but the last row of the HP5 Plus block is: ILFORD publishes a MICROPHEN time at EI 3200 and leaves ID-11’s cell empty, which is a maker declining to recommend its own product at a setting where it recommends another.

Where the table stops is as informative as where it runs. Six films in it carry a row below their nominal meter setting — DELTA 100 at EI 50, PAN F Plus at EI 25, FP4 Plus at EI 50, HP5 Plus at EI 250 and 320, Kentmere PAN 100 at EI 50 and Kentmere PAN 400 at EI 320 — and MICROPHEN’s cell is empty in every one of them. ILFORD simply does not offer it as a way to rate a film slower. The two DELTA films are the exceptions, and both are films whose nominal setting is already above their measured speed. PERCEPTOL, in the columns to the left, carries no time above a film’s nominal meter setting anywhere in the table. The two products occupy opposite ends of one axis and the sheet draws that axis without ever naming it.

At the far end it is the only powder ILFORD will publish. DELTA 3200 Professional at EI 25000/45 has exactly two published options: the liquid ILFOTEC DD-X at 1+4, and MICROPHEN at stock. That meter setting is twenty-five times the film’s ISO rating of 1000/31 — about four and two-thirds stops.

✕Two HARMAN documents, one film, two different times

DELTA 3200 Professional at EI 25000/45 in MICROPHEN stock is given as 17 minutes 30 seconds by the powder developer sheet, in a table of 20 °C times, and as 22 minutes at 20 °C by the DELTA 3200 film sheet — which prints 17½ minutes as its figure for 24 °C.

The two documents agree exactly at every lower meter setting: 6, 7, 8, 9, 12 and 16½ minutes at EI 400 to EI 12500 in both. They disagree only in the last row, and the powder sheet’s number there is the film sheet’s 24 °C figure sitting in a 20 °C column.

The course does not resolve it. What it does is tell you which way to be wrong: the film’s own sheet is the more specific document and the more recently dated — June 2025 against August 2024 — and 22 minutes at 20 °C is the more conservative choice, since under-development at EI 25000 is not recoverable and over-development by a little is. Take a test frame. And record which sheet you used in the lab notebook, because in a year you will not remember.

It is reusable, and the reuse ladder is arithmetic. Ten films to a litre of stock, with 10 per cent added to the time for each successive film, so the tenth film gets the standard time plus 90 per cent — not 1.1 to the ninth power, which would be plus 136 per cent. ILFORD’s method requires the used developer to be poured back into the stock bottle and mixed with the unused part before the next film, which is a real instruction with a real reason: it re-averages the bromide and by-product concentration across the whole litre instead of letting one film’s worth of restrainer sit in a tank.

And ILFORD tells you not to. The same page that gives the reuse tables says that reuse “lowers image quality slightly and increases the risk of physical damage”, that precipitates may form and emulsion particles stay in suspension, that miscounting is a risk, and that one-shot processing at stock, 1+1 or 1+3 “eliminates or greatly reduces these problems”. It also says flatly: do not push-process in reused developer. Since push-processing is what this developer is for, that is a sharper limit than it looks.

The stock does not keep like a paper developer. Six months full and capped, but only one month half-full — where ILFORD gives its BROMOPHEN paper stock three months in the same condition. A film developer stock with a growing air space above it is a faster-running clock, and the four-months-with-a- floating-lid figure for deep tanks is the same fact stated from the other side.

It is sold in one size. One-litre cartons only, where ID-11 is also sold in five. And the sheet forbids splitting a pack: two bags of unknown relative mass cannot be halved by eye, which is the practical consequence of the composition not being published.

⚗What the published pH actually says, and what it does not

MICROPHEN stock is 8.67 to 8.93. ID-11 stock is 8.60 to 8.70. PERCEPTOL stock is 7.68 to 7.82.

Two observations follow directly, and one popular one does not.

MICROPHEN is not less alkaline than ID-11. It is very slightly more so, and its band is more than twice as wide — 0.26 pH units against 0.10. ILFORD’s phrase “the low alkalinity of the developer reduces grain size and grain clumping” is therefore a claim about this class of developer against speed-increasing developers generally, not a claim about MICROPHEN against ID-11. Reading it the other way is the commonest mistake made with this sentence.

