Lab: Washing, Drying, Flattening and Mounting the Print

The print you took out of the fixer is not finished. It is wet, full of thiosulfate, will curl as it dries, will darken by the amount you measured in Part XVIII, and has three white specks where dust sat on the negative. Almost none of what follows is a matter of taste: the wash has a published sequence and a test that says whether you followed it, the drying method is a variable in a number you already measured, and the mounting decision has two Tier 1 sources that disagree — where the disagreement is worth more than either answer alone.

Three hours across two sittings, because a fibre print does not dry to order. Two prints leave it, one fibre and one resin-coated, washed by a sequence you wrote down first and proved afterwards, dried, flattened, trimmed, spotted and signed, and one of them mounted.

Purpose

To finish two prints to a standard somebody else could check: writing down a wash sequence before the first sheet goes into water, against the maker’s published optimum-permanence sequence for that paper; running it with the equipment you have; proving it with the residual-thiosulfate test Part XII established, and knowing what a clean result licences; drying by the method your dry-down figure was measured under; flattening without cracking the emulsion; spotting honestly; and mounting on materials whose specification you can name rather than whose marketing you have read.

Learning objectives

By the end of this session you will be able to:

• Write a wash sequence for a named paper, with times, temperatures and agitation, and defend every line against the maker’s published one.
• Say why a change of water beats a trickle, why a fibre base needs sixty times the wash of a resin-coated sheet, and what a washing aid does chemically that more water cannot.
• Run the residual-thiosulfate test on a print’s batch, name where it can and cannot be run, and state the claim it supports.
• Choose a drying method knowing what it does to image tone, to curl and to the dry-down correction you are already applying, and say what glazing is and what it costs.
• Explain why a fibre print curls and a resin-coated one does not, and why a damp print flattens where a bone-dry one cracks.
• Trim and spot a print, and say what spotting can and cannot honestly repair.
• Choose between hinges, corners, an over-mat and dry mounting, name the argument on each side, and say what board specification you bought against.
• Sign and label a print so the record survives its next owner.

Prerequisites

• The physics of washing, which owns diffusion, the arithmetic of a change of water and the mechanism of a washing aid. This page uses all three and re-derives none.
• Permanence and image deterioration, which owns sulfiding, silver mirroring, the standards the course can and cannot quote, and the enclosure priorities applied here.
• The wash testing lab, where you first ran the two spot tests, and the procedure you follow tonight.
• Developing the print consistently, which produced the session discipline the first hour depends on.
• Maximum black, base white and dry-down, which produced your dry-down figure under one drying method.

Safety classification

Level A throughout. Every solution is at tray dilution and room temperature; nothing is weighed from a jar, nothing heated beyond a press platen, nothing evolves a vapour. The classification follows the rubric on three criteria: no dry powder, no heated bath, no gas.

Two hazards are new to this part and neither is chemical. The dry-mounting press is the only hot mains appliance the course uses — certified, bought, operated closed, its platens at the temperature a mounting tissue activates at — and the trimming blade is the only cutting tool, used against a steel rule on a mat. Both arrive at the end of a long session, when attention is worst.

What is not a hazard here, and why. There is no dust exposure: no powder is opened, so the inhalation route that raises the developer-mixing lab to Level B is absent. There is no sulfur dioxide route, because the acid stop and the sulfite-bearing developer never meet in one vessel. There is no concentrated silver: what exists is locked in hardened gelatin or dissolved in spent fixer at an amateur bath’s concentration.

Two steps sit above Level A and are done separately. Weighing solid sodium sulfide is Level C, and making 1 per cent silver nitrate is Level B. Both stocks are made once under the controls the test procedure sets; here the reagents exist only as solutions dosed in drops. Without those controls, run neither test and record the fact — a blank in an evidence table is a failure, “not tested, no Level B controls available” is a decision.

Hazards

Hazard	Where it arises	Control
Skin sensitisation and eye irritation from an alkaline developer	The first hour, if you print rather than bring prints	Nitrile gloves, eye protection, one pair of tongs per bath
Silver nitrate: corrosive, stains skin black, very toxic to aquatic life	The residual-hypo test	Sealed goggles, gloves, tongs; the strip never touched; see the procedure
Sulfide meeting any acid, giving hydrogen sulfide	The residual-silver test near a stop or fixer tray	Layout, not care: reagents at opposite ends, separate waste
Hot platen and trapping edge	Dry-mounting or flattening press	Certified appliance, operated closed; hands clear; nothing wet near it
Blade injury	Trimming and mat cutting	Good light, steel rule, mat, free hand behind the blade line, blade retracted
Water on the floor near a mains appliance	Tray, siphon, press and enlarger in one room	Wet and dry sides separated; the press never on the wet bench
Slips carrying wet prints	Between wash and drying area	One route, cleared with the lights on, walked before it is used wet
Aquatic toxicity of spent fixer and the first wash	Clean-up	Collected under the silver-bearing waste procedure

Required PPE

Nitrile gloves on the wet side, changed the moment either test reagent touches them and again before you handle a dry print — a glove that has been in fixer is not a handling glove. Eye protection with side shields for tray work, and sealed splash goggles rather than spectacles for the silver nitrate step, which is classified as causing serious eye damage. One pair of tongs per bath.

For the dry half the protective equipment is different in kind and no less required. The Library of Congress asks for freshly washed hands and clean lint-free cotton or inert plastic gloves such as nitrile whenever a photograph is handled, no contact with the image surface, and an auxiliary support — acrylic, or two- or four-ply rag board — under any print that has to be moved or turned over. That protects the print rather than you, and it is the only control that stops the most avoidable defect in this part: a fingerprint in a margin you spent three hours earning.

Ventilation

An openable window or an extractor giving a through draught, checked with the ventilation check before you start. Airflow is not a vapour control here — no bath is heated and the most volatile thing on the wet bench is water. It is present for comfort and for one mechanical reason: a fibre print dries by evaporation into moving air, and a still, humid room is why squeegeed prints still take all night. The one genuine ventilation requirement is the sulfide test, and it is met by layout rather than by the fan — hydrogen sulfide is why the incompatibility matrix keeps sulfide and acid apart.

