Break/Fix: The Printed-Out Image That Faded

The situation

Six prints, six different failures, and one thing in common: the print itself will not tell you what happened. Two of these faults look almost identical and have opposite causes; one of them is not a processing fault at all but the mount; and one of them will not appear for a month, by which time you will have made forty more prints the same way.

So this page works from the record rather than from the picture. That is the discipline it teaches, and it is why the two labs before it ask you to write down so much.

The failures here belong to printed-out silver, not to salted paper alone. Every one of them recurs in Part XXIII’s albumen prints and in Part XXIV’s Van Dyke and kallitype prints, because all three make a finely divided silver image in or on plain paper, fix it in thiosulfate and wash it. The section on what carries across says which of the six travel unchanged, which change their emphasis and which belong to salted paper alone.

Before you start

This page is Level B and it is diagnostic, which means remaking prints. Every control from the two labs applies again in full: chemical splash goggles for the silver nitrate, nitrile gloves, everything silver-bearing collected, and — if a thiocyanate toner is anywhere in the room — no acid, because the International Chemical Safety Card for sodium thiocyanate records a violent reaction with acids and the old EC classification quoted on it carries R32, contact with acids liberates very toxic gas.

Two of the tests on this page bring their own reagents, and both need handling that the printing sessions did not.

⚠The two test reagents, and the sequencing that keeps them apart

The residual silver test uses a sulfide reagent. Keep it away from every acid on the bench and use it with ventilation, per the test SOP. And keep it off the picture: a sulfide reagent on nanoparticle silver is the sulfiding reaction this page is diagnosing, and Ware’s extinction coefficients say what complete sulfiding costs — a drop in maximum optical density by a factor of about thirty. A drop on a test strip, never a test in the image area.

The residual thiosulfate test reagent contains acetic acid — HT-2 is silver nitrate in dilute acetic acid. Do it last, with the toner bottled and the bench cleared, for the reason above. This is a sequencing control rather than a housekeeping preference, and it is written into the order below. Its other ingredient is a second reason to keep it on a strip: you are putting fresh silver nitrate onto a sheet, and Kodak’s own storage note warns that it stains negatives, prints and hands black.

And the sulfide test is genuinely useful evidence rather than a formality, because its chemistry is known to work on these papers. John Spiller detected residual silver in the whites of albumen prints in 1868 by exactly this route: he moistened a white area with ammonium sulfide and watched a brown stain appear. What has not been established, for any of these papers, is the quantitative comparison against a printed patch — see the caveat in the printing lab.

Work on strips, not on prints you care about. A sensitised, unexposed, identically processed strip from the same session answers most of the questions here and costs a fraction of a sheet.

Alternative route

This page declares requiresUV because diagnosis means printing again, and printing means ultraviolet. The sun is the alternative and it is the historical one, with the three cautions the printing lab sets out: a dull sky is not a slow sun, sensitivity falls off below about 5 °C, and the frame is never opened in the light you are printing by.

But most of this page needs no printing at all, and that is worth saying plainly. Four of the six cases are diagnosed from the record and a test strip, not from a new print:

• Case one is settled by the processing record and a strip from the same session.
• Case two is settled by two chemical tests on strips.
• Case three is settled by looking at where the damage is, and at the mount.
• Case six is settled by looking, and by the storage history.

Only cases four and five need a fresh print to confirm a hypothesis, and even those can be worked one variable at a time on small strips rather than on full sheets. A reader with no ultraviolet source at all can still do the whole of the evidence-gathering and most of the diagnosis; what they cannot do is the confirmation. Say so in the notebook when that is the position, rather than recording a diagnosis as though it had been tested.

And one thing has no alternative: the tests need running water and reagents. Where those are not available, the honest route is the troubleshooting atlas, which carries every one of these faults as an entry that can be read against somebody else’s evidence.

The symptoms

Lay the failed prints out and sort them by where and when, because those two questions do more diagnostic work than any description of colour.

#	What you see	Where	When
1	The image almost disappears, in the tray	Overall	In the fixer, in minutes
2	Yellow-brown stain in the whites and highlights	Non-image areas first	Over weeks to months
3	Fading that begins at the edges and works inwards	Edges, or a band at one edge	Over months to years
4	A weak print that never looked strong, with no real black	Overall, from the start	Immediately, and it never improves
5	The print comes out of the toner the colour it went in	Overall	In the toner, over 15 minutes of nothing
6	A metallic bluish sheen by reflected light; or a general loss and a shift to flat yellow-brown	Sheen at the edges; loss overall	After long storage

Two of these look like each other and are not. Case 2 and case 6 both end in a yellow-brown print, and Reilly’s account of the human visual system explains why they are so easy to miss for so long: the eye pegs the lightest area in a print as a reference white, so a print whose highlights have stained looks acceptable until it is laid beside a true white. He is candid that it is fortunate we compensate like this, since otherwise a majority of albumen photographs would look excessively flat and lifeless — and equally candid that it is why the problem has received less attention than it deserves. Get a sheet of the unexposed, unprocessed paper out and put it next to the print.