The band is where the family lives. Around pH 8.6 to 8.9, Part VIII’s alkali lesson puts the borax-buffered developer, and the sheet’s own numbers put all three of ILFORD’s powder products in or just below it. A print developer runs nearly two pH units higher, which is the whole reason a print takes a minute and a film takes ten.

What does not follow: any conclusion about composition. A specific gravity of 1.095 against ID-11’s 1.090 says MICROPHEN’s stock carries slightly more dissolved solids than ID-11’s, and that is all it says. It is not a total, it is not a formula, and the course does not turn it into grams.

Use the band as ILFORD asks: measure your own fresh litre with a meter calibrated that day — the calibration procedure is what makes the reading worth anything — and compare every later measurement against your own first one rather than against 8.67 to 8.93.

Image characteristics

Speed: an effective increase, and the word “effective” is doing real work. A developer does not change a film’s ISO speed, which is defined by a fixed development criterion. What it changes is the density obtained at low exposures, so that a usable negative comes back from a higher meter setting. Part XIII puts it precisely: a speed-increasing developer works by developing more of the marginal grains, where a solvent fine-grain developer dissolves some halide before it can be developed and loses speed doing it. ILFORD’s own literature keeps the distinction honestly — DELTA 3200 Professional is rated ISO 1000/31 and sold at EI 3200, and its sheet says the recommended exposure index range “is based on a practical evaluation of film speed and is not based on foot speed, as is the ISO standard”.

Grain: fine, but never finest. ILFORD’s claim is the ratio, not the absolute: a speed increase while “retaining much of the grain characteristics associated with fine grain developers”. The company’s own Finest grain row, on every film sheet in this corpus that has one, names PERCEPTOL and not MICROPHEN. A reader who wants the smallest grain this range can give is being pointed elsewhere by the maker.

Acutance: one sheet claims it and the rest do not. DELTA 3200 Professional’s Maximum sharpness row names MICROPHEN stock. On DELTA 100, DELTA 400, FP4 Plus, PAN F Plus, HP5 Plus and SFX 200 that row goes to a diluted ID-11 or to a liquid concentrate. The most likely explanation is that on a film that grainy nothing else is left to lose, but that is a reading and ILFORD offers no explanation at all.

Contrast: normal, and stated as a number. The times aim at a G-bar of about 0.62, which is a figure you can measure rather than a word you can argue about. If your negatives come back flatter or harder than you want, the sheet’s own instruction is to adjust the time until the contrast is right, and Part XIII’s average-gradient lesson is how to know when it is.

Fog and base density. Not published. ILFORD gives no fog figure for any of the three developers and makes no clean-working claim for MICROPHEN of the sort it makes for its paper developers. Since neither composition table names an antifoggant, this is a place to run your own control rather than to trust a silence. See Experiments.

Image colour does not apply, and neither does staining. This is a conventional silver developer for film; there is no tanning claim, no stain image and no published tone.

The mechanism

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

What the maker states. MICROPHEN is a fine grain film developer giving an effective increase in film speed of up to half a stop with most films and more with the fast ones; it is formulated to avoid the grain increase that usually accompanies a speed increase; its low alkalinity reduces grain size and grain clumping; it has a high speed/grain ratio; its stock runs at pH 8.67 to 8.93 with a specific gravity of 1.095 at 20 °C; it is made from two bags, the smaller dissolved first in warm water; and it is particularly useful for extended development to push fast films.

What follows from the safety data sheets without needing anything else: it is a PQ developer. Part A names 1-phenyl-3-pyrazolidone and hydroquinone on its own product identifier, so the pair is HARMAN’s statement and not a deduction. A pyrazolidone with hydroquinone is the superadditive pair that Part VIII’s superadditivity lesson is built around: the two agents together develop far more than the sum of what each does alone, and the practical signature is exactly what the bands show — a very small quantity of one substance transforming the behaviour of a much larger quantity of another.