Materials

Item	Quantity	Note
Fibre-base variable-contrast paper, 8 × 10 in	3 sheets	Two prints, one control sheet; same box and weight
Resin-coated variable-contrast paper, 8 × 10 in	3 sheets	Two prints, one control sheet
The printing map from the previous lab	1	Tonight reproduces a print rather than invents one
Developer at your session dilution	1 L working	Same developer and age bracket as the map
Stop bath concentrate	50 mL	1+19, 1 L working
Rapid fixer concentrate, non-hardening	200 mL	1+4, 1 L working
Washing aid concentrate	200 mL	1+4, 1 L working; fibre only
Wetting agent	5 mL	1+200 final rinse
1 per cent silver nitrate, made separately	100 mL	Residual-hypo test
Diluted sulfide test solution, made separately	a few mL	Residual-silver test
Conservation-quality mount board, 4-ply	2 sheets	Buy against the standard, not the adjective
Backing or filler board	2 sheets	Same specification; it never touches the print and still matters
Japanese tissue and starch paste, or photo corners	2 hinges’ worth	The reversible attachments
Dry-mounting tissue	1 sheet	Only for the optional arm
Spotting dyes and a 000 or 0000 sable brush	1 set	Neutral and warm
Blotters, photographic grade	6 sheets	Not kitchen paper, which sheds
Soft pencil and a pigment-ink pen stating it passes the PAT	1 each	Signing and labelling

Chemicals

Nothing is mixed from powder. The quantities below are what is in the tray for the D-72 route at 1+4 in 1 L of each working bath, plus the two test reagents, which arrive already in solution.

Chemical	Quantity in the tray	Form and role
Ammonium thiosulfate	200 mL of concentrate	Rapid fixer at 1+4, non-hardening; what the wash exists to remove
Citric acid	50 mL of concentrate	Stop bath at 1+19
Sodium sulfite	200 mL of concentrate	Washing aid at 1+4; the open equivalent is the 1 per cent sulfite bath
Silver nitrate	1 g, as 100 mL of 1 % w/v	Residual-thiosulfate test; corrosive, stains skin black
Sodium sulfide	drops of a 1+9 dilution of 2 g in 125 mL	Residual-silver test; never near an acid
Calcium carbonate	at least 2 % w/w of the board	Not a reagent: the alkaline reserve in the board you buy

The wetting agent’s composition is not published and this table does not describe it: record the product and dilution, and note that it is proprietary. The same applies to a bought paper developer.

Equipment

Enlarger and timer for the first hour, from Part XVI and Part XVII. Four dishes with a pair of tongs each, plus a fifth reserved for the washing aid that has never held fixer. A thermometer, because the published sequence specifies the wash water’s temperature and not only the developer’s.

A wash arrangement is the piece of equipment this session is really about. Three are usable, and they differ in what they achieve rather than in what they cost.

Three wash arrangements, and what each actually controls

1. 1Tray, filled and emptied by hand — the most water-efficient arrangement there is, and worthless while two prints are stuck face to face
2. 2Tray siphon — converts a tray into continuous flow; water will short-circuit from inlet to siphon unless the prints are separated and moved
3. 3Vertical slot washer — buys separation, which is the variable that actually fails; costs a fixed capacity and a continuous flow

Drawn to compare what each arrangement controls, not to scale and not a construction drawing. Kodak's instruction for either kind of tray is the same one: agitate the prints, keep them separated, and do not overload the tank.

Also a squeegee or soft viscose sponge, a drying rack or blotter book, a flat weighted board or press, a steel rule, a self-healing mat, a sharp blade, and the viewing light you judge finished prints under.

Estimated cost

Band ££, and this is the page in the part where the band does real work, because most of what it covers is bought once and lasts for years: a slot washer, a press, a mat cutter, spotting dyes. What the session consumes is six sheets of paper and about four litres of solution. The planner holds the dated figures — and, for this part, mostly gaps.

Estimated consumables cost

Consumed	This session	Sourced price	Cost this session
RC paper, 8 × 10 in, variable contrast	3 sheets	£33.50 for 25 to £96.18 for 100	£2.88 to £4.02
Fibre-base paper, 8 × 10 in	3 sheets	£47.04 for 25 sheets to £150.28 for 100	£4.51 to £5.64
Paper developer concentrate or stock	100 mL, for 1 L at 1+9	£10.52 per 500 mL to £20.03 per 1 L	£2.00 to £2.10
Stop bath concentrate	50 mL, for 1 L at 1+19	£10.66 to £12.18 per 500 mL	£1.07 to £1.22
Rapid fixer concentrate	200 mL, for 1 L at 1+4	£21.05 to £25.98 per 1 L	£4.21 to £5.20
Wetting agent	5 mL, for 1 L at 1+200	£28.70 per 1 L	about £0.14
Washing aid concentrate	200 mL, for 1 L at 1+4	£17.99 per 1 L of concentrate; the file’s other washing-aid record is a powder, which is a different form	£3.60
Silver nitrate for the hypo test	1 g	£59.95 for 25 g to £112.90 for 10 g	£2.40 to £11.29
Mount board and backing board	2 sheets each	None. Board meeting ISO 18902 is a gap the overview names	—
Japanese tissue, starch paste or photo corners	2 hinges’ worth	None in the price file	—
Spotting dyes	a few drops	None in the price file	—
Dry-mounting tissue and press hire	1 sheet, and a day	Neither has a UK listing in the price file	—

The rows carrying numbers total about £21 to £33, a floor rather than a total by a wider margin than anywhere else in this part: four of the twelve rows have no sourced price, and they are the materials that carry the session past the wash — the board, the hinges, the dyes and the mounting tissue. The part overview states the gap in the same terms the price file uses for the ones it names, and until a conservation supplier’s dated listing exists no honest number belongs in those cells. Equipment is not in the table: a washer is not consumed.

Waste streams

Four, and they stay apart.

Alkaline developer, about 1 L, negligible in silver on Kodak’s figures, collected for its pH and aquatic classification. Acid stop, 1 L, in its own container. Silver-bearing: the spent fixer, the first wash of each paper, the spent washing aid, and the silver nitrate test solution with its rinse and strips, under the silver-bearing waste procedure. Sulfide, separately again, never into a container that has held stop or fixer.

Solids — gloves, blotters, trimmings, tested strips — are bagged, because a processed print carries silver in hardened gelatin. All under the disposal caveat.

Alternative route

The exposing half needs a room that can be blacked out, and there is no substitute. But this is where that matters least: from the fixer onwards everything happens in daylight, and the whole second sitting happens on a kitchen table.

Without a darkroom at all. Do not make the prints: finish your own from an earlier session, or two sheets of unexposed paper carried through the full sequence. The wash, the test, the drying comparison, the flattening and the mounting all run on a blank sheet, and the only arm you lose is spotting. Record which you ran, and on what.