Evidence to collect

Before any test, and before any hypothesis.

The processing record, which is the whole reason for the tables in the two labs. For the print in question: paper and salting batch, silver bath strength and batch, hours between sensitising and printing, exposure conditions and end point, first wash duration and how many changes, toner and its age and how many prints it had already taken, fixer strength and route and how many prints had gone through it, every wash time, and the dry-down measurement.

The unprocessed paper, as the reference white.

A strip from the same session, sensitised and processed identically but never exposed. This is the single most useful object in the diagnosis and it costs almost nothing to make; it carries the same residues as the print with none of the image.

The negative, and its measured density range if you have one.

The mount and the enclosure, if the print has been in either, and what they are made of.

The water, measured with narrow-range pH paper.

And the print itself, read in three ways. Reflected light at a low angle, for surface and sheen. Transmitted light on a light table, for what has actually gone. And magnification, for where the damage sits relative to the fibres.

📓What a printed-out print carries about its own processing, and what it does not

A salt print is unusually informative about its own history, because so much of the process leaves a visible trace. Six things you can read off it.

Whether it was toned, from the colour: untoned prints run light brown to reddish brown, in the Getty Atlas’s description, and toning moves that towards purple and cooler.

Whether it was over-exposed or under-exposed relative to its fixer, from the relationship between the picture and the margin outside the negative. The margin got the full exposure with nothing in the way, so it records the maximum density the sheet and the processing could reach.

Whether the first wash was done, from the highlights. Free silver nitrate left in the sheet is what makes black stains in the fixer and yellow-brown stains later.

Whether the coating was even, from the pattern of the fault: round hard-edged white spots are bubbles at sensitising, round spots with a brown stain are bubbles at salting, broad blotches are silver on the back, and light patches only in the densest areas are Reilly’s “measles” — insufficient sensitisation.

Whether it dried against something, from marks that follow a shape rather than the picture.

And whether the damage came from outside, from where it is: edges and one side point at the atmosphere, the frame or the mount; uniform loss points at what is inside the paper.

What it does not carry. It will not tell you the fixer’s strength, the number of prints that went through that bath, the wash time, or how long it had been sensitised. Those are the four things that matter most, and none of them is visible. Which is the argument of this page in one sentence.

Hints, in increasing order of disruption

Work down this list and stop as soon as one of them settles the question. Each costs more than the one above it.

1. Put the print beside the unexposed paper. Free, instant, and it settles whether the highlights have stained at all.

2. Read the processing record for the two numbers that are invisible in the print: how many prints that fixer had already taken, and how long the final wash was.

3. Look at the margin. If the margin outside the negative is also weak, the fault is in the sheet or the exposure, not in the negative.

4. Look at where the damage is, at a low angle and then on a light table. Edges and one side is an external cause; uniform is internal.

5. Run the residual silver test on a strip from the same session. Cheap, quick, and it separates the commonest pair of confusable causes.

6. Run the residual thiosulfate test on a strip. Last, with no acid near the toner.

7. Reprint one variable. Only now, and only one.

The diagnosis

Case one: the print that vanished in the fixer

Three causes, and the print cannot distinguish them. The record can.

Over-strong or over-long fixing. Reilly’s account of what a fixer does to a printed-out image is in the chemistry lesson: the dramatic colour and density change is mostly physical — the silver chloride leaves, the refractive index falls, the particles pack — but a bath that is too strong, too long or acid takes real silver as well. Bostick & Sullivan state the failure in one line: over-fixing can lead to bleaching of the image.

An acid fixer, which is the same fault with an extra mechanism. Reilly gives both reasons an alkaline bath is specified: an acid bath decomposes the thiosulfate and liberates sulfur, and it attacks the finely divided image silver directly, causing excessive bleaching of the highlights and middletones. Ware records the historical demonstration — Malone’s addition of nitric acid at the Reading establishment gave a “rich mulberry tint” and was probably one of the causes of the fading those prints became notorious for.

No first wash. Free silver nitrate carried into the fixer is complexed at the bath’s expense, and Reilly says what happens next: black stains.

Or the print was simply never exposed deep enough. Every source says the print must be over-printed and gives a figure: Reilly about two stops, Bostick & Sullivan one half to two thirds of the final darkness, Photographers’ Formulary the marked step plus about four more.