Where the course stops, deliberately. The standard modern account of why — that the pyrazolidone does the reducing at the grain surface and the hydroquinone regenerates it out in the solution, so a catalytic quantity suffices — appears in no document in this course’s research corpus, and the superadditivity lesson and the phenidone page both say so. It is not asserted here either. What the sources establish is the shape of the behaviour, not its mechanism.

Inference, labelled as inference: the borate buffer. Part A carries boric acid at 1–5 per cent and part B carries borax at under 8.5 per cent. Borax and boric acid together are a buffer pair — the salt and its conjugate acid — and a buffer pair holds a pH steadier and lower than the salt alone would. Kodak published exactly that construction eighty years ago as D-76d, the buffered borax negative developer, with 8 g of each in a litre against plain D-76’s 2 g of borax and no acid at all. MICROPHEN’s disclosed component list is the only one in this library that matches D-76d’s borate pair. HARMAN says none of this. It does not name an alkali, it does not name a buffer, and it does not say why boric acid is in the bag with the developing agents rather than in the bag with the borax.

Inference, labelled as inference: why part A dissolves first. Sodium metabisulphite dissolves to give bisulfite, a mildly acidic sulfite. Dissolving the two developing agents into a warm, acidic, oxygen-scavenging solution and only then raising the pH with part B is a standard way to keep a hydroquinone from oxidising during mixing, and it is exactly the order ILFORD’s instruction gives. The instruction is HARMAN’s; the reason offered for it is the course’s.

A statement of HARMAN’s that is chemistry and not housekeeping: EUH031. Part A’s label carries “contact with acids liberates toxic gas”. A bisulfite meeting an acid gives sulfur dioxide. That is why the stop bath and the developer must never share a funnel, and it is in Incompatibilities below because it is a real hazard rather than a curiosity.

What is unknown and stays unknown. The ratio of pyrazolidone to hydroquinone. The mass ratio of the two bags. The concentration of the sulfite within a band that runs from 60 to 100 per cent of the larger bag. Whether there is a restrainer at all. The working-solution pH at 1+1 and 1+3. Why this developer gains speed where ID-11, at almost the same pH and apparently in the same family, does not — which is the one question a reader most wants answered and which no document in this corpus addresses.

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

Three faults in these two sheets are worth noticing, because noticing them is part of the skill this course is trying to build.

They run synonyms together. Hydroquinone is printed as “1,4-dihydroxybenzenehydroquinonequinol”: three synonyms concatenated with no separator. A reader who did not already know the substance would struggle to look it up. The CAS number is the field to trust, every time, and it is why every line of the table above carries one.

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

One sheet disagrees with itself about a substance’s hazard. Part A’s section 3.2 marks boric acid “Not classified”; its section 15.1 names the same CAS number as a substance of very high concern restricted as toxic to reproduction category 1B. Both are on the same document. Reconciling them takes knowing how a composition table relates to a classification, and a reader who does not know that will take the wrong one.

The lesson is the same in all three cases: a safety data sheet is a document to read, not a document to trust. Read all sixteen sections, cross-check the CAS numbers, and record what you found.

The nearest open formula

Kodak D-76, and the comparison is the reason this page exists.

D-76 is the archetype fine-grain borax film developer: metol and hydroquinone in a hundred grams of sulfite to the litre with two grams of borax as the alkali, in print since 1928, used at stock strength in a tank or diluted 1:1 as a one-shot. MICROPHEN is the same class of bath — a fine-grain borax developer worked in a spiral tank at 20 °C, reused with a time compensation — arriving as two sealed bags with a pyrazolidone in place of the metol and a speed claim attached.

	Kodak D-76	ILFORD MICROPHEN
Composition	Published in full, twice, twenty-one years apart	Not published, and not even sketched in the technical sheet
Developing pair	Metol 2 g and hydroquinone 5 g per litre	A pyrazolidone and hydroquinone, named only on a hazard sheet, in no stated ratio
Alkali	Borax, 2 g per litre	Borax named, under 8.5 % of the larger bag; boric acid named, 1–5 % of the smaller; loading not published
Preservative and solvent	Sodium sulfite, 100 g per litre	Sodium sulfite named at 60–100 % of the larger bag; quantity not published
Restrainer	None in the formula	None named on either sheet
Published pH	None, in any Kodak printing this course holds	8.67 to 8.93 for the stock; nothing for either dilution
Speed claim	Full film speed, made since the 1920s	An effective increase of up to half a stop, more on fast films
Working dilutions	Stock and 1:1	Stock, 1+1 and 1+3
Reuse	16 sheets of 8 × 10 per gallon, +15 % after every four	10 roll films per litre, +10 % per successive film
Replenished	Yes — D-76R, 120 rolls per gallon with no time increase	No replenisher exists
Keeping, half-full bottle	2 months	1 month
What you can change	Any of four quantities, one at a time	The dilution, the time, the temperature and the agitation