Without running water. This is the constraint the arithmetic is kindest to. A change of water in a bucket beats a trickle from a tap, and Part XII prices the difference: one complete change is worth ln(1 + ρ) tank-volumes of running water, two to four for realistic carry-over. Fill a tray from a jug, agitate, tip it out, refill. Ten changes with separation beats ten minutes under a slow tap, in a room with no plumbing at all.

Without a slot washer. Tray-and-siphon and hand-changed tray both work, and what they fail on is separation. Wash two sheets in a 12 × 16 in tray rather than eight, shuffling bottom to top on a timer, because the published capacity figures assume it.

Without a dry-mounting press. Use the flattening route — the course’s default anyway — and mount by hinges. Wall recorded in 1912 that a flat-iron had been suggested for dry mounting and was “not a satisfactory substitute”, and nothing the course has read overturns that.

Without conservation board, do not substitute. Board is the one material here whose failure is invisible for a decade and then permanent, and there is no household equivalent to one meeting ISO 18902. Hinge the print into a folded sheet of the best paper you can specify, store it flat, and record the mounting step as deferred rather than improvised: a print in a plain folder is in better condition in twenty years than the same print glued to grey card.

Preparation

All of this before any paper is wet.

1. Write the sequence out first. One column for the maker’s published sequence, one for yours, one for the reason where they differ. This is the deliverable, not a formality: a wash you did not write down is one you cannot defend, repeat or diagnose. The two sequences the course holds for the commonest papers are below.

   Step	ILFORD MULTIGRADE FB CLASSIC, optimum permanence	ILFORD MULTIGRADE RC
   Fix	RAPID FIXER or HYPAM at 1+4, 1 minute	Rapid fixer at 1+4, 30 seconds
   First wash	Fresh running water, 5 minutes	—
   Washing aid	ILFORD WASHAID at 1+4, intermittent agitation, 10 minutes	Not used
   Final wash	Fresh running water, 5 minutes	Fresh running water, 2 minutes
   Temperature	18–24 °C including the wash water	Above 5 °C
   Standard alternative	Fresh running water, 30–45 minutes, above 5 °C	30 seconds vigorous, if speed matters more

   ILFORD attach three conditions as load-bearing as the times: do not add a hardener to the fixer, do not exceed its capacity and do not extend the fixing time, because all three make washing harder. The one-minute fix is not a shortcut; it is the reason the wash can be twenty minutes, not an hour.

2. Check the fixer’s running total against its published capacity before the session, not after. Kodak state that an exhausted fixing bath contains insoluble silver compounds that remain in the print and cannot be removed completely by washing. No wash recovers from that: it is a fixing failure the wash test cannot see, which is why the second test exists.

3. Cut and mark the control sheets. One unexposed sheet of each paper, the same weight and size as the prints, pencilled on the back, goes through every bath with the batch. Kodak Limited’s 1949 test is written around exactly this sheet, for the reason stage 4 makes plain.

4. Bring the wash water into the band. The fibre sequence specifies 18–24 °C including the wash water, and a January tap is nowhere near it. Draw and stand the water in advance, or mix it. Cold water does not merely slow the wash; it changes what the published times mean.

5. Decide the drying method now, and write it on the sheet. Skipping this costs people the number they measured in Part XVIII.

6. Lay the bench out. Wet and dry sides separated, the press well away from the trays, the two test reagents at opposite ends with their own droppers, tongs and waste.

Procedure

Two sittings, because a fibre print takes hours to dry and you cannot flatten what is still damp. Sitting one is about ninety minutes and ends with prints drying; sitting two is about ninety minutes the following day.

Sitting one, stage 1 — Print (about 30 minutes)

Make two prints from the previous lab’s printing map, one on fibre and one on resin-coated paper, at the base exposure and local moves the map records, corrected for your measured dry-down. If you brought finished prints, skip to stage 2 and note it.

Develop, stop and fix by the archival print SOP, with each paper’s control sheet in the batch. Fix to the published time and stop: 1 minute for fibre at 1+4, 30 seconds for resin-coated. Add each sheet to the fixer’s running total as it leaves.

Sitting one, stage 2 — Wash the resin-coated print (about 5 minutes)

Two minutes in fresh running water above 5 °C, prints separated, the water flowing fast enough to change completely inside the time. Kodak’s parallel figure is four minutes with a complete change of water during the four, plus an instruction that reads oddly until you know why: avoid overwashing.

That is not thrift. ILFORD give the mechanism: prolonged immersion causes edge penetration and print curl with resin-coated papers, and wet times longer than fifteen minutes are to be avoided. The polyethylene seals the faces of the base, not its cut edges, and given long enough water works in through the exposed core at the trim line. A resin-coated print left in the wash overnight is not cleaner; it is damaged.

Do not put a resin-coated print in the washing aid. Kodak state that Hypo Clearing Agent is not recommended with resin-coated papers, and the reason is arithmetic rather than incompatibility: an RC sheet already washes in four minutes because the thiosulfate never entered the base, so an exchange bath has nothing to reach.

Sitting one, stage 3 — Wash the fibre print (about 25 minutes)

Run the sequence you wrote in preparation step 1. For the optimum-permanence route that is five minutes in fresh running water, ten in the washing aid at 1+4 with intermittent agitation, and five more in fresh running water, all between 18 and 24 °C. Three details decide whether it works.

Separation. Kodak ask you to agitate the prints, keep them separated and not overload the tank; Reilly is blunter — with imperfect apparatus, “hand agitation of the prints is absolutely necessary”. Two fibre sheets face to face are one thick sheet with no water between them, and the timer keeps running regardless.

The washing aid’s capacity, which is small. ILFORD give 40 sheets of 8 × 10 in fibre paper per litre, and a litre lasts seven working days; Reilly’s figure for a 1 per cent sulfite bath is no more than 20 such prints per litre. Exceed it and the bath is a soak.

The first wash is not optional. The aid exchanges ions rather than dissolving thiosulfate, so its target is the last, slow, tightly held fraction. Carry free fixer into it and one print exhausts it.

Sitting one, stage 4 — Prove it (about 15 minutes)

Take the fibre control sheet from the final wash wet and run the residual-thiosulfate test by the procedure: cut it in two, immerse one half in 1 per cent silver nitrate for about three minutes, rinse, and compare it wet against its own untreated half in subdued light. No colour difference means the thiosulfate has gone; a yellow-brown tint means it has not. Repeat on the resin-coated control sheet, then run the sulfide test on a white margin of each print against a reference spot on a sheet you know to be well fixed.