=Telling the four apart from the record, not from the print

Read this in the record	If it says	The cause is
Fixer strength and time	10 or 15 per cent, or longer than the published time	Over-fixing
Fixer identity	anything with “rapid”, “hardening” or an acid pH	Acid attack, and see the safety rule at the top of this page
First wash	fewer changes than it took for a trayful to stay clear	Free silver carried into the fixer — and look for black stains, which are diagnostic of this one alone
Exposure end point	“looked right”, or fewer than two stops of overprint	Under-exposure
Fixer history	more than 10 to 15 prints of this size per litre	Exhaustion, which is case two’s mechanism arriving early

The one visible discriminator is the black stain. Reilly names it specifically as the consequence of unremoved silver nitrate meeting the fixer, and none of the other three causes produces it. If there are black stains, you have your answer without reading anything.

And the margin is the second discriminator. If the margin — which received full exposure through nothing — is also weak, the sheet or the fixer is at fault. If the margin is strong and the picture is weak, the exposure or the negative is.

The atlas entry is the printed-out image bleached in the fixer.

Case two: yellow-brown highlight stain appearing over weeks

Three causes, and here a test does separate them.

Residual silver compounds. Silver that the fixer did not remove, converting slowly to silver sulfide. The evidence that this happens at all is the nineteenth-century chain in the chemistry lesson: Davanne and Girard in 1859 found that 2 per cent potassium cyanide removed all the silver from an albumen print where strong hypo did not; Spiller in 1868 detected it with ammonium sulfide; Haddon and Grundy measured it at nearly 5 per cent of the applied silver in a thoroughly fixed and washed but never exposed albumen print. That figure is for albumen and does not transfer to a plain salted paper, whose retention mechanism is different — but the principle does.

Insufficient washing. Residual thiosulfate, decomposing and supplying sulfur from inside. Reilly’s statement of why this is worse here than on a modern paper is the structural one: there is no baryta and gelatin substratum between the image and the base, so the base paper becomes a reservoir of image-threatening substances.

An exhausted fixer, which is a cause of the first two rather than a third mechanism. Reilly’s account of why is chemical: as a bath approaches exhaustion it loses the ability to form soluble silver-thiosulfate complexes, and one of the complexes that does form is soluble only in fresh thiosulfate. A print fixed in an exhausted bath is not under-fixed in any way you can see; it is carrying a complex that will not wash out.

⚗The test that separates them, and what each result means

Two tests, on strips from the same session, run in this order.

ST-1, residual silver, first, because it needs no acid. A brown stain where the reagent touched an unexposed, fully processed strip means silver that the fixer left behind.

HT-2, residual thiosulfate, last, after the toner is bottled, because the reagent is acidic.

ST-1	HT-2	The diagnosis
Positive	Negative	Residual silver. The fixer did not remove it: check strength, time and, above all, how many prints that bath had taken
Negative	Positive	Insufficient washing. Extend the wash, and check the sulfite bath was used and was fresh
Positive	Positive	An exhausted fixer, which produces both at once — the classic signature
Negative	Negative	Look outside the print: the mount, the enclosure, the atmosphere. That is case three or case six

And read the caveat with the result. Both tests were devised for gelatin-coated papers and neither is calibrated on an uncoated sheet, so a comparative result between two of your own strips is meaningful and an absolute reading against a printed patch is not. The residual silver test is on firmer ground because Spiller’s 1868 experiment is exactly this chemistry on exactly this kind of paper.

A non-destructive professional route exists and is worth knowing about: the AIC note that XRF identifies the silver image and can also detect sulfur where the image was fixed in sodium thiosulfate.

The atlas entries are yellow-brown highlight stain from residual silver and residual thiosulfate.

Case three: the print that faded at the edges first

Where the damage is tells you which of three it is, and this is the case that is not a processing fault at all.

Incomplete coating. If the fade is at an edge that was never properly coated, it was thin from the start rather than faded. Look for it on the unmounted margin, and compare against the record’s coating method: a floated sheet is thin where it lifted, a brushed or rodded one where the stroke ran out.

Uneven washing. A print washed flat in a tray, or one that stuck to another print or to the tray bottom, washes unevenly, and the part that washed least keeps the most thiosulfate. The pattern follows the tray, not the picture.

Or the mount and its adhesive, attacking from behind. Reilly’s account is the fullest and it is a documented cause rather than an inference. A typical nineteenth-century mount was thin, good-quality paper over a core loaded with lignin; the decomposition products migrate through the top layer and attack the photograph, causing staining and brittleness and accelerating fading and yellowing of the silver image. Putrefied starch or gelatin adhesives do the same. Reilly adds that the danger is especially acute where the print is on thin stock, because very little barrier exists between the silver image and the mount — and that about 95 per cent of albumen prints were mounted at the time of production. IPI’s reactant-damage table names lignin and acids as attackers with their own damage modes, and their framing guide makes the general point that the frame is part of the chemistry.

How to tell them apart. Coating faults are present from the start and visible on a print made the same day; washing faults follow the geometry of the tray; mount faults follow the geometry of the mount and are worst where the print is in closest contact with it, and often show brittleness or foxing on the board as well.