The last row is the whole argument, and it is the same argument every product page in this library makes. Buying MICROPHEN gets you a documented developer with a published pH, a published capacity, a published time for ten films at three dilutions and up to EI 25000, and exactly four variables. Mixing D-76 gets you a bath with no published pH at all and eight variables, four of which are quantities you chose and can move one at a time. Part IX’s developing-agent comparison is the session that makes that trade concrete.

One formula in this library is nearer on composition, and it is not D-76. D-76d, Kodak Limited’s buffered borax negative developer of 1944, is the only open formula here that carries both halves of MICROPHEN’s disclosed borate pair — 8 g of borax and 8 g of boric acid in a litre, beside D-76’s own metol, hydroquinone and sulfite. Four of MICROPHEN’s six disclosed components appear in D-76d against three in D-76. It is named as the nearest match on the component list, and D-76 is named as the nearest formula to use, because D-76d is a variant almost nobody mixes and D-76 is the developer the whole world is measured against — including, in ILFORD’s own sentence, its films’ ISO speeds.

And a caution about the third name in that carton range. ILFORD’s ID-11 is often said to be D-76. This course does not say it. As the D-76 page puts it, ILFORD does not disclose ID-11’s composition either, so the two can be called the same kind of solution and no more. Every ID-11 figure quoted on this page is a published measurement or a published time, never a composition.

Safety

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

The two bags are classified separately and differently. Part A is Acute Tox. 4, Skin Sens. 1B, Eye Dam. 1, Muta. 2, Carc. 2, Aquatic Acute 1 and Aquatic Chronic 1, signal word Danger, pictograms GHS05, GHS08, GHS07 and GHS09, with H302, H317, H318, H341, H351, H410 and the supplemental EUH031. Part B is Repr. 1B, signal word Danger, one pictogram, GHS08, and one statement, H360FD — may damage fertility, may damage the unborn child.

Why B and not C. Level C’s reagent criterion covers carcinogens, mutagens, reproductive toxins and sensitisers “where a fume cupboard or specialist disposal is the recognised control”. HARMAN’s own recognised controls, in section 8 of both sheets, are ventilation or local exhaust ventilation, a washing facility, eye protection to EN ISO 16321-1, impervious gloves to EN 374 and a dust mask or respirator with filter type P where appropriate — not a fume cupboard. The course’s own borax and boric acid pages reach the same conclusion independently and for the same reason: reproductive toxicity keeps these substances out of Level A, and the absence of a fume-cupboard control keeps them out of Level C. Level B, therefore, and the classification rubric is where the criteria are set out.

Why B and not A. Two Level B criteria are met outright: fine powders that must not be inhaled, and a sensitiser handled at high concentration. The dry powder is the whole of the hazard.

⚠The reproductive-toxicity classification, stated plainly

Part B of MICROPHEN is labelled Danger, H360FD: may damage fertility, may damage the unborn child. That is HARMAN’s classification of the bag as sold, not an inference, and it is more serious than anything on part A’s label.

A person who is pregnant, breastfeeding or trying to conceive should not weigh, open, pour or mix these powders. Have somebody else mix the stock; the mixed, diluted, worked solution is a different exposure from a bag of dust, but the powder step is not one to negotiate with. This is the same position the course’s borax page takes for the loose chemical, and buying it in a carton does not change it.

Boric acid, in part A, carries the same class of hazard and is shown in that sheet’s composition table with no hazard codes at all. Do not read an empty cell in a composition table as an absence of hazard.