!Where on the sheet you can test, and what a clean result licences

The thiosulfate test cannot be run on a print you intend to keep. As published it requires a strip cut off and immersed for three minutes in a corrosive silver salt — which is why Kodak Limited’s 1949 directions build it around an unexposed control sheet of the same weight and size processed with the batch, and why this session cuts two.

The silver test can be run on the print, being a drop blotted off within seconds, and it goes on a white area outside the image — the margin, not the picture. ILFORD are explicit that the print must be well washed first: the test is not effective straight from the fixer, where free thiosulfate holds the silver the sulfide is looking for. A reading taken there is no reading.

What a clean result licences. That an unexposed sheet of the same paper, in the same batch and water, showed no visible colour change under this reagent and this comparison. That is a real claim. It is not a figure in micrograms per square metre, and this course prints no threshold from any standard because it has read none: the ISO method usually cited, ISO 18917, is named in no document in the corpus, and what the corpus carries is its ancestor ANSI PH4.8-1985, from the Library of Congress’s standards bibliography. Part XII sets this out in full and states the course’s own criterion in public, which makes the claim checkable.

And two false positives are on the record, both in the troubleshooting table: Kodak Limited’s footnote that the tint can instead come from hydrogen sulphide or wood extracts in the water supply, and the dark ring a sulfide spot leaves if it is allowed to pool and dry.

Sitting one, stage 5 — Final rinse and dry (about 15 minutes, then hours)

Give both prints a final rinse in wetting agent at 1+200 — immerse completely for a few seconds, the time is not critical, and drain. ILFORD’s claim for it is narrow: it aids rapid and even drying and reduces drying marks. It does not clean or preserve, and it is not part of the wash. It lowers surface tension so the water film breaks up evenly instead of beading and leaving a boundary where it dried last. Measure it — too little and too much both give uneven drying — and do not agitate it hard, because it foams.

Squeegee both faces, then dry by the method you wrote down in preparation step 5.

Method	What the makers publish	What it costs
Flat on a rack	ILFORD and Foma: air-dry, freely laid, at room temperature	Slow for fibre; a fibre print curls hard
Clipped back to back	ILFORD: clip prints back-to-back to minimise curl	Halves rack space; both prints must be the same paper
Between blotters	Kodak: dry fibre prints slowly between blotting paper or on a rack	Slowest, flattest; needs clean blotters
Warm air	Kodak: below 88 °C (190 °F) from a hair dryer; ILFORD and Foma: machine air to 85 °C	Fast; shifts image tone, see below
Glazed or ferrotyped	ILFORD: fibre may be glazed; never resin-coated	High gloss; laborious; see below

!Heat is not a neutral way to remove water

Kodak state it plainly: drying with heat causes a shift to a cooler tone with some paper and toner combinations, and their remedy is the dryer’s lowest speed and temperature settings with the toning adjusted to compensate. The drying method is a variable in the appearance of the result, not only in the time it takes.

It is also a variable in your dry-down figure. Part XVIII measured dry-down under one drying method and said so; air on a rack, heat, a blotter book and a glaze do not leave the same dried surface, and the surface is half of a reflection reading. Change the method afterwards and the correction belongs to a print you are no longer making. Hold the method fixed, or measure again.

Sitting one, stage 5a — Glazing, if you want the high-gloss surface

Glazing — ferrotyping — is drying a wet fibre print against a polished surface so the gelatin sets on it and takes a mirror gloss. Nothing chemical happens: the image is unchanged, and only the way the surface scatters light alters, reflecting more specularly and scattering less back out of the shadows, so the blacks look deeper. ILFORD list it as one of three finishes for their fibre paper, after the same squeegee and wetting-agent rinse.

Wall’s 1912 description is still the procedure: squeegee the print face down on to a polished ferrotype plate of thin enamelled iron, or stout glass released with French chalk, wax or paraffin, floating it on under water so no air-bells are trapped.

What it costs is time and yield, which is why it is now rare. Plates must be polished before every use, a speck prints as a blemish, and Wall names the characteristic failure: drying must not be hurried, because a print that dries at the edges peels there while the centre is wet and comes away bearing an oyster-shell mark. The period’s answer was formalin hardening, which this course does not teach — formaldehyde’s hazards are out of proportion to a surface finish. Meanwhile resin-coated paper gives a gloss out of the box, and must never be glazed: ILFORD and Foma both state that resin-coated papers must not be glazed, ferrotyped or dried on a drum or flatbed glazer, because the polyethylene can stick.

Sitting two, stage 6 — Flatten (about 30 minutes of work, spread over a day)

A dry fibre print curls, usually towards the emulsion, and Part XVIII’s section drawing shows why: a thick absorbent core carrying a thin gelatin layer on one face only. Both swelled in the wash and both shrink as they dry, by different amounts, and the sheet resolves the mismatch by bending. A resin-coated sheet does not, for the same reason inverted: polyethylene seals both faces, its core never took up water, and nothing in the base can shrink.

Flattening is not pressing a dry print flat. It is putting a controlled amount of water back, letting the fibres relax, and drying under restraint. Three routes:

• Weights and boards. Face up between clean blotters under a flat board and weight, for a day or two. Slowest and safest: the print goes on losing moisture through the blotters while held flat.
• A press used as a flattening press. Dry heat and pressure with no tissue — the print between clean release paper at a low setting, in and out in seconds, then straight under a cold weight. Foma publish the equivalent: hot air at a maximum of 85 °C and subsequently pressed, or dried stretched at a maximum of 35 °C.
• Humidification and slow drying. For a badly curled print, raise the humidity around it slowly in a closed box with damp blotters that do not touch it, then dry it flat under weight. This is what recovers a rolled print, and the Library of Congress says why you would need it: a rolled photograph may crack when it is unrolled.

✕The crack, and the warning it is giving you

Force a bone-dry, hard-curled fibre print flat under a cold weight and a fine crack appears, usually running with the curl, in the gelatin and sometimes the baryta beneath. It is not repairable, and it is not a spotting problem.

Dry gelatin behaves as a glass rather than a rubber: below a certain moisture content it has no give, and bending strain at the emulsion surface is relieved by fracture instead of deformation. A damp print flattens because the gelatin still holds water and can flow; a dry one fractures because it cannot. Hence the rule, from the mechanism rather than from lore — add moisture before you add force. A print that resists is reporting that it is too dry.

