Break/Fix: The Print That Will Not Go Black

Part XVI’s break/fix page ends with a boundary and three results that cross it: an unexposed sheet from a fresh, unopened packet that also comes out grey; blacks that are dull with no fog anywhere; and whites that are stained rather than veiled. It names this page as where they go, and this page begins by accepting them.

The one-sentence test for which page you are on has not changed. If your whites are the problem, you are in Part XVI. If your blacks are the problem and the whites are clean, you are here. Tonight both are wrong at once, which is why the evening is worth ninety minutes.

The situation

It is a Tuesday in November. You printed happily in October on the same box of paper, in the same room, with the same enlarger, and you have the printing maps from that session to prove it.

Tonight, nothing is right. The blacks are a dark grey. The whites are not white — but only, as far as you can tell, inside the picture; the margins under the easel blades look better than the sky does. Every print takes longer to come up than you remember. And on the last three or four sheets, drying on the rack, there is a faint yellow discolouration along the borders that was not there when they went on.

The developer was mixed on Sunday and has been in the tray since, with a sheet of card over it. You have put perhaps thirty 8 × 10 sheets through it in two sessions. The fixer is the one you made three weeks ago. You did not take the temperature tonight, because the room feels the same as it always does.

There are at least three faults in that paragraph and possibly only one. The temptation — mix everything fresh, open a new box, and print again — would probably work, and would teach you nothing, and would leave you with no idea which of tonight’s three habits to change. Every change you make before you collect evidence destroys evidence.

Before you start

Level A, and it is the ordinary tray sequence: gloves, eye protection, a through draught, four dishes with a pair of tongs each, spent fixer and first wash into silver-bearing waste. Nothing is weighed and no concentrate is decanted.

Two things about this session are worth stating, because they are peculiar to a diagnostic evening.

You will handle faulted solutions at length. An exhausted developer, an over-diluted one and a bath that has stood for four days are the same chemistry as a fresh bath — the hazard statements on metol and hydroquinone do not soften because a bath is tired — but you will be pouring them between vessels, holding them up to the light, and working with your hands in them for longer than a printing session requires. Gloves on for the whole evening, labelled containers for everything you pour out, and nothing goes back into a stock bottle. A contaminated or exhausted solution returned to stock turns one bad session into a bad month.

The deliberately exhausted fixer is still silver-bearing, and more so than a fresh one: exhaustion is what “full of dissolved silver” means. It goes to the silver stream like the rest, and the disposal caveat governs.

Alternative route

Without a densitometer, the entire page works. Every discriminator here is a pattern — where the grey is, whether the borders match the picture area, whether a stain appeared before or after drying, whether a second sheet from a different box behaves differently — and patterns are read by laying two prints side by side in even light. What you lose is the ability to say how much, which matters for the record and not for the diagnosis.

Without a fresh, unopened packet of paper, the second control is unavailable and the differential loses its floor, exactly as it does in Part XVI. Anything from a genuinely different box will serve provided you write down what it was. What you cannot do is skip the control and reason as though you had it.

Without a fixer clearing test, you are missing the one measurement that arrives before the damage. The test needs a scrap of undeveloped film, not paper, and if you have no film at all then the honest fallback is to treat the fixer as suspect, mix a fresh bath, and settle the question by substitution rather than by measurement — recording that you did it that way.

Without a darkroom there is no route to this page. The faults are diagnosed by making prints, and a print needs a dark room. What a reader without one can take from it is the differential itself, which is worth reading before the evening it is needed rather than during it.

The symptoms

Describe what you see before you name it. The words are not interchangeable, and each pair below points at a different half of the chemistry. Do this with the prints dry, in even daylight, beside a print from October.

Say this	Not this	Because
The black is dull — dark, but grey-dark, and the print looks heavy	The black is thin — light, and the print looks under-exposed	A dull black reached the paper and stopped short of the ceiling. A thin black never got there. One is a development question, the other an exposure question
The white is grey overall, margins included	The white is grey only inside the exposed area	Grey under the easel blades means something reached the paper that the blades did not mask — fog or chemistry. Grey only in the picture is an exposure or a flare question
The stain is warm yellow, at the borders, and appeared as the print dried	The stain is brown or uneven, and was there wet	A yellow that arrives with drying is residual chemistry. A brown that was there wet is usually oxidation products from the developer
The image took longer than usual to appear	The image appeared at the usual moment and then stopped	Emergence time is the earliest and cheapest signal that a bath is dying, which is why it belongs on every printing map

Four sheets, four different faults, and the one place to look first on each

1. 1Dull black, clean whites — development did not finish, or the bath is weak — the black end alone is short
2. 2Both ends grey, slow emergence — the whole scale has moved inwards: a bath that has done its work
3. 3Even veil including the masked border — not the enlarger. Chemistry or the material — and Part XVI if a fresh packet is clean
4. 4Warm yellow at the borders, arriving on drying — residual silver from a fixer past its capacity

Evidence to collect

Seven items. Five cost nothing but a sheet of paper, and none of them involves changing anything.