Personal protection, as the sheets specify it. Eye protection with side protection to EN ISO 16321-1. Impervious gloves to EN 374, with the breakthrough time taken from the glove maker rather than assumed — the glove selection page is where that goes. Protective clothing. A dust mask or dust respirator with filter type P to EN 143 or EN 405 where appropriate, which for tipping two bags of fine powder into a jug is exactly where. Hands and exposed skin washed thoroughly afterwards, contaminated clothing taken off and washed before it is worn again, and — part A’s own precautionary statement — P405, store locked up.

Ventilation and eyewash. Both sheets ask for use with ventilation, local exhaust ventilation or breathing protection, and part A’s asks for a washing facility for eye and skin cleaning to be present. A darkroom with an extractor running and an eyewash bottle within reach meets that; a sealed bathroom does not. Eyewash use is the procedure, and part A is an Eye Dam. 1 material, which means a splash in the eye is a medical emergency and not an inconvenience.

Mix the powder the way the powder deserves. Tip low and slowly into the water, never the water onto the powder; do not dry-mix the two bags together; keep the jug below your face; weighing a solid and mixing a developer are the procedures, and PPE donning and removal is the part people skip.

Published exposure limits, quoted by part A’s sheet from EH40/2005: hydroquinone at 0.5 mg/m³ and disodium disulphite at 5 mg/m³, both as long-term eight-hour limits. Part B’s sheet assigns no occupational exposure limit at all. These are workplace air limits for pure substances and none of them is a limit for a tank of diluted developer; they are here because the sheets print them.

⚠The one line on the technical sheet to disagree with

ILFORD’s technical sheet opens its mixing instructions with: “Photographic chemicals are not hazardous when used correctly.”

The same company’s safety data sheets for the same product classify part A as a skin sensitiser, a suspected mutagen and a suspected carcinogen, classify part B as a reproductive toxicant, put the signal word Danger on both, and instruct the user to store both locked up.

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

Storage

The unopened packets, in their carton, cool and dry at 4 to 20 °C, keep indefinitely — and locked up, which is part A’s own precautionary statement and matters in a house with children or pets. Both sheets record the storage life as “stable under normal conditions” at ambient temperature.

Once a packet is open, ILFORD’s instruction is to make the stock immediately. There is no part-used-bag option. Two bags of hygroscopic powder in a half-open carton will take up water and cake, and the sheet’s own prohibition on making up fractional quantities means a part-used pack cannot be rescued by mixing a smaller volume.

The stock solution goes in a full, tightly capped bottle and keeps six months there. Half full it keeps one month, which is the figure to plan around: a litre of stock in a litre bottle is a six-month reagent, and the same litre decanted into a two-litre bottle is a one-month one. The mechanism is the air space, and the fix is to bottle the litre in several small bottles rather than one big one — the course’s reading, not ILFORD’s instruction, and it costs nothing to test.

A deep tank keeps the stock four months with a floating lid and one month without. That is the same fact about oxygen stated in tank terms and it is the strongest argument for the lid.

Diluted 1+1 or 1+3 is not stored at all — 24 hours is the outside figure, given as a concession rather than a plan. Mix it directly before it is needed, as the sheet says, and pour it away afterwards.

Label everything with the product, the dilution, the date mixed and the film count, using the labelling SOP. A reused stock bottle without a tally on it has lost the one number the reuse scheme depends on, and an unlabelled or undated container is the failure that costs a film you cannot re-shoot. Stock check and storage rotation are how a shelf stays honest.

Incompatibilities

Acid, and specifically the stop bath — and this one is on the label. Part A carries EUH031, contact with acids liberates toxic gas. The metabisulphite in it will give sulfur dioxide when it meets an acid. Never tip stop bath into a developer bottle, never share a funnel or a graduate between the two without washing it, and never store the two powders where a spilt acid could reach them. Part X’s account of why stopping works is the process reason for keeping them apart; this is the hazard reason.

Fixer, in both directions. Thiosulfate carried back into a developer dissolves silver halide and fogs; developer carried into the fixer shortens its life and stains. Part XI covers the process side. It is also a waste problem, because mixing spent developer into spent fixer spoils a solution that would otherwise go for silver recovery.