Sitting two, stage 7 — Trim and spot (about 30 minutes)

Trim against a steel rule on a mat, in good light, with a fresh blade, after the print is flat and not before. Wall’s 1912 order is still right: straighten, then trim, then consider the mount.

Then spot. Load a 000 or 0000 sable brush, discharge most of it on scrap, and build the mark up from light to dark in many small touches, matching the tone around it rather than the tone you think it should be, under the light the print will be seen in. Neutral dye on neutral paper, warm dye on warm-tone: a black spot on a warm-black print reads as a hole.

!What spotting can and cannot honestly repair, and what the course can source

It repairs white specks. A dust speck on the negative prints as a clear spot, and darkening it to match its surroundings adds nothing that was not in the scene.

It does not repair black marks, because dye only darkens: those need local bleaching, which belongs to the reducers and carries its own hazard assessment. It does not repair a scratch through the emulsion, only its appearance from one angle. It does not repair a badly printed area, and using it to try is where retouching becomes a substitute for reprinting.

On sourcing, plainly. The technique above is photographic convention and experiential recommendation, not manufacturer data: no data sheet for a modern spotting dye is in this course’s corpus, and no brush size or sequence here can be cited to one. What can be cited is that the operation is expected of the material — ILFORD state that MULTIGRADE FB CLASSIC responds to the usual techniques of toning, chemical reduction and retouching — and that it is old: Wall’s 1912 dictionary lists bromide pencils as “special pencils for retouching, spotting out and working up bromide prints and enlargements”.

Sitting two, stage 8 — Mount (about 30 minutes)

Mount one print; the other stays in a folder as the control you will want when you judge the mount.

A frame package, in section

Drawn from the frame package the Image Permanence Institute describes. Depths are readable rather than to scale. Layer depths are drawn to be readable, not to scale: on real film the base is roughly a hundred times the emulsion, and drawn honestly the emulsion would vanish. Any thickness given in the labels is the real one.

The reversible methods, and why they are the default.

• Hinges. Two of Japanese tissue and starch paste, along the top edge only — IPI name this as the method that works best for fragile photographs. The print hangs, so it moves with humidity without buckling, and both print and board can be recovered.
• Corners. Of an inert plastic such as polyester, or of high-quality paper, with acid- and rubber-free adhesive. IPI note that corners work well with sturdy, undecayed photographs.
• An over-mat, which attaches nothing: the window mat holds the print by covering its edges. The Library of Congress calls a mat an excellent storage method, giving a great deal of protection from physical damage and some from pollutants and environmental fluctuation — and is equally clear that mats are expensive, slow to make and greatly increase the storage space needed.

Dry mounting tacks heat-activated tissue to the back of the print, trims it with the print, positions it and presses it. It bonds the whole back to the board and gives a flatness nothing else achieves.

⁇Whether to dry mount at all: two Tier 1 sources, both right about different things

ILFORD’s position. MULTIGRADE FB CLASSIC “can be mounted using the standard techniques for fibre base papers”, and the parallel sheet says the same for the resin-coated range. Heat mounting is among those techniques. ILFORD are describing what the material tolerates.

IPI’s position. Heat mounting, spray-adhesive mounting and pressure-sensitive tapes are not recommended for preservation framing, because they are not easily removable, and it is best to choose a method that can be undone so the print can be reframed and the materials reused. IPI are describing what a collection should accept. The Library of Congress agrees from the other end: self-stick tape marked “archival” can be extremely difficult to remove and often creates condition problems, and historical mounts were frequently acidic — when such a mount became brittle, the image itself was at risk from breakage.

Both are Tier 1 and neither is wrong, because they answer different questions: will the paper survive the process, and should a photograph be permanently attached to anything.

What this course teaches. Hinging is the default; dry mounting is a choice with its cost stated, and the cost is reversibility — print and board are one object thereafter, and every later decision inherits that. Dry mount only because flatness matters more to this print than that option does, and write the decision and its reason on the label.

⚠Heat, resin-coated paper, and a comparison the course is making itself

What the tissue makers publish. Drytac give an activation temperature of 90–99 °C (194–210 °F) for their permanent dry-mounting tissue and 85–99 °C (185–210 °F) for their heat-activated film, both sold for photo framing. Neither page states a dwell time, a pressure, or anything about resin-coated photographic paper — the compatibility question a printer actually has.

What the paper makers publish. ILFORD cap hot-air drying of MULTIGRADE RC at 85 °C and state that resin-coated papers must not be glazed, ferrotyped or dried on a drum or flatbed glazer because the polyethylene can stick to the glazing surface. Foma give the same ceiling for FOMASPEED, and Kodak’s figure for warm air on a print is below 88 °C (190 °F).

The comparison is the course’s own, made across two sets of manufacturer figures because no maker answers directly: the tissues’ activation band starts at the top of, and runs above, the maximum drying temperature the resin-coated paper makers publish — and polyethylene softening against a hot surface is the mechanism they warn about. A press platen is a hot surface with pressure behind it.

What follows, as inference and not a ruling. The course gives no actionable dry-mounting procedure for resin-coated paper. Dry mount the fibre print; if you insist on the resin-coated one, test on a spoiled sheet from the same box and expect to lose it. Historical practice ran in the same band and is no evidence of safety for a material that did not then exist: Wall’s 1912 account has the platens at about 200 °F (93 °C), and in 1912 every print was fibre.

Sitting two, stage 9 — Specify, sign and label (about 15 minutes)

Buy board against a specification, not an adjective. IPI are blunt: “acid-free”, “archival”, “museum-quality” and “conservation board” are marketing terms, neither standardised nor legal. Look instead for the claim that the material meets ISO 18902, which requires every component to pass the Photographic Activity Test (ISO 18916) and adds the rest: paper and paperboard at pH 7.0 to 9.5, an alkaline reserve of at least 2 per cent calcium carbonate, lignin-free stock at a Kappa number of 7 or below, a colorant-bleed test for coloured board, no post-consumer recycled paper, neutral or alkaline sizing. A material passing only the PAT, or only the pH test, is not necessarily photo-safe.

⚗Buffered or unbuffered, and why the answer is process-specific

The alkaline reserve is a sacrificial store of calcium carbonate that neutralises acid arriving from the air, the print or the board itself. IPI note the limit: it is consumed as it reacts, so its useful life is finite.

For a silver gelatin print, buffered is the recommendation. The Library of Congress lists the materials buffered paper may be used with, and silver prints are on it, with platinum and chromogenic prints, acetate and nitrate films, and prints mounted on acidic boards.