Which is also the one case with a proven treatment. Reilly: removal of prints from obviously defective mounts and careful remounting onto appropriate material with safe adhesives is the only technique for the preservation of albumen prints that has proven itself in practice — with the honest qualification that remounting does nothing to reverse damage already done.

The atlas entry is edge fading from mount and adhesive.

Case four: weak maximum density, and an image that never looked strong

Four causes, and they divide cleanly by where the weakness is.

Too little silver. An exhausted or over-diluted bath, or too short a float, or a brush coating that put down less than it should. Reilly’s name for the visible result is the “measles” — blotches or light spots specifically in what should be the densest areas of the print — and his causes are a too-weak silver solution or insufficient residual sensitiser in the paper. His remedy is useful and limited: nothing can be done for prints already exposed, but unexposed sheets suspected of the same problem may be re-floated or re-brushed with a stronger solution.

Too little chloride. Reilly: lowering the chloride content tends to produce prints that lack brilliance and density. His working range is 2 to 2.5 per cent chloride with the silver bath at 10 to 12 per cent, and the historical drift to lower chloride in albumen paper — down to 1 to 1.5 per cent in the 1880s and 1890s — was an accommodation to thinner negatives that cost image silver.

Too weak a negative. This is the commonest cause and the easiest to miss, because the print looks like a processing failure. Reilly is categorical that even the densest and most contrasty negatives that print satisfactorily on develop-out papers do not have enough density range for these papers, and that a compromise negative prints well on neither kind.

Or a paper that swallowed the sensitiser. Reilly’s diagnostic here is elegant and needs no equipment: if a print looks better by transmitted light than by reflected light, the solutions sank too deeply into the paper fibres, and either a pre-sizing step or a more viscous coating is needed. He also names the underlying variable: with plain salted papers the porosity of the rawstock remains the largest single factor in the result, and a porous stock such as watercolour paper will yield very flat prints indeed.

=Separating the four in one sheet

Look at the margin first. It received full exposure through nothing at all, so it shows the maximum density this sheet and this processing could reach.

• Margin weak, picture weak → the sheet or the processing. Go to the sensitiser or the salting.
• Margin strong and bronzed, picture weak → the negative or the exposure, not the sheet.

Then hold the print up to the light. Better by transmission than by reflection → the coating sank in, and the fault is the paper or the binder.

Then look at where the weakness is. Only in the darkest areas, blotchy → the measles, so insufficient sensitisation. Uniformly flat with no black anywhere → chloride, or the negative.

And then read the negative’s density range if you have a densitometer. This is the measurement that ends the argument, and the negatives lesson owns it.

Case five: the toner that did nothing

Reilly lists eleven factors that influence the outcome of toning, which is a warning in itself: the pH of the binder, the pH of the silver solution, the amount of image silver, the thoroughness of the initial wash, the pH of the toning solution, other substances in it, the strength of the gold, its temperature, its age, and the time of immersion. Four of them account for nearly every case of a bath that does nothing.

Free silver carried in from an omitted or short first wash. Reilly’s Step 1 is unambiguous: if the excess silver nitrate is not removed at this stage it will retard or completely prevent any toning from taking place. Bostick & Sullivan’s rinse before toning is described as removing the excess silver and prepping the surface to absorb the toner evenly. This is the first thing to check, because it is common, cheap to fix and wastes the most expensive consumable on the bench.

A bath at the wrong pH. For an alkaline bath this cuts two ways. Not alkaline enough, or not ripened: the gold is still gold(III), still acidic, still relatively inactive — and Reilly’s visible test is that the stock keeps its yellow in that state and goes colourless when it has passed into the active one. Too alkaline: it tones quickly and loses activity much more rapidly, and Reilly warns that making the toner too alkaline results in baths that still contain a great deal of gold and no longer tone prints.

Or the bath is simply spent. Most alkaline baths are intended for one-use toning and become inactive spontaneously after a few hours, and Reilly says plainly that there is no clue other than the cessation of toning action to indicate the point. Bostick & Sullivan’s thiocyanate bath is replenishable and they publish the rule: about 5 mL of gold stock per print, or 25 mL when the toning slows to an impractical speed.

Or a trace of fixer got in. Reilly: the toner solution is ruined by even a trace of fixer, so cleanliness and care are required. A tray, a pair of tongs or a glove that went from the fixer to the toner does it.

✕The one that looks like a dead toner and is not

A print that comes out of a thiocyanate bath paler than it went in has not failed; it has bleached and not yet intensified. Reilly explains the sequence: thiocyanates are solvents of silver chloride, so the image at first bleaches and then intensifies as the gold is deposited. Pull it at the bleach and you have made the print worse for nothing.

