Kodak D-165

Take D-72, remove the hydroquinone entirely, double the metol and halve the alkali, and you have Kodak’s low-contrast developer. It is the most instructive formula in the paper library for exactly that reason: everything the second agent was doing shows up as an absence.

Ingredient	Quantity	Form the source specifies
Metol	6.0 g	Kodak calls it Elon
Sodium sulfite	25.0 g	anhydrous — or 50.0 g crystalline
Sodium carbonate	37.0 g	anhydrous — or 100.0 g of the crystals
Potassium bromide	1.0 g	or 10 mL of a 10 per cent solution
Water to make	1000 mL

Purpose

To develop a material whose own contrast is already high — a lantern plate, a photogravure transparency, a contact-speed plate — without adding any of its own. Kodak’s header reads “Elon low-contrast developer for P.300 plates, photogravure transparencies, lantern plates and bromide papers”, and the low contrast is the product rather than a side effect.

Recommended uses

At 1:3 for everything the handbook lists. P.300 plates, four to six minutes at 18 °C. B.40, three minutes. Bromide paper, two minutes. One dilution, three times, and the differences between them belong to the materials.

A low-contrast paper developer earns its place in two situations. The first is a negative that is already too contrasty for the softest paper you have. The second is a material with a naturally short scale, which is most of what Kodak lists here — a lantern plate is meant to be projected, and a photogravure transparency is an intermediate that must not add contrast of its own.

When another formula is preferable

• For normal print contrast, D-72 at the dilution matching the paper.
• For normal to high contrast and a long dish life, D-163.
• For a cold tone on chloride paper, D-158.
• For a warm tone, D-156, which reaches its low working alkalinity by a different route and gets colour rather than softness for it.
• On film, the same idea already exists as D-23, a metol-and-sulfite developer with no alkali at all, and reading the two together shows how far the single-agent idea can be pushed.

Mixing

Dissolve in the order printed. Kodak Limited’s rule: the Elon goes first because it is readily soluble in warm water but only slightly soluble in a sulfite solution with no alkali in it; the preservative follows; the alkali last. The bromide has no action on the agent and may go in at any stage.

1. Dissolve the metol completely, in warm water. At 6.0 g/L this is the largest metol dose in the paper library and the one most likely to be hurried.
2. Add the sodium sulfite.
3. Add the sodium carbonate.
4. Add the potassium bromide, or 10 mL of a 10 per cent stock.
5. Make up to 1000 mL, and dilute 1 part in 4 for use.

The handbook prints both salts twice — 50.0 g crystalline sulfite or 25.0 g anhydrous, 100.0 g crystalline carbonate or 37.0 g anhydrous — and warns in capitals that its avoirdupois and metric columns are not exact equivalents. Use one system throughout.

⚗Why the alkali could come down when the hydroquinone went out

The carbonate here is 37 g/L against D-72’s 67.5, and that is not a coincidence of the recipe. The 1928 primer states the rule directly: developers of higher reduction potential, which bring the image up very quickly, require less alkali than those of lower potential, and hydroquinone in particular “has so low a potential that it is rarely used alone but is generally used with Elon”.

Metol has the highest reduction potential of the agents Kodak ranked. A metol-only developer therefore needs only enough alkali to run metol, and every gram of carbonate beyond that would buy fog rather than speed. Half the alkali of a metol–hydroquinone formula is what a metol-only formula is for.

Behaviour

It comes up fast and then stops climbing. That is the single-agent signature, and the 1928 primer describes it in one sentence: an Elon image “comes up very quickly and gains density slowly”, while a hydroquinone image “comes up very slowly but gains density steadily and rapidly”. Remove the hydroquinone and you remove the steady, rapid density gain — which is to say, the contrast.

Nothing is published about its life. The 1949 keeping-properties and useful-life table has a row for almost every formula in the handbook and no row for this one, so there is no dish life, no bottle life and no sheet count to quote. The course does not supply one. If you need those numbers, they are measurable: put prints through a measured litre and record where the maximum black starts to fall short, and record the result in the lab notebook as your own figure for your own paper.

It is a stock solution used at 1:3, so the working bath carries about 1.5 g/L of metol and 9.3 g/L of carbonate. That is a gentle bath by any measure in this library.

Image characteristics

Contrast. Low. It is the handbook’s own word and the whole point of the formula.

Tonality. Long and gentle, with density accumulating evenly across the scale rather than piling into the highlights. A print in this developer will look flat next to one from D-72, and on a hard negative it will look right.

Colour. Not stated by the source, and the course does not guess. The two levers that Kodak’s own warm-tone formulas move — low alkali and high bromide — are only half present here: the alkali is lowish and the bromide is not raised, so there is no reason to expect the warmth of D-156 and no published claim either way.