It is not a universal answer, which is why it is asked per process. The same passage recommends unbuffered paper, at pH 6 to 7, for cyanotypes and architectural drawings — and Part XXI’s Prussian blue is exactly that chemistry. “Buffered is better” would be wrong in the one place the source is explicit.

And the enclosure is not the first lever. IPI’s priority is worth repeating: enclosures cannot overcome deficiencies in the storage climate, and improving the climate is more effective overall.

Sign in soft pencil in the margin or on the mount. For anything that must not smudge or fade, use a pigment-ink pen that states it passes the Photographic Activity Test — the Library of Congress names exactly that, and warns off ink and felt-tip pens on originals in the same breath as pressure-sensitive tape.

The label goes on the back of the frame or folder, and IPI’s list costs nothing to complete: what the picture is, when it was made, who made it, when and by whom it was framed. Add what nobody else can reconstruct — paper and batch, developer and dilution, the printing map’s version, the wash sequence and the two test results.

Expected observations

In the wash. The first change of water is visibly the busiest: on a fibre sheet you can often see schlieren — refractive streaks — coming off in the first seconds and not later. That is carried fixer leaving, and it is why the first wash and the spent fixer share a waste container.

In the wash aid, nothing visible: the exchange is between ions in solution and ions in the fibres, with no colour, precipitate or smell, and the only evidence is the test at the end.

In the test. A well-washed control sheet gives no perceptible difference between its treated and untreated halves, wet, side by side under one light. A poorly washed one gives a yellow-brown tint, obvious once you have seen a matched pair. A sheet that darkens all over in seconds is carrying free fixer.

In drying. A fibre print curls towards the emulsion and goes on curling after it feels dry. A resin-coated print dries in ten to twenty minutes and stays roughly flat; if it curls hard or shows a swollen edge, look at the wet time.

In flattening, a print under blotters and weight is flatter after an hour and not finished after four, while a press-flattened print comes out warm and limp and curls again as it cools unless it goes straight under a cold weight. In spotting, your first spot will be too dark.

What is happening chemically

Washing is diffusion, and the only variable you control is the gradient. Part XII derives it; this page uses the result. Flux depends on the diffusion coefficient, the area and the concentration gradient, and only the last is yours, kept steep by holding the concentration in the water near zero. A print in water it has equilibrated with is soaking, not washing — which is why a complete change beats a trickle, priced by Part XII at ln(1 + ρ) tank-volumes of running water per change.

Fibre holds thiosulfate where an exchange bath has to reach it. The difference between the papers is not bulk but which layers hold solution. In a resin-coated sheet, polyethylene seals both faces of the core, so solution never enters it and the thiosulfate’s journey is back out through the emulsion — micrometres. In a fibre sheet the base is a reservoir of matted cellulose, and the ion must leave the fibres, cross the baryta and pass the emulsion. Kodak Limited’s 1949 handbook puts it in the language of the period: traces of hypo are tenaciously held by the paper fibres. Reilly is stronger, and this is why a washing aid exists at all — with prints the rate of washing slows down tremendously at low thiosulfate concentrations, and in practice it is impossible to remove every trace of thiosulfate simply by washing in water.

A washing aid is an exchange, not a solvent. ILFORD describe WASHAID as aiding removal of the thiosulphate by-products of fixation by ion exchange; Reilly gives the mechanism generically, the treatment displacing absorbed thiosulfate ions and replacing them with less harmful, more soluble ones. Nothing is destroyed: thiosulfate bound to the fibres returns to solution where the final wash can carry it away, and something innocuous takes its place on the binding sites. That is why the aid shortens the wash rather than replacing it, why the first wash comes first, and why its capacity is small. It is not a hypo eliminator, which oxidises residual thiosulfate and which the course does not use: Kodak put HE-1 after a thirty-minute wash and before a further ten.

Two fixing decisions are really washing decisions. A hardener cross-links the gelatin, and a cross-linked gel swells less and lets ions out more slowly, which is the mechanism behind ILFORD’s flat statement that a hardening fixer reduces washing efficiency. Over-fixing expands the paper and lets the solution penetrate the base, where Kodak say trapped fixer is difficult to remove — so an over-fixed fibre print begins its wash with thiosulfate in the one place washing reaches worst. The one-minute fix and the twenty-minute wash are a single design, not two independent numbers.

What is left behind, and what it does. Part XII’s deterioration page owns the mechanisms; in short, residual thiosulfate supplies labile sulfur that converts image silver to silver sulfide and yellows the print generally, while residual silver — a fixing failure — stains the highlights and borders where the unexposed halide was. The faults are differently distributed because their causes are, which is why this session runs two tests and not one.

The mount board is chemistry too. Its calcium carbonate reserve consumes acid before it reaches the print, and lignin is excluded because it generates oxidisers, reducers, acids and chromophores as it ages. IPI publish the consequence as a photograph: a print whose edges, covered by a poor mat, went to silver mirroring while the oval the window left uncovered stayed clear.

Data to record

One row per print, in the lab notebook format.

Field	Why it is there
Date, paper, box and batch	A wash sequence belongs to a paper, not to a photographer
Printing map version	Ties the print to the exposure that made it
Fixer: dilution, time, running total before and after	Capacity is the failure the wash test cannot see
Wash sequence as run: step, time, temperature, agitation	This is the deliverable
Wash arrangement, and how many sheets at once	Capacity figures assume separation
Wash aid: dilution, time, sheets through this litre	Forty 8 × 10 per litre; seven days
Thiosulfate result, in words, on the control sheet	“No difference by eye, daylight, both wet” is data; “passed” is not
Silver result against the reference spot	And which paper the reference was made on
Final rinse: product and dilution	Because it is proprietary
Drying method, in enough detail to repeat	Temperature too, if heat was used
Does that method match the one dry-down was measured under?	The field people leave blank and regret
Flattening route, and hours under weight
Mounting method, board, and the packet’s specification claim	“Meets ISO 18902”, or honestly what it did say
Anything not tested, and why	A stated gap is evidence; a blank is not

Analysis

First, what does a clean result cover? A claim about the batch that sheet travelled with, in that water, on that day — not next month’s batch, a different paper weight, or a print that shared the tray with three others stuck to it. If the two control sheets disagree they are testing two different washes, and the interesting case is the resin-coated one failing, which usually means it never got separated.

Second, was it the wash or the fix? A yellow thiosulfate result with a clean sulfide result is a washing failure: more water, better separation, or an exhausted aid. A yellow sulfide result is a fixing failure no washing corrects — ILFORD’s remedy is a five-minute soak and the recommended fixing and washing sequence again in fresh fixer. If both are yellow, suspect the fixer’s running total.