And the opposite failure has a distinctive look. An acidic gold(III) bath — an un-neutralised gold chloride solution — deposits one gold atom for every three silver atoms it dissolves, so the toning lags far behind the bleaching and the result, in Reilly’s own words, is a flat, lifeless image with a reddish colour. A print that came out of a gold bath paler, flatter and redder was toned in the wrong oxidation state.

The atlas entry is the gold toner that did nothing.

Case six: silver mirroring and sulfide staining after long storage

Two faults, told apart by how you hold the print, and they travel together because the conditions that cause one favour the other.

Mirroring is a metallic, often bluish sheen seen by reflected light and not by transmission, typically starting at the edges. IPI’s own glossary defines it as an oxidation of black-and-white images in which the image silver migrates to the surface, creating a mirror-like appearance, and their framing guide gives the sequence: reactions from poor framing materials, like those from air pollution, are often oxidations that fade the image, and the faded silver can migrate to the surface and be converted back into metallic silver by other pollutants. So the sheen is the same silver that left the image.

Ag → Ag⁺ + e⁻

Oxidative attack: image silver gives up an electron to an oxidant and becomes mobile

Ag⁺ + e⁻ → Ag

And is reduced back to the metal at the surface, where it makes the sheen

Sulfiding is a general loss and shift seen by ordinary viewing: density gone, colour moved towards a flat yellow-brown, highlight detail lost.

2 Ag + S → Ag₂S

Sulfiding, as the conservation literature states it in words

Why an untoned printed-out print is especially vulnerable, in three numbers already established. There is about 3 mg of silver in a whole-plate salt print, roughly a tenth of a modern print; the particles are perhaps a hundredth the size, so the surface area is about a hundred times larger; and complete conversion to silver sulfide drops the maximum optical density by a factor of about thirty. Ware’s summary is that it takes very little hostile impurity to react with this tiny amount of silver and cause the print to fade — and he adds the specific case for a plain sheet: like any colloidal silver image, especially one on plain paper unprotected by a colloid binder layer, it is inevitably rather susceptible to attack by oxidising acids and sulfur-containing substances.

Why it goes yellow rather than black, which surprises people who know that bulk silver sulfide is black. Ware’s answer has two parts: at nanoparticle thickness you see only the attenuated absorption of silver sulfide, whose band is centred in the ultraviolet and tails into the blue; and the extinction coefficients differ by a factor of nearly thirty. And the same paragraph explains why a little sulfiding enriches a print: Henglein found that dilute sulfide shifts a silver sol’s absorption towards the green, turning it yellow to brown, before air replaces the band altogether with the feeble spectrum of colloidal silver sulfide.

!What an enclosure can and cannot prevent

It can address the outside half. Reilly divides the causes of generalised image fading into internal — residual thiosulfate and silver-thiosulfate complexes — and external, being atmospheric sulfur compounds such as sulfur dioxide and oxidising gases such as ozone and organic solvents. An enclosure works on the second list only. IPI’s reactant-damage table is the shopping guide: it pairs each layer of a photograph with the reactants that attack it — unstable colorants, oxidising agents, reducing agents, chromophores, high alkali, acids, lignin — and the damage each produces, including image fade and silver mirroring. The Photographic Activity Test, which is an International Standard in its own right (ISO 18916), is what to look for on a product.

It cannot address the inside half at all. Residual thiosulfate in the fibres is inside the enclosure with the print, and Reilly’s structural point is that on a paper with no baryta layer it is already in contact with the image.

And storage is a slope rather than a threshold. The AIC give 18 to 30 °C, stable, to avoid embrittlement, at 30 to 50 per cent relative humidity; Reilly gives the tighter 18 to 20 °C at 35 to 45 per cent, on the reasoning that temperature and humidity govern the rate of every destructive reaction. IPI’s preservation metrics explain why both are defensible: the effects of the environment follow a continuum, there is no clean line of temperature or humidity dividing storage into good and bad, and their Preservation Index expresses the difference in years rather than as a pass or a fail.

There is no treatment in this course. Reilly’s finding for the nearest studied case is discouraging: albumen prints do not respond to the bleach-and-redevelop methods that have restored sulfided gelatin materials, because the residual silver in the highlights redevelops along with the image, the redevelopment does not give sufficient density, and the restored colour is out of character with the original.

The atlas entries are silver mirroring and sulfiding on printed-out prints and silver mirroring.

The fix

For each case, in the order you should attempt it.

Case one — vanished in the fixer. Confirm from the record. If the fixer was wrong, remake it: the plain 5 per cent bath or Reilly’s alkaline 15 per cent two-bath, fresh, at the published time and no longer. If the first wash was short, wash until a trayful stays clear. If the exposure was shallow, add the two to three stops your own dry-down measurement calls for. Never fix an already-bleached print again; there is nothing to recover.