Evidence	How to get it	What it establishes
Control 1: an unexposed sheet from the packet you are printing from	In the dark, straight into the developer, processed normally with nothing else in the tray	The base plus fog of the paper you are actually using, after everything your room and your chemistry have done to it
Control 2: an unexposed sheet from a fresh, unopened packet	Open a new packet in the dark; one sheet, same bath, same time, same session	The paper’s base before your box was opened. The difference between the two controls is the whole of the paper’s contribution
The double-time print	One more print at tonight’s exposure, developed for twice the time, everything else identical	Whether the developer can still reach the black. This one sheet settles more than any other item on the list
The developer’s own history	The label and the log: mixing date, dilution, temperature tonight, sheets already through it, hours standing in an open dish	Whether the bath is inside its published capacity and its published life, both of which are numbers rather than judgements
The fixer’s clearing time	A scrap of undeveloped film, timed to clear, against the figure from when the bath was fresh	Whether the fixer is exhausted. Appearance is not evidence: a used bath may look entirely unremarkable
The wash record	The route and its time, from the session log	Whether a stain is a fixing failure or a washing failure, which are different faults with different fixes
A print from October	The archive box	The reference. Every “worse than” on this page needs a “than what”

!Why the two unexposed sheets come first, and what each outcome means

Part XVI built its differential on these two sheets and this page inherits them, because between them they separate the three things that can grey a white before you have spent a penny.

• Both clean, matching the paper’s normal base. The paper and the developer are both excluded. If your whites are still grey on a print, the fault is in the room or the equipment and it belongs back in Part XVI.
• Both grey, equally. The paper is excluded and the developer is not — the only thing that acted on a sheet that was never exposed is the chemistry. Go to developer fog on paper and to the developer differential below.
• Control 1 grey, control 2 clean. The developer is excluded, because it treated both sheets the same way. The box you have been printing from has been fogged in store, and paper storage fog is the entry.

Two sheets. Three outcomes. No instrument.

Hints, in increasing order of disruption

Work down. Stop at the first one that changes the result, and write down where you stopped — the position in this list is itself a diagnosis.

1. Put the thermometer in the developer. Free, ten seconds, and it is the single commonest cause of “the paper has changed”. The maker’s recommendation is 20 °C ± 1 °C, with the note that a slightly lower temperature needs the development extended slightly. A November room can sit at 16 °C without feeling cold, and a bath four degrees down develops visibly less in the same time.
2. Read the developer’s label and your log. Mixing date, dilution, and the number of sheets through it against the published capacity — for the concentrate at 1+9 that is 100 resin-coated or 50 fibre-base 8 × 10 prints per litre, and about half that if the paper is a cool-tone one. Thirty sheets through a litre is fine; thirty through 500 mL, twice, is not.
3. Ask how long the bath has been standing. The maker states that a working-strength paper developer left in an open dish should not be kept for more than one working day, and that a tightly capped bottle buys about twenty-four hours. Kodak give D-72 the same twenty-four hours standing in a dish against three months in a full stoppered bottle. A tray covered with card since Sunday is four times past that.
4. Make the double-time print. One sheet, twice the development, everything else held. This is the hinge of the whole page and the section below is written around it.
5. Run the clearing-time test on the fixer. A scrap of undeveloped film and a clock.
6. Open a fresh packet of paper for control 2, if you have not already.
7. Mix one fresh bath — the developer — and change nothing else. Substitution is a legitimate test and it is the first genuinely disruptive one, because it destroys the evidence in the tray.
8. Mix everything fresh. This usually cures the session and proves nothing. It is where you go when the seven items above have not converged, and the price is that you will meet the same evening again in February.