Third, account for every difference from the published sequence. Forty-five minutes of running water instead of the wash-aid route is a published alternative and should be named as one. Twenty minutes is on neither maker’s sheet, and the test is then your only evidence — which is what the test is for, but write it as what it is.

Fourth, judge the mount as a decision rather than a finish. Beside the unmounted print, under one light: does the board’s tone push the picture warm or cold, and — the question that matters in ten years — could this print come off this board undamaged? If not, the label should say why that was worth it. The critique assignment owns the rest of that judgement.

Troubleshooting

What you see	Most likely cause	What to do
Yellow-brown tint on the thiosulfate strip	Wash did not reach the fibres: too short, still, cold, or sheets stuck together	Rewash the full sequence, separated, at 18–24 °C; retest
Whole strip darkens in seconds	Free fixer rather than traces: no first wash	Rewash from the start; check the batch had a first wash
Thiosulfate tint on a sheet you washed thoroughly	Kodak’s footnote: hydrogen sulphide or wood extracts in the water	Run the reagent on a sheet that never met a fixer; if that tints, the water is the variable
Sulfide spot yellow on the print, clean on the reference	Under-fixed, or exhausted fixer	Soak 5 minutes, refix and rewash in fresh fixer; retire the old bath
Sulfide spot dries into a dark ring	The blot was late	Repeat on fresh white margin, blotting within seconds
Uneven drying marks on a fibre print	Wetting agent too weak or too strong, or the print not squeegeed	Measure the dilution; ILFORD say both errors give this fault
RC print with a soft, swollen or delaminating edge	Edge penetration past about fifteen minutes wet	Shorten the wet time; this print’s damage is not reversible
Fibre print cracks when flattened	Flattened bone-dry and cold	Humidify slowly, flatten damp under restraint; the crack cannot be repaired
Flat in the press, curled again in an hour	Taken out warm and left to cool free	Straight from press to a cold flat weight
Print stuck to a glazing plate, or an oyster-shell mark	Drying hurried: edges dried and peeled while the centre was wet	Wall’s 1912 remedy is the only one — dry much more slowly
RC print stuck to a glazing plate or drum	It should never have been there	ILFORD and Foma both forbid glazing RC; the polyethylene sticks
Print cooler in tone than the ring-around	Heat drying	Kodak state the shift; dry cooler and slower, or adjust the toning
Spots visible from one angle only	Dye sitting on the surface rather than matching the tone	More, weaker touches; judge under the display light
Mat board yellowing the margin after months	Board bought on “acid-free” rather than against ISO 18902	Take the print off the board; buy against the standard

Clean-up

Prints out first, then reagents, then trays. Rinse the wash-aid dish separately and never use it for fixer: a dish that has held fixer has no business holding an exchange bath whose job is to be free of thiosulfate.

Blades retracted and put away before the bench is wiped, because a blade left out in a tidy-up is the likeliest injury here. Spotting brushes rinsed and shaped to a point; a sable brush dried splayed is finished. Blotters used on a wet print hold what they absorbed. Wipe the press platens cold and dry, and check no tissue has adhered.

Storage

The prints. Flat, in a folder or mat, in a box, in the coolest and driest room you have. Anything larger than 8 × 10 in is shelved horizontally; stored vertically, fill the box snugly or use a spacer, since a slumped print acquires a permanent bend. Rolling is the one thing to avoid: a rolled photograph may crack when it is unrolled.

The enclosures. Paper and plastic fail differently: paper abrades a print that is handled often, plastic can adhere to one above about 80 per cent relative humidity. Plastic should be polyester, polyethylene, polypropylene, spun-bonded polyolefin or polystyrene, with no fillers, coatings or UV absorbers, and never PVC or acetate. Everything in contact with the print passes the PAT.

The solutions. Washing-aid concentrate keeps four years full and airtight, six months half-full, seven working days at working strength. Date the bottle when you dilute it: an aid past its life is a soak that looks like a treatment. The board and tissue keep flat, dry and dark, away from anything that outgasses.

Disposal considerations

Spent fixer and the first wash carry dissolved silver as thiosulfate complexes, which is why silver recovery exists as a subject. The washing aid carries the thiosulfate it exchanged out of the paper and joins that stream; so do the silver nitrate solution, its rinse and the treated strips, the most concentrated silver in the session.

The sulfide solution goes to its own container, and the reason is a gas: Kodak state that sulfide discarded with a stop bath or a fixing bath generates hydrogen sulfide, which is toxic and will also fog paper and oxidise silver images in the room.

Board trimmings, blotters and gloves are ordinary solid waste unless wet with fixer, when they are bagged with the silver-bearing solids. Blades go to a sharps container, or taped inside their packaging so nobody meets an edge in a bin bag.

Local regulation governs all of it. The chemistry says what the streams are, not what your authority permits. ILFORD advise a UK domestic user to take used chemistry to a household waste and recycling centre. The disposal page carries the caveat in full.

Questions

1. A fibre print is fixed for four minutes “to be safe”, then washed the full forty-five. Using the makers’ statements, explain why it is likely to be worse washed than one fixed for one minute and washed for twenty.
2. Your wash-aid bath has had thirty-eight 8 × 10 fibre prints through one litre and was diluted nine days ago. Give two independent reasons to discard it, and say which the thiosulfate test catches.
3. A resin-coated print shows a swollen edge and slight delamination at a corner. Name the mechanism, the number exceeded, and why more washing will not help.
4. You dry test prints on a rack and exhibition prints in a warm-air dryer. Name two things that invalidates, and what would make both routes usable.
5. The control sheet’s thiosulfate test is clean and the sulfide spot on the margin is yellow. What has failed, what has not, and what is the published remedy?
6. A board is sold as “archival, acid-free, museum quality”. State what those words establish, and write the sentence you would look for instead.
7. You want a print perfectly flat and are considering dry mounting. State both arguments, name a source for each, and say what the label would have to say.
8. A friend proposes drying resin-coated prints on a flatbed glazer. Give the manufacturer’s statement, the mechanism, and the temperature comparison that makes a press platen a related risk.

Further experiments

Price the two wash routes. Run the wash-aid sequence and the forty-five-minute running-water sequence on two halves of one batch, metering the water with a bucket and jug. Test both, and report litres per print against the result. The course holds no data for this, and a dated answer for a named paper would be worth publishing.