Case two — highlight stain. If ST-1 is positive, the problem is the fixer, and the answer is fresh fixer at Reilly’s conservative capacity of no more than 10 to 15 prints of this size per litre — against the literature’s 150, which he explicitly rejects for permanence work. If HT-2 is positive, rewash: a print can be rewashed at any time, and the sulfite bath followed by a long wash is worth doing on a print you value even if it has been dry for months. If both are positive, do both.

Case three — edge fading. If it is the mount, remount, which Reilly calls the only proven preservation treatment for these prints. If it is coating or washing, it is a technique fix on the next print and there is nothing to do for this one.

Case four — weak density. One variable at a time, and start with the one the margin points at. Stronger or fresher silver bath; more chloride; a longer-scale negative; or a less porous paper or a pre-sizing step. Reprint two strips, changing one thing, and keep the old strip beside the new.

Case five — dead toner. Wash the next print properly first; that is free. Then check the bath’s colour against Reilly’s yellow-to-colourless test. Then mix a fresh bath, and if it is a thiocyanate one replenish it on the supplier’s published rule instead of remaking it each time. Discard any bath suspected of fixer contamination; it cannot be rescued.

Case six — mirroring and sulfiding. Get the print away from what is attacking it: out of the frame, off the mount, into a tested enclosure. Tone the reprint. On an unprotected silver image, toning is a permanence operation before it is an aesthetic one, and Ware notes the image is receptive to the usual toning treatments where improved permanence is wanted.

⚗Prevention, in four steps that account for most of these failures

Every one of the six cases traces back to one of four operations, and the two labs put all four under your control.

1. Exposure depth. Two to three stops past what looks right, measured as your own fix-down rather than taken from a book. Under-exposure is a cause of case one and case four, and it cannot be fixed afterwards.

2. The first wash, to completion. Not a time — a trayful of water that stays clear. It is the whole of the prevention for case five, half of case one, and part of case two.

3. Fixer strength, freshness and time. Fresh every session; the published strength; the published time and no longer; and 10 to 15 prints per litre, not 150. This is the prevention for cases one, two and six.

4. The final wash, tested. The sulfite bath and thirty minutes or more, and then ST-1 and HT-2 on a strip. Reilly’s admission that experimental evidence on the washing of these papers is almost nonexistent is precisely why the test replaces the trust.

And there is a fifth that is not a processing step: tone. It is the only intervention that acts on the image silver itself, and the 1855 committee’s two recommendations were the same two this list ends on — thorough washing, and gold.

Which of these belong to Parts XXIII and XXIV as well

This page serves three parts, and it is worth being exact about which faults travel and which do not.

What carries across the printed-out silver cluster

1. 1Cases one, two and six travel unchangedBleaching in the fixer, highlight stain from residual silver or thiosulfate, and mirroring and sulfiding in storage are properties of a finely divided silver image fixed in thiosulfate. Albumen, arrowroot, Van Dyke and kallitype prints all have one
2. 2Case three travels, and gets worse in Part XXIIIReilly says about 95 per cent of albumen prints were mounted, on thin stock, so the mount is a larger threat there than here — where most salted papers can simply be matted
3. 3Case five travels to every process that is gold tonedWhich is all of them: the same bath, the same eleven factors, and the same fatal trace of fixer. Bostick & Sullivan sell one kit for POP, Van Dyke, kallitype, albumen and salt prints
4. 4Case four travels in form and changes in causeA weak maximum density is a weak maximum density everywhere, but Part XXIV's iron-silver processes reach it by a different route — the iron chemistry — and their own break/fix entry is separate
5. 5And two things here are salted paper's aloneThe "measles" of insufficient sensitisation, which needs a two-step salted paper to happen at all; and the highlight yellowing peculiar to albumen, which is Part XXIII's and comes from sulfur-containing side groups on the egg protein that a cellulose sheet does not have

One caution about transferring numbers rather than mechanisms. Haddon and Grundy’s 5 per cent of residual silver is an albumen figure and depends on albumen’s protein chemistry. Reilly’s 10 to 15 prints per litre of fixer is for these papers as a class. Ware’s 3.3 mg of image silver is for a salt print. Take the mechanism across and leave the number where you found it.

The related atlas entries are the iron-silver print that faded and cross-contamination between alternative processes, which becomes the commonest fault in any darkroom running two of these at once.

What to record

For each failed print, before anything is thrown away:

Record	Why
The complete processing record, from both labs’ tables	Four of the six causes are invisible in the print and visible only here
The reference comparison	Which unexposed sheet you laid it beside, and what the difference was
Where the damage is	Edges, one side, uniform, or following the tray or the mount
Reflected against transmitted appearance	Mirroring shows in one and not the other; a sunken-in coating shows the opposite way round
The margin’s density against the picture’s	The single most useful observation on the page
ST-1 and HT-2 results	With the strip they were run on and its wash regime, and marked as comparative rather than absolute
Water pH	Narrow-range paper is enough
The mount and the enclosure	What they are, and how long the print was in them
Your hypothesis, before the test	And whether it survived

And the discipline that makes the rest of it worth anything: write the hypothesis down first. A test run after you have decided the answer tends to confirm it.