The diagnosis

From the symptom you can describe to the one test that discriminates

1. 1Which end of the scale is wrong? — the question the symptoms table exists to let you answer
2. 2Two unexposed sheets — separates room, developer and paper before you spend anything
3. 3One double-time print — separates slow, fogging and finished in a single sheet
4. 4One clearing time — the only fixer measurement that arrives before the damage
5. 5The faint box is not this page — a clean pair of controls with a veil still present sends the case back to Part XVI

The double-time print, which settles the developer question in one sheet

Give one print twice tonight’s development time at tonight’s temperature, in tonight’s bath, at tonight’s exposure. There are three outcomes and each excludes something.

• The blacks come good and the whites stay clean. The bath is slow rather than finished. It has activity left and tonight’s time was not enough for it — which points at temperature, at dilution, or at a bath that has aged enough to need longer but not enough to fail. The fix is a fresh bath and a thermometer, not a new box of paper.
• The blacks come good and the whites go grey with them. The bath is fogging. Doubling the time gave the unexposed grains the time they needed too, which is the definition of developer fog on paper: whites lift, blacks stay. Look for a bath that has stood too long, a temperature well above 20 °C, or a restrainer that was never in it.
• Nothing improves. Neither end moves. The bath has done its work and no amount of time will get it back, and the atlas entry is grey highlights from developer exhaustion: the whole scale has moved inwards, which is the signature that distinguishes exhaustion from fog.

⚗Why the double-time print discriminates, when a second ordinary print does not

Paper is developed to completion, and the previous lesson’s plateau is what makes the test work. Development time on paper is not a contrast control: it is a run-up to a ceiling. So a healthy bath given twice the time produces almost exactly the same print — the maker publishes that development may be extended to six minutes with no noticeable change in contrast or fog — while a slow bath given twice the time produces a better one, because the extra time is being spent climbing rather than sitting at the top.

That asymmetry is the whole of the test. A bath’s remaining activity is invisible in a single print at the normal time and obvious in a pair of prints at one and two times it.

The developer differential

Six ways a paper developer disappoints, and what separates them.

Cause	The signature	The cheapest test
Too cold	Everything slow, everything weak, whites clean; the double-time print is good	The thermometer, before anything else
Too dilute	The same picture as too cold, and the thermometer says otherwise	The mixing arithmetic in the log; and dilution ratio misread is the atlas entry
Too many sheets through it	The whole scale inwards, emergence noticeably slower, tone often warmer — Kodak state that developer contamination or exhaustion causes image-colour variations	The sheet count against the published capacity
Stood too long in an open tray	Amber or brown solution; thin, flat prints; sometimes a base stain that does not wash out	Look at it in white light. Colour convicts and clear does not acquit — the rule the atlas entry states
Fogging	Whites lift, blacks stay black, and the unexposed control is grey	The two control sheets
Contaminated with fixer	Erratic: weak, uneven, sometimes almost nothing. The maker’s instruction is explicit — do not contaminate developer with stop bath or fixer	The tongs. One pair per tray, and ask yourself honestly whether that held on Sunday

The last row deserves its own sentence, because it is the one people talk themselves out of. A pair of tongs that has been in the fixer and then in the developer has put thiosulfate into a bath that has no defence against it. It is why the bench layout on the lab page draws a contamination boundary and gives each developer its own tongs, and it is why the fault is common in exactly the sessions where somebody was tidying up.

Development stopped too soon

Distinct from all six, and the commonest of the lot in a beginner’s darkroom: the print looked too dark in the tray and came out early.

What that gives is not a lighter print. It is an incompletely developed one. The maker’s own words for their resin-coated papers are that prints developed for shorter times “may be underdeveloped and lacking in contrast and density”, and the print that results is heavy in the mid-tones, grey rather than black at the bottom, and often slightly warm. The atlas entry is muddy print from a snatched development and it owns the mechanism.

⁇Whether a snatched print is mottled, or merely weak

The course has looked for a Tier 1 or Tier 2 statement that a snatched print is uneven as well as weak, and has not found one. What the manufacturers state is the weakness: underdeveloped, lacking in contrast and density. Kodak’s toning guide separately states that insufficient agitation in the first few seconds of the stop bath can cause a mottle that only shows after toning, which is a different step and a different fault.

The unevenness claim is therefore the course’s own reading, and its reasoning is stated so you can disagree with it: agitation is never perfectly even in the first thirty seconds, a print pulled at thirty seconds is a print whose development was still visibly in progress, and what is still in progress is by definition not yet uniform. The atlas entry words it as “sometimes there is unevenness with it” rather than as a rule.