Staining. None. Grain, acutance and speed are not meaningful properties of a paper developer, and where this formula is used on plates the handbook publishes no claim about them.

The mechanism

6.0 g/L ÷ 344.38 g/mol = 0.0174 mol/L

Metol, as the hemisulfate

37.0 g/L ÷ 105.99 g/mol = 0.349 mol/L

Sodium carbonate

25.0 g/L ÷ 126.05 g/mol = 0.198 mol/L

Sodium sulfite

1.0 g/L ÷ 119.00 g/mol = 0.0084 mol/L

Potassium bromide

One agent means no superadditivity, and no superadditivity means no reserve. In a metol–hydroquinone formula the two agents together develop faster than the sum of their separate contributions, and the hydroquinone is what keeps the bath going as the metol is consumed — Part VIII covers the effect. Take it away and what remains is a bath whose activity is exactly its metol content, falling as that metol is used. Kodak’s answer is to put in nearly twice as much metol as D-72 carries.

Low contrast is the absence of the density-building agent, not the presence of a softening one. This is worth stating plainly because the alternative story — that something here is holding the development back — is wrong and leads to the wrong adjustments. There is no extra restrainer: 1.0 g/L of bromide is modest, and metol is the agent bromide affects least, so what little there is does comparatively little. The contrast is low because nothing in the bath is building density steadily and rapidly once the image is up.

Which means the time is not a contrast control here either. Extending development in a metol-only bath adds density slowly and evenly and does not restore the highlight separation the hydroquinone would have built. If you need more contrast, you need a different developer or a different paper grade, and this formula’s honest position is that it will not give you one.

Function of every ingredient

Metol, 6.0 g. The only developing agent, at nearly twice D-72’s dose because there is nothing else to help it. It has the highest reduction potential of the agents Kodak ranked, which means it starts development in the thinly exposed regions and brings the whole image up at once, and that it keeps working against accumulated bromide and in a cool bath better than any other agent here. What it does not do is build density steadily and rapidly once the image is up, which is why this formula is a low-contrast one. More metol raises activity and shadow density and eventually fog; less and the bath becomes slow across the whole scale rather than softer. It is a skin sensitiser, and at 6.0 g/L this stock carries more of it than anything else in the paper library — which is what sets this page’s safety level.

Sodium sulfite, anhydrous, 25.0 g. The preservative, and here it is protecting a solo performer. It scavenges dissolved oxygen and intercepts oxidised metol before it forms coloured products; in a two-agent developer a partly oxidised bath still has the second agent to fall back on, and in this one it has nothing. It also carries the bath’s acid reserve into the stop bath. More sulfite keeps better and begins to dissolve silver; less and the bath discolours within a session.

Sodium carbonate, anhydrous, 37.0 g (or 100.0 g of the crystals). The alkali, at about half D-72’s dose, for the reason given above: a high-reduction-potential agent needs less of it. It sets the pH at which metol reduces silver and supplies a carbonate–bicarbonate buffer to hold it there as the agent releases acid. More carbonate speeds the bath and raises fog without raising contrast, which is the worst trade available here; less and the times become impractical.

Potassium bromide, 1.0 g. The restrainer, kept modest deliberately. Bromide acts far more strongly on hydroquinone than on metol, and this bath has no hydroquinone at all, so a large dose would buy much less than it does in a metol–hydroquinone formula and would cost shadow speed in a developer already working gently. One gram is enough to keep the whites of a print clean under a safelight. More bromide cleans further and slows the bath without adding contrast; less fogs.

Water to 1000 mL. Not inert. Iron is the classic contaminant, and a stock that has crystallised in the cold is warmed and redissolved rather than decanted — the handbook’s note is that the precipitate often contains the most important constituents of the solution.

Interactions

Agent and alkali. The clearest instance in the formulary of the 1928 primer’s rule that the required alkali follows the agent’s reduction potential. Compare the four Kodak print formulas: the metol-only one needs 37 g/L, the metol–hydroquinone ones need 65 to 69 g/L, and the warm-tone ones deliberately fall below that to slow the whole reaction down.

Agent and agent. There is none, and that absence is the subject of the page. Everything Part VIII says about superadditivity applies to this formula only as a description of what it is missing.

Agent and restrainer. Weak, by construction. Metol is the agent bromide affects least, so this is the formula in the library where adding bromide changes the least. That makes it a useful control in a bromide series: if a change you attribute to bromide shows up here as strongly as in D-158, the change was not the bromide.

Agent and sulfite. At 0.198 mol/L the sulfite is a preservative and an acid reserve. It is well below the concentration at which sulfite acts as a silver solvent, which is right for a paper developer.