Keep the failed prints. Reilly’s own advice for learning identification applies here too — the fault atlas you build from your own failures is the one you will actually recognise later, and a print that vanished in the fixer is the clearest teaching object for that fault that will ever be on your bench.

Questions

1. A print bleached almost to nothing in the fixer. Name the four possible causes and say which single visible feature settles one of them without reading the record.
2. Your ST-1 comes up positive and your HT-2 negative. What has gone wrong, and what do you change?
3. Why does a print with stained highlights look acceptable for years? Name the mechanism, and the one object that defeats it.
4. A print is weak, with no real black. What do you look at first, and why does the margin answer a different question from the picture?
5. Your gold toner produced no change in fifteen minutes. List four causes in the order you would check them, cheapest first.
6. Why does silver sulfide make a salt print go yellow rather than black? Two reasons.
7. An enclosure that has passed the Photographic Activity Test protects a print from some things and not others. Which, and why?
8. Which of the six faults on this page would you expect to see on an albumen print, and which would you not?

Recap

The print will not tell you what happened; the record will. Four of the six causes — fixer strength, fixer history, wash time and how long the sheet had been sensitised — leave no visible trace at all.

The margin is the most useful thing on the sheet. It received full exposure through nothing, so it separates a sheet-or-processing fault from an exposure-or-negative fault in one glance.

Two tests separate the commonest confusable pair, residual silver from residual thiosulfate, and both are positive when a fixer is exhausted. Both are comparative on this material rather than absolute, and the residual silver test’s chemistry is the one Spiller used on these papers in 1868.

Where the damage is tells you where it came from. Edges and one side means the atmosphere, the frame or the mount; uniform means what is inside the paper.

A dead toner is usually a short first wash, and that is free to fix.

Untoned printed-out silver is the most vulnerable image in the course — a tenth the silver, a hundred times the surface area, and a thirtyfold density loss on complete sulfiding — and the only intervention that acts on the image itself is toning.

Four steps prevent most of it: exposure depth, a first wash carried to completion, a fresh fixer at the published strength and time, and a final wash you test rather than trust.

Check your understanding

Question 1. Three prints bleached badly in the fixer. Their records differ in one respect each: one was fixed for twenty minutes, one used a rapid fixer from the shelf, one had a two-minute first wash. Which of these can also be diagnosed from the print itself?

• The over-fixed one, by its colour
• The one with the short first wash, because free silver nitrate carried into the fixer produces black stains, and neither of the other two causes does
• The rapid-fixer one, because the bleaching is more uniform
• None of them; all three look identical

Show the answer and why

Answer: The one with the short first wash, because free silver nitrate carried into the fixer produces black stains, and neither of the other two causes does

Reilly names the black stain specifically as the consequence of silver nitrate that was not removed by the initial wash being present when the print is fixed, and no other cause on the list produces it. The other two are told apart only by the record - twenty minutes against the published four to five, and an acid rapid fixer against a plain or alkaline one. That asymmetry is the argument of the whole page: the print carries some evidence about its own processing and not the parts that matter most.

Question 2. A residual silver test on a processed strip is positive and a residual thiosulfate test on the same strip is negative. What is the diagnosis?

• Insufficient washing; extend the final wash
• Silver the fixer failed to remove; check the fixer's strength, its time and above all how many prints that bath had already taken
• The print was under-exposed
• The mount is attacking the print from behind

Show the answer and why

Answer: Silver the fixer failed to remove; check the fixer's strength, its time and above all how many prints that bath had already taken

The two tests separate the two internal causes, and the combination is the diagnosis. Silver present with thiosulfate absent means the wash worked and the fixer did not. Reilly's conservative capacity for maximum permanence is no more than 10 to 15 prints of about 8 by 10 inches per litre, against the literature's estimate of up to 150 in a 15 per cent bath, and his reason is the high silver content of printing-out papers relative to develop-out materials. Both tests positive together is the classic signature of an exhausted bath, which produces residual silver and unwashable complexes at once.

Question 3. Why does a print with yellowed highlights look acceptable for years?

• Because the yellowing is genuinely slight until a threshold is crossed
• Because the human visual system automatically pegs the lightest area in a print as a reference white, so a side-by-side comparison with a true white is needed to see it
• Because yellow is close to the paper colour and the eye is insensitive there
• Because the stain forms under the image layer and only migrates upward slowly

Show the answer and why

Answer: Because the human visual system automatically pegs the lightest area in a print as a reference white, so a side-by-side comparison with a true white is needed to see it

Reilly is explicit that this adaptive mechanism is why the problem has received less attention than it deserves, and equally candid that it is fortunate we have it - otherwise a majority of albumen photographs would appear excessively flat and lifeless. The practical consequence is the cheapest diagnostic on the page: get a sheet of the unexposed, unprocessed paper out and lay it against the print. It costs nothing and it settles whether the highlights have stained at all.