How to settle it on your own bench, which is better than either of us arguing: print two sheets at the same exposure, pull one at thirty seconds and give the other its full time, dry both, and look at the pulled one across the sheet rather than at its overall density. If it is uniformly weak, this course is wrong about the mottle and you should write that in your notebook.

The fixer differential

The fixer is where tonight’s stain comes from, and it is a separate fault from the dull black even when they arrive on the same evening.

An exhausted fixer leaves what no wash can remove. Kodak state it plainly: an exhausted fixing bath contains insoluble silver compounds that remain in the print and cannot be completely removed by washing, and those residual silver compounds produce a dark yellow stain, especially noticeable in print borders and highlights. That is the geography of tonight’s stain and it is not a coincidence: the borders and the highlights are where the halide was, so they are where the retained complex is. Kodak’s statement is made in the context of preparing prints for toning, where a toner makes the stain unmissable; the course’s atlas carries the untoned case at residual silver and yellow staining and yellow-brown highlight stain from residual silver, and Parts XI and XII own the chemistry.

Over-fixing is a real fault and it makes the black worse. Both makers say so, and they say different halves of it. ILFORD: there is no benefit in extending fixation, some loss of print quality may be seen from image etching, and long fixing times affect the paper’s image colour. Kodak: prolonged fixing expands the paper and lets the solution into the base, where it is difficult to remove, and prolonged fixing can also reduce the silver image. A weakened silver image is a duller black, so “I left it in the fixer to be safe” is a route to exactly the symptom this page is named for.

A hardening fixer fights everything downstream. ILFORD do not recommend one because it reduces washing efficiency; Kodak do not recommend one for prints that will be toned, because it makes the emulsion less receptive to the toner. If your fixer contains a hardener and you have a yellow stain and a long wash, those facts are related.

And the measurement that arrives before the damage is the clearing time. A used fixer may look slightly yellow, or turbid, or entirely unremarkable — appearance is not evidence, which is why exhausted fixer opens by saying that you often see nothing at all in the bath. Run the clearing-time test on undeveloped film against the figure you recorded when the bath was fresh. For permanence, ILFORD publish a silver-concentration ceiling rather than a sheet count and note that throughput can only ever be a guide: below 2 g/L for a high level of image permanence on fibre paper, which approximates to about forty 8 × 10 prints per litre, and below 0.5 g/L — about ten — for prints needing maximum stability.

📓Stain, veil and milk: three different whites, three different faults

• A veil is a neutral grey over the whole sheet, present when the print was wet, and it is either fog or exhaustion. It lifts the toe.
• A stain is warm yellow or brown, strongest in the borders and highlights, and it usually appears or deepens as the print dries. It is residual chemistry: residual silver from a spent fixer, or residual thiosulfate from a failed wash.
• Milkiness — an opalescence in the clear areas, visible best by reflected light at a low angle — is undissolved halide, which is under-fixing, and it is the one on this list that is often rescuable today by refixing in a fresh bath while the print is still wet.

Which of the three you have decides whether you fix your fixer, your wash or your developer, and they are told apart by looking rather than by testing. Learn the three words.

The paper differential

Three ways the box is the fault.

Age, heat and damp. ILFORD give their resin-coated papers two years in excellent condition when stored as recommended, which is a figure conditional on the storage rather than independent of it, and instruct cool, dry storage away from high temperature and high humidity. Kodak are blunter about the other end: a damp basement causes deterioration of films and papers which can result in weak, mottled pictures. The atlas entry is paper storage fog and it holds the sourcing; what this page adds is that the fault is settled by control 2 and by nothing else, because storage fog and developer fog look identical on a print.

A part-used packet left open. The commonest version of the above and the most avoidable. Return unused paper to its original packaging, every time, which is Kodak’s instruction and takes four seconds.

The wrong side of the sheet. It happens, it happens in the dark, and it produces something no other fault on this page produces: a print that is very weak, very flat, slightly diffuse, and entirely normal in its borders. On a resin-coated sheet the emulsion side is the shinier one and the back carries no gloss; feel the corner rather than guess. If your first suspicion tonight is exhaustion and your prints are far weaker than exhaustion explains, check this before you mix anything.

Dry-down mistaken for a fault

A print judged wet and found dull dry is not a fault at all, and the previous page is what settles it.