Strong oxidisers, and dry powder makes it worse. A bleach or a persulfate reaching a bottle of developer is one problem; reaching an open bag of hydroquinone and pyrazolidone is a larger one, because a solid oxidiser meeting a solid reducing agent has no solvent to carry the heat away. Keep the cartons on a different shelf from anything that bleaches, and read the incompatibilities page for the pairs and the reactions.

Air, during agitation. ILFORD’s own instruction for gas-burst agitation is that nitrogen must be used for the developer and air only for the stop bath, fixer and wash. That is the sulfite-preservation argument stated as an equipment rule.

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

Section 10.5 of both MICROPHEN sheets gives incompatible materials as “Not known”, and section 7.2 gives them as “None known” — on the same document whose section 2 carries EUH031, contact with acids liberates toxic gas.

Read literally, section 10 says a bag of metabisulphite has no chemical incompatibilities, which its own label contradicts two pages earlier. A safety data sheet answers a narrow question — what makes this product itself unstable — and it answers it about the product in its container, not about the tank sequence it will be used in. The course’s own incompatibilities page governs here, and the label statement outranks the section-10 boilerplate.

Waste

Bottled separately, and never mixed into the fixer. Spent film developer from MICROPHEN is weakly alkaline, carries the oxidation products of two developing agents, and carries whatever silver the film released in the form of halide rather than recoverable metal. Part A’s classification is Aquatic Acute 1 and Aquatic Chronic 1 — very toxic to aquatic life with long lasting effects — which is principally the hydroquinone; the phenidone page notes that a PQ developer’s waste is dominated by the hydroquinone and the alkali rather than by the fraction of a gram of pyrazolidone in it. Part B’s sheet, by contrast, records low toxicity to invertebrates, fish and algae.

What the sheets say to do with it: dispose of contents in accordance with local, state or national legislation, send to a licensed recycler, reclaimer or incinerator, or take it to a hazardous or special waste collection point. Part A’s section 6 adds that spillages or uncontrolled discharges into watercourses must be alerted to the appropriate regulatory body, which is a strong hint about the drain.

What ILFORD tells United Kingdom domestic users on its own health and safety page: local authorities generally accept small quantities of chemical waste at Household Waste and Recycling Centres, usually in a “chemical cupboard”; chemicals should be bottled separately and appropriately labelled; and a few authorities collect on request. The same page says that where no such route exists, small amounts may be flushed away with plenty of water, that chemicals must not be mixed for disposal, and that septic tanks should be avoided. That last concession is ILFORD’s and not this course’s, and it is written for the United Kingdom.

The disposal caveat governs and local regulation decides. The general chemical waste SOP is the procedure this course follows, and Part XII’s waste-stream lesson explains why the developer bottle and the fixer bottle stay separate: one of them is worth money at a refiner and the other is not.

And the empty packets. They held a Repr. 1B powder and a sensitiser. Do not reuse them for anything, and do not shake them out over a bin.

Troubleshooting

Thin, flat negatives from a stock bottle that has done a few films. Almost always the tally rather than the developer. Ten films to the litre is the capacity and 10 per cent per film is the compensation; skip the compensation and the fifth film is developed at 40 per cent less than the time it needed. See thin negative and flat negative, and put a tally mark on the bottle before you put the film in the tank.

Shadows empty at a pushed meter setting. This is the failure mode this developer exists to postpone and it is not a fault in the bath. A speed increase moves the toe, it does not invent exposure; ILFORD says its own EI ranges are “a practical evaluation of film speed” and not foot speed. Empty shadows and Part XIII’s characteristic curve are where that is diagnosed properly.

Grey base and lifted fog, especially on a pushed film. Neither composition table names an antifoggant, and extended development at high meter settings is the condition that raises fog. Chemical fog, base fog and elevated fog on a curve tell the causes apart, and the test is a clipped, unexposed end of the same film developed alongside.

The stock has gone yellow or brown in the bottle. Oxidation, which is what oxidised developer covers. A half-full bottle past its one-month life should be treated as suspect and tested against a control strip before a film you care about goes in it — control strip processing and charting is how.