Question 4. A gold toner produced no visible change in fifteen minutes. In what order would you check the possible causes?

• Buy fresh gold first, then check everything else
• The first wash, then the bath's colour and pH, then whether the bath is spent, then whether fixer contaminated it - cheapest and commonest first
• Check for fixer contamination first, since it is fatal
• Increase the toning time to thirty minutes and see

Show the answer and why

Answer: The first wash, then the bath's colour and pH, then whether the bath is spent, then whether fixer contaminated it - cheapest and commonest first

Reilly lists eleven factors that influence toning, and the four that account for most dead baths have very different costs to investigate. Free silver from an omitted or short first wash will retard or completely prevent toning and is free to fix on the next print. The bath's state can be read from its colour: an acidic, relatively inactive alkaline bath keeps its yellow and a working one is colourless. An alkaline bath is usually one-use and goes inactive spontaneously after a few hours with no clue but the cessation of toning. And a trace of fixer ruins the bath outright, which is fatal but also the least likely if the trays are labelled.

Question 5. Which two processing steps, done properly, would prevent four of the six faults on this page?

• Exposure depth and toning
• The first wash carried to completion, and a fresh fixer at the published strength and time
• The final wash and the sulfite bath
• Coating evenly and drying in the dark

Show the answer and why

Answer: The first wash carried to completion, and a fresh fixer at the published strength and time

The first wash prevents case five outright - free silver retards or completely prevents toning - and is part of the prevention for case one, where free silver carried into the fixer produces black stains, and for case two, where it contributes to the residual silver. A fresh fixer at the published strength and time prevents the bleaching of case one, the residual silver and unwashable complexes of case two, and much of the vulnerability behind case six. Exposure depth and the final wash are the other two of the four steps in the prevention list, and toning is the fifth intervention, which acts on the image silver rather than on the residues.

Question 6. Why does complete sulfiding turn a salt print yellow rather than black, when bulk silver sulfide is black?

• At nanoparticle thickness you see only the attenuated absorption of silver sulfide, whose band is centred in the ultraviolet and only tails into the blue
• The extinction coefficient of nanoparticle silver sulfide is about 560 against about 16,000 for nanoparticle silver, so the density drops by a factor of nearly thirty
• The silver sulfide is dissolved by the residual thiosulfate and only a trace remains
• The paper fibres scatter the shorter wavelengths preferentially

Show the answer and why

Answer: At nanoparticle thickness you see only the attenuated absorption of silver sulfide, whose band is centred in the ultraviolet and only tails into the blue, The extinction coefficient of nanoparticle silver sulfide is about 560 against about 16,000 for nanoparticle silver, so the density drops by a factor of nearly thirty

Ware gives both parts of the answer. A salt print has very little silver to begin with - about 3.3 mg in a whole plate on his figures, roughly a tenth of a modern print - so there is no density to spare when the covering power falls by a factor of thirty. And the same paragraph explains the paradox of the old hypo colouring bath: Henglein found that dilute sulfide first shifts a silver sol from yellow towards brown by surface adsorption, which enriches an image, before further exposure replaces the absorption band with the feeble spectrum of colloidal silver sulfide, which destroys it.

Question 7. A print has faded worst along one edge and shows brittleness and brown flecks on the board it is mounted to. What is the most likely cause and what is the treatment?

• Uneven washing; rewash the print
• A lignin-loaded mount board whose decomposition products are attacking the print, with foxing on the board as a corroborating sign; the treatment is removal from the defective mount and careful remounting, which Reilly calls the only preservation technique for these prints that has proven itself in practice
• Incomplete coating; there is no treatment
• Atmospheric ozone; the treatment is a better frame

Show the answer and why

Answer: A lignin-loaded mount board whose decomposition products are attacking the print, with foxing on the board as a corroborating sign; the treatment is removal from the defective mount and careful remounting, which Reilly calls the only preservation technique for these prints that has proven itself in practice

The geometry is the discriminator: a coating fault follows the coating stroke, a washing fault follows the tray, and a mount fault follows the mount and usually shows on the board as well. Reilly describes the typical nineteenth-century mount as thin good-quality paper over a lignin-loaded pulp core whose decomposition products migrate through the top layer and attack the photograph, causing staining and brittleness and accelerating fading and yellowing, with foxing from mould, fungus or metallic salts in the board. His qualification belongs with the treatment: remounting does nothing to reverse the deterioration that has already occurred.

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