You now have a measured number: dry-down for your paper, your developer and your drying method, as a density at a stated tone and as a fraction of a stop. Compare tonight’s disappointment against it. If the difference between what you expected and what you got is about the size of your measured dry-down, you have not got a chemistry problem — you have got a viewing problem, and the fix is to judge dry prints under the light they will be seen in and to apply the correction at the timer.

If the difference is several times your measured dry-down, dry-down is not the explanation and the rest of this page applies. That is the whole value of having measured it: it converts an argument into a comparison.

Where this page stops

This page owns the chemistry and the material. It does not own the room or the equipment, and there are three results that send you back across the boundary.

• An even grey veil that includes the border the easel blades masked, with both control sheets clean. Nothing your chemistry did can produce a veil under a blade on a sheet whose developer treated a fresh sheet cleanly; that is light.
• A gradient: one edge or one corner consistently lighter or greyer than the rest, the same way every time. That is uniformity or a leak.
• A bright patch with a soft edge, shaped like something on the bench. That is an indicator lamp, a timer display or a lamphouse leak.

All three belong to Part XVI’s break/fix page, which has the five fog sources and the eight sources of unevenness and separates each with a test that changes one thing. This page will not repeat them, and the atlas entries — safelight fog, room light leak, enlarger lamphouse or bellows leak — are that page’s rows rather than this one’s.

The fix

For tonight’s evening, worked through in order, the answer is almost certainly three faults and not one, which is the ordinary state of a darkroom that has drifted rather than broken.

1. The developer. It was mixed on Sunday, has stood in an open dish under a sheet of card since, and has had roughly thirty sheets through it. The published life for a working-strength paper developer in an open dish is not more than one working day. Discard it. Mix fresh, at 20 °C, measured with a thermometer rather than with a hand, immediately before use. An exhausted tray is discarded and not extended: there is no replenishment scheme for a tray of paper developer in this course’s corpus, and topping a spent bath up with fresh concentrate gives you a bath of unknown bromide and unknown pH, which is a bath whose behaviour you no longer know.
2. The fixer. Three weeks old, of unknown throughput, and the yellow border stain is its signature. Run the clearing time to confirm rather than assume, then mix fresh and start a capacity log with the first sheet. Then re-fix and re-wash tonight’s stained prints while they are still wet if you want to keep them, following the archival sequence; a dry stained print is a much poorer prospect and the atlas says why.
3. The temperature. Buy nothing. Put the thermometer in the tray at the start of every session and write the number on the printing map. This is the cheapest of the three fixes and the one most likely to be quietly abandoned in March.

And then confirm with one sheet, not with a whole session. Print the same negative at the same exposure in the fresh chemistry, dry it, and lay it beside tonight’s. One print that is right is a confirmation; an evening of prints that are right is a habit, and the two are not the same evidence.

✕The three tests that would have made this evening ten minutes long

Every one of them is free and every one is a line on a record you already keep.

The thermometer in the tray, read and written down before the first sheet.

The emergence time, written down when the bath was fresh. Tonight’s prints “took longer to come up” — but longer than what? The maker publishes about ten seconds for a correctly exposed print in their concentrate at 1+9 on resin-coated paper, and for fibre their two sheets give twenty seconds on one and thirty-five on the other, which is itself a reason to measure rather than to look up. Your own bath’s figure, written on the map on the day you mixed it, is the number that turns a feeling into a measurement.

The sheet count against the published capacity, kept as a running total rather than reconstructed afterwards. Nobody can remember how many prints went through a tray two weekends ago, and everybody believes they can.

What to record

Three records come out of a diagnostic evening, and the last of them is the one people skip.

On the printing map of every sheet you made tonight, the same fields as always — and tonight the two that matter most are the ones you did not have: the developer’s version, mixing date and measured temperature, and the fixer’s identity and running total. A map from a bad evening is as valuable as one from a good evening, and more so if it is the only one of the two you have.

In the session log, one line: the symptom in the vocabulary of the symptoms table, the evidence collected and what each item excluded, the hint at which the result changed, the fault, the fix, and the single test that confirmed it. That last field is the discipline. A session that ends “I changed four things and it got better” has produced no knowledge; a session that ends “the double-time print came good with clean whites, so the bath was slow rather than finished, and a fresh bath at 20 °C confirmed it in one sheet” has produced a rule you will use for years.