Powder that will not all dissolve. ILFORD says explicitly that it is normal for a few grains to remain undissolved and that darker particles in the white powder are normal. A large undissolved residue is different, and points at water that was too cold, part B added before part A had dissolved, or a packet that had been open. Do not filter and use it — see stock crystallised in cold storage for the related fault and its test.

Uneven development, streaks and mottle, especially at short times. PAN F Plus at EI 50 is four and a half minutes at stock, and ILFORD warns that very short development times with some films lead to uneven processing. The sheet’s own escape is in the next column: 1+1 takes six minutes and 1+3 takes eleven, for the same meter setting and the same negative. Mottled development, surge marks and bromide drag are the three patterns and they are told apart by where they appear.

Negatives that do not match the negatives from last month. Check, in order: the dilution — six and a half minutes at stock is twenty-three at 1+3, and a misread dilution ratio is the commonest cause; the film count on the bottle; the temperature; the date the stock was mixed; and which ILFORD document you took the time from, because on DELTA 3200 at EI 25000 two of them disagree.

A whole film blank or nearly blank. Not the developer. Work through Part IX’s fault diagnosis, which separates a chemistry failure from a camera, a loading or a shutter failure before anything gets blamed.

Experiments

Measure the pH of a fresh litre of stock and compare it with ILFORD’s band. The cheapest possible calibration of your own meter, your own water and your own mixing, and the one ILFORD explicitly asks for. Calibrate the meter the same day — the calibration procedure is the whole experiment’s validity — and record the figure. Every later measurement is compared against your own first one, not against 8.67 to 8.93.

Check the specific-gravity table with a hydrometer. Measure stock, 1+1 and 1+3. The prediction is that the density excess over water halves and then quarters: from 1.095 you should read about 1.048 and about 1.024, and ILFORD prints 1.050 and 1.024. If your stock reads well away from 1.095, you have found a mixing error before you have found it on a negative.

The comparison this whole page is about: MICROPHEN against D-76 you mixed yourself. One film, one subject, a step wedge in the corner of every frame. Develop half the roll in MICROPHEN stock at ILFORD’s time for your meter setting and half in D-76 stock, at 20 °C, with the same agitation. Plot both. Part XIII’s step wedge series sets the exposures up and curve plotting is the sheet to record them on. The prediction from ILFORD’s claim is that the MICROPHEN curve is displaced left at the toe by about half a stop with a similar gradient. Measuring your own displacement is the only honest way to know what half a stop means on your film.

Test the reuse ladder instead of trusting it. Take a litre of stock and put ten films through it, one at a time, each with an identical step wedge exposure, applying ILFORD’s 10 per cent per film. If the compensation is right, the ten wedges match. Where they start to drift is your capacity, not ILFORD’s, and it is worth more than the published number.

Run the boundary the sheet will not. Six films in the table carry a row below their nominal meter setting and MICROPHEN’s cell is empty in all six. Take FP4 Plus at EI 50 — a setting ILFORD gives for PERCEPTOL and ID-11 and not for this developer — and find the time yourself. Either you will confirm that a speed-increasing developer has nothing to offer a film you are already over-exposing, or you will find a combination the maker never bothered to print.

Settle the EI 25000 disagreement on your own film. Two HARMAN documents give 17½ and 22 minutes for DELTA 3200 at 20 °C. Shoot one roll, cut it in three in the dark, and develop the pieces at 17½, 20 and 22 minutes. This is a genuinely open question with a two-hour answer, and the result belongs in your lab notebook with both document dates recorded beside it.

Mix D-76d alongside D-76 and see what a borate buffer buys. MICROPHEN’s two sheets disclose borax and boric acid; D-76d publishes both quantities and D-76 publishes neither acid nor much salt. Develop matched films in all three baths, then re-develop matched films in the same three baths after each has done five films. Part IX’s experimental design page is how to run that without fooling yourself, and the interest is entirely in the second half: a buffer’s job is not to change the first film, it is to keep the fifth the same as the first.

Record every bought bath in the version record. A product gets a line in the formula version record too — the carton, the date the stock was mixed, the dilution, the film number in the sequence and the document you took the time from. Those five are the only variables you have, and they are enough to explain almost every result you will get.