Variants

Nothing in the corpus modifies this formula, and the handbook does not mark it as available as a packed powder — one of the few paper formulas it does not. Where a low-contrast developer is wanted for a modern variable-contrast paper the sensible route is a lower filtration grade rather than a softer developer, because the paper offers a wider range than the chemistry can.

On film, the same principle appears as D-23, metol and sulfite with no alkali at all. Reading the two together shows the single-agent idea taken to its two ends: D-165 keeps an alkali and is a low-contrast print developer; D-23 abandons the alkali and is a fine-grain film developer.

The course’s own variants belong in the formula version record.

Safety

Level B, and unusually for this library the reason is metol alone. Metol is a skin sensitiser, sensitisation is permanent, and this stock carries 6.0 g/L of it — the largest dose of the paper formulas here. There is no hydroquinone on the page at all, which removes the suspected carcinogen and mutagen from the list and is worth noticing: this is a formula whose hazard profile is genuinely narrower than its neighbours’, and narrower in a way that matters if hydroquinone is your concern. It is emphatically not narrower if metol is.

Sodium carbonate at 37 g/L is an eye hazard in the stock.

Weigh the metol with care. It is the operation with the highest exposure on this page: a fine powder, a sensitiser, and twice the usual quantity. Extraction running or an enclosure, never a draught, splash goggles on. In the tray, print tongs — one pair, never interchanged — and gloves if your hands go in. The classification rubric sets what Level B assumes and the gloves page covers the choice.

If metol is the problem, D-173 is Kodak’s own metol-free paper developer, published for exactly that reason. It is not a low-contrast formula, so the substitution is not free.

Storage

No keeping figures are published for this formula, so the sensible practice is the library’s general one: stock in a tightly closed bottle filled as full as it will go, in several small bottles rather than one large one, and working solution mixed for the session. Label everything with the formula, the dilution and the date, per the labelling SOP.

Treat a brown or amber stock as suspect and test it against a control print before using it on anything that matters. With a single developing agent there is no second agent to carry a partly oxidised bath, so the colour is a more direct warning here than it is elsewhere.

Incompatibilities

Acid, deliberately, in the next tray. A splash of stop bath drops the pH below the region where metol works and there is no second agent to continue. Tongs never travel backwards along the sequence.

Fixer, in either direction. Thiosulfate carried back into a developer fogs and stains; developer carried forward raises the fixer’s pH, with the white sludge and brown-staining prints the 1928 primer describes.

Oxidising agents — ferricyanide, permanganate, persulfate — never meet a developing agent in a bottle or a drain. See chemical incompatibilities.

Waste

A dilute alkaline solution whose environmental load is the metol, which carries an aquatic-toxicity classification, and which is present here in larger quantity than in any other formula on this shelf. It carries essentially no silver and belongs in its own labelled container, never in the fixer bottle. The disposal caveat governs and the general chemical waste SOP gives the procedure. Local regulation decides.

Troubleshooting

Prints that look flat. The formula working correctly. If they look flat and you did not want low contrast, you have chosen the wrong developer, and no adjustment of time will fix it.

Prints that never quite reach black. Extend the time first, because a single-agent bath adds density slowly and the published two minutes for bromide paper is a minimum. If a much longer time still will not do it, the bath is exhausted — and with no published capacity to check against, that is a judgement you make from a control print.

A bath that dies faster than expected. Expected, in fact: there is no hydroquinone reserve here. The activity of this developer is its metol content, falling as the metol is consumed.

A brown stock solution. Oxidised metol, and more serious here than elsewhere for the same reason.

Fog on a paper that is clean in other developers. Check the bromide. At 1.0 g/L this is the second-lowest restrainer dose in the library, and a bath mixed without it is a bath with no antifoggant at all.

Experiments

Add the hydroquinone back, one step at a time. Mix this formula as published, then again with 3 g/L, 6 g/L and 12 g/L of hydroquinone added and nothing else changed. Print one negative on one paper in all four, matching density by exposure. You are measuring what the second agent contributes, and the prediction from the mechanism above is that contrast and maximum black rise while the time to first appearance barely moves. Record it against the developer laboratory report.

Use it as the control in a bromide series. Because metol is the agent bromide affects least, adding bromide to this bath should do far less than adding the same bromide to D-158. Run both and compare the sizes of the two effects. This is the one-variable discipline of Part IX applied to a claim from 1928.

Find the capacity Kodak did not publish. Put prints through a measured litre of working solution, keeping one print in five, until maximum black falls short of a fresh-bath reference. The output is a number for your paper and your session, and a demonstration of why a manufacturer might have declined to print one.

Measure the alkali claim. Mix the formula at 37, 55 and 67.5 g/L of carbonate. The 1928 primer predicts a faster bath with more fog rather than more contrast. If contrast rises noticeably, the primer’s rule is incomplete for this case and you have something worth writing down.