In the troubleshooting atlas, if the fault is one the atlas does not carry. The atlas has an entry for each of tonight’s faults already — exhausted developer, oxidised developer, grey highlights from developer exhaustion, developer fog on paper, muddy print from a snatched development, exhausted fixer, under-fixing, residual silver and yellow staining and paper storage fog — and each follows the same six headings: what you see, likely causes, the chemistry and physics, diagnostic questions, corrective action, prevention. Writing one for a fault of your own, in that shape, is the exercise this page sets, and the shape is the point: a fault described without a diagnostic question is a complaint.

Prevention, which is four habits and no equipment

Mix the working developer immediately before the session, which is the maker’s own instruction, and discard it at the end. The bottle keeps; the tray does not.

Keep a running total on the tray and on the fixer, against the published capacity, written as you go. Capacity is a published quantity and exhaustion is a condition you diagnose; the log is what stops you having to diagnose.

One pair of tongs per tray, and never a shortcut. Fixer in the developer is the one fault on this page with no gradual onset and no warning.

Read the thermometer, every session, and write it on the map. Of the three faults in tonight’s story, this is the one that will come back.

Recap

• The boundary first. Whites are Part XVI; blacks with clean whites are here. Tonight had both, which is why it needed a differential rather than a guess.
• Describe before you diagnose. Dull is not thin, an overall grey is not a grey inside the image, and a yellow stain that arrives on drying is not a veil that was there wet.
• Two unexposed sheets separate paper, developer and room before you spend anything, and they are Part XVI’s controls used again rather than a second set.
• The double-time print settles the developer in one sheet. Blacks better and whites clean means slow; both better together means fogging; nothing means finished.
• The published numbers are the ones to check first: 20 °C ± 1 °C; not more than one working day in an open dish; 100 resin-coated or 50 fibre 8 × 10 prints per litre at 1+9. Each is a number, not an opinion.
• The stain is the fixer’s. An exhausted bath leaves insoluble silver compounds that washing cannot remove and that yellow the borders and highlights; over-fixing etches the image and can reduce it; a hardening fixer makes washing and toning worse.
• A snatched print is weak and flat on the makers’ own words; that it is also mottled is this course’s reading, marked as such, and testable on your bench in two sheets.
• Dry-down is not a fault, and now that you have measured it you can say so with a number instead of an argument.
• The record is the deliverable. The fault, the fix, and the one test that confirmed it.

Check your understanding

Question 1. You give one print twice tonight’s development time. The blacks come good and the whites go grey with them. What does that rule in, and what does it rule out?

• A slow bath — it just needed longer, and the session can continue at the longer time
• A fogging bath: the extra time developed the unexposed grains too, which is fog rather than a shortfall of activity — so exhaustion is ruled out and a fresh bath is needed rather than a longer time
• Exhausted fixer, since the whites are affected
• Paper storage fog, since both ends moved

Show the answer and why

Answer: A fogging bath: the extra time developed the unexposed grains too, which is fog rather than a shortfall of activity — so exhaustion is ruled out and a fresh bath is needed rather than a longer time

The three outcomes of the double-time print each exclude something different. A bath with activity left gives better blacks and keeps the whites, because the highlights have no developable silver to gain. A bath that fogs gives the unexposed grains the same extra time, so the whites lift alongside the blacks — the signature the atlas records as whites lift and blacks stay, seen here in its dynamic form. A bath that has done its work moves neither end, because there is nothing left to do the work with. Printing on at the longer time would be printing with a fog you have just demonstrated, so the answer is a fresh bath.

Question 2. A yellow discolouration appears along the borders and in the highlights of prints as they dry. Which bath is implicated, what is the chemistry, and why does washing not fix it?

• The developer: oxidation products stain the base and more washing removes them
• The fixer: an exhausted bath leaves insoluble silver compounds in the print that washing cannot completely remove, and they show most in the borders and highlights because that is where the halide was
• The stop bath: an overconcentrated stop causes a yellow border
• The wash: residual thiosulfate always shows as a border stain first

Show the answer and why

Answer: The fixer: an exhausted bath leaves insoluble silver compounds in the print that washing cannot completely remove, and they show most in the borders and highlights because that is where the halide was

Kodak state the mechanism directly — an exhausted fixing bath contains insoluble silver compounds that remain in prints and cannot be completely removed by washing, and they produce a dark yellow stain especially noticeable in borders and highlights. The geography is the clue and it is not arbitrary: the borders and the highlights carried the most undeveloped halide, so they are where a bath that could no longer form soluble complexes left the insoluble ones behind. A washing failure is a different fault with a different signature and its own atlas entry; the way to tell them apart is the clearing-time test on the fixer, which is a measurement of the bath rather than an inspection of the print.

Question 3. A printer says they leave prints in the fixer for ten minutes "to be safe". What do the manufacturers say happens, and how does it relate to the symptom this page is named for?

• Nothing measurable happens to the print; over-fixing costs nothing but time
• Prolonged fixing expands the paper and drives solution into the base where it is hard to remove, can etch the image, affects image colour, and can reduce the silver image — a reduced silver image is a duller black, so the habit produces the very symptom it was meant to prevent
• It improves permanence at the cost of a longer wash
• It only matters for resin-coated papers, because of edge penetration

Show the answer and why

Answer: Prolonged fixing expands the paper and drives solution into the base where it is hard to remove, can etch the image, affects image colour, and can reduce the silver image — a reduced silver image is a duller black, so the habit produces the very symptom it was meant to prevent

Both makers publish the penalty and they publish different halves of it. ILFORD state there is no benefit in extending fixation and name image etching and a shift in image colour; Kodak state that prolonged fixing expands the paper, lets fixer into the base where it resists removal, and can reduce the silver image. Reduction of the silver image is a direct loss of maximum black, which is why a printer chasing safety by fixing longer can end up with exactly the dull black they were worried about — plus a much harder washing problem, since the answer to doubt about fixing is a fresher bath and a short time, never a longer one.

Question 4. Control 1, an unexposed sheet from your working packet, comes out grey. Control 2, an unexposed sheet from a fresh unopened packet processed in the same bath in the same session, comes out clean. What is established?

• The developer is fogging, since a sheet that was never exposed came out grey
• The developer is excluded, because it treated both sheets identically — the box you have been printing from has been fogged in store, and that is a materials fault
• The room is leaking light, since the working packet has been out in it
• Nothing, because two sheets cannot separate three causes

Show the answer and why

Answer: The developer is excluded, because it treated both sheets identically — the box you have been printing from has been fogged in store, and that is a materials fault

The pair is a controlled comparison in which exactly one thing differs: which packet the sheet came from. Both sheets met the same developer for the same time at the same temperature in the same session, so any fault in the bath would have marked both. It marked one, so the difference belongs to the material. That is the whole reason the fresh, unopened packet is worth the price of a sheet — without it, storage fog and developer fog are indistinguishable on a print, and the printer who lacks the control usually blames the chemistry, mixes fresh, and gets the same grey again.

Question 5. Your prints look dull dry after looking right wet, and the difference is about the size of the dry-down you measured in this part. What follows?

• The developer is weak and should be replaced
• This is not a chemistry fault: it is a viewing problem, settled by judging dry prints under the light they will be seen in and applying your measured correction at the timer
• The paper is fogged and a fresh box is needed
• The fixer has reduced the silver image

Show the answer and why

Answer: This is not a chemistry fault: it is a viewing problem, settled by judging dry prints under the light they will be seen in and applying your measured correction at the timer

The value of measuring dry-down is that it converts an argument into a comparison. If the shortfall matches your own measured figure for this paper, this developer and this drying method, the print behaved exactly as the material does and nothing is broken; the mistake was judging a wet print under an inspection lamp against a dry print’s standard. If the shortfall is several times the measured figure, dry-down cannot account for it and the differential on this page applies. Without the measurement, a printer has only a feeling on each side of the question, which is how one habit gets blamed for another habit’s fault for years.

Question 6. On which evidence would you hand the case back to Part XVI rather than continuing here?

• The blacks are dull and the developer was mixed four days ago
• An even grey veil that includes the white border the easel blades masked, with both unexposed control sheets clean
• A yellow stain at the borders that appeared as the prints dried
• The image takes longer than usual to appear

Show the answer and why

Answer: An even grey veil that includes the white border the easel blades masked, with both unexposed control sheets clean

A border under an easel blade was masked from everything that came through the lens, so a veil that covers it did not arrive from the enlarger — but a veil that covers it on a sheet whose developer left a fresh sheet clean did not arrive from the chemistry either. What is left is light reaching the paper by another route, or the room, which is precisely the differential Part XVI runs with its five fog sources and its eight sources of unevenness. The other three options are all chemistry signatures this page owns, and the boundary sentence covers both directions: whites are that page, blacks with clean whites are this one.

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