Test whether separation is the dominant variable. Wash four fibre control sheets under one sequence: two separated and shuffled, two deliberately left stuck face to face. Test all four. The hypothesis is that separation matters more than the gap between any two published sequences, and an evening can falsify it.

Measure dry-down against drying method. Run Part XVIII’s arm 4 three times on one paper — rack-dried, blotter-dried, warm-air dried. If they differ measurably, the dry-down figure belongs to a method and every printing map should name it. If not, you have a useful negative result.

Find the moisture content at which your paper cracks. On spoiled prints only, dry fibre sheets to different equilibrium moisture contents — hours in a dry room, a day, a week over silica gel — and flatten each under the same weight. Record which crack. That is a rule for your paper in your climate, which beats general advice about “damp”.

Run the enclosure comparison the course cannot. On a print you can afford to lose, mat half under a board bought against ISO 18902 and half under one bought on the word “acid-free”, store both together for a year, and look at the margins. IPI’s oval-window photograph is what you are looking for.

Recap

• The wash sequence is written before the first sheet is wet. ILFORD’s optimum-permanence route for fibre is a one-minute fix, five-minute wash, ten minutes in WASHAID and five-minute wash, at 18–24 °C including the wash water, no hardener, no extended fixing. Resin-coated washes in two to four minutes and must not be over-washed.
• Changes of water beat a trickle, separation beats equipment, and the aid works by ion exchange rather than by force — which is why it shortens the wash and cannot replace it.
• The thiosulfate test goes on a control sheet, not on the print, being destructive as published; the silver test goes on a white margin, after washing. A clean result licenses a claim about that batch, not a figure in micrograms.
• Drying is a variable, not a delay. Heat shifts image tone on some paper and toner combinations, and the method is part of the dry-down number measured in Part XVIII. Glazing is a surface rather than a chemistry, and is forbidden on resin-coated paper.
• Fibre curls because a gelatin layer on one face of an absorbent base shrinks more than the base; resin-coated does not, because its base never wetted. Flatten damp and under restraint.
• Hinges and corners are reversible; dry mounting is not, and both Tier 1 positions are right about different questions. Buy board against ISO 18902 rather than against the word “archival”, and remember that buffered is right for a silver print and wrong for a cyanotype.

Check your understanding

Question 1. A printer fixes fibre prints for five minutes in a fresh non-hardening fixer, then washes them for a full hour in running water. Why might these prints be worse washed than prints fixed for one minute and washed for twenty?

• They will not be: an hour of washing removes more thiosulfate than twenty minutes under any circumstances
• Because prolonged fixing expands the paper and lets the solution into the base, and fixer trapped in the base is the hardest to remove
• Because a fresh fixer is more concentrated, so more of it is carried into the wash
• Because the extra four minutes exhausts the fixer, leaving insoluble silver compounds in the print

Show the answer and why

Answer: Because prolonged fixing expands the paper and lets the solution into the base, and fixer trapped in the base is the hardest to remove

Kodak give the chain explicitly: prolonged fixing expands the paper and allows the solution to penetrate the base, and fixer trapped in the base is difficult to remove. ILFORD reach the same conclusion from the other direction, warning that extending the fixing time makes washing more difficult. The wash cannot undo it, because the paper core is exactly where washing is slowest — which is the same reason a fibre print needs a wash aid at all. The short fix and the short wash are one design, not two independent numbers you can adjust separately.

Question 2. Your fibre control sheet shows no colour difference on the silver nitrate test. Which of these claims does that result actually support?

• That the print contains less residual thiosulfate than the ISO limit for optimum permanence
• That an unexposed sheet of the same paper, washed in the same batch and water, showed no visible change under this reagent and comparison
• That the print will not yellow in storage
• That both the fixing and the washing were adequate

Show the answer and why

Answer: That an unexposed sheet of the same paper, washed in the same batch and water, showed no visible change under this reagent and comparison

The test is a visual comparison with a threshold set by your eye, run on a control sheet rather than on the print, and it says what it says: no perceptible difference, on that sheet, in that batch. It is not a measurement in micrograms per square metre, and this course prints no limit from any standard because it holds none — the ISO method usually cited, 18917, is named in no document in the corpus, and only its ANSI ancestor PH4.8-1985 appears, in the Library of Congress bibliography. It also says nothing about fixing, which is the second test's job: residual silver is a fixing failure and shows in the highlights, not the general tone.

Question 3. Why does ILFORD tell you not to add a hardener to the fixer in the optimum-permanence sequence?

• Because hardener reacts with the washing aid to form an insoluble precipitate
• Because a hardener cross-links the gelatin, which then swells less and lets ions diffuse out more slowly, so washing efficiency falls
• Because hardened gelatin cannot be spotted or retouched afterwards
• Because the hardener leaves an alum residue that shows as a white bloom when the print dries

Show the answer and why

Answer: Because a hardener cross-links the gelatin, which then swells less and lets ions diffuse out more slowly, so washing efficiency falls

ILFORD state the effect — a hardening fixer reduces washing efficiency — and the mechanism is the gelatin. Cross-linking makes the gel swell less and diffusion out of it slower, so the thiosulfate that must leave takes longer to leave. It is a genuine trade: a hardened emulsion is tougher when wet, which matters in a machine and matters much less to a print that will be dried flat by hand. On a print you intend to keep, ILFORD resolve the trade in favour of washing, and provide non-hardening fixers so that you can.

Question 4. A print made yesterday on resin-coated paper is left in the wash tray while you eat dinner, about forty minutes. What is the risk, and why will the drying method not rescue it?

• None; RC paper is waterproof, which is the whole point of the polyethylene
• The emulsion will over-swell and reticulate, which careful drying can partly disguise
• Edge penetration: water works in through the cut edges, where the paper core is exposed, and the resulting swelling and delamination is not reversible by drying
• The image will bleach, because prolonged washing removes silver as well as thiosulfate

Show the answer and why

Answer: Edge penetration: water works in through the cut edges, where the paper core is exposed, and the resulting swelling and delamination is not reversible by drying

The polyethylene seals the faces of the base, not the edges the trimmer made. ILFORD state the consequence directly: prolonged immersion can cause edge penetration and print curl with resin-coated papers, so wet times beyond about fifteen minutes are to be avoided. Kodak's "avoid overwashing" beside a four-minute figure is the same instruction. Once water has entered the core and lifted the coating at an edge, drying removes the water and leaves the damage.

Question 5. You measured your paper's dry-down on rack-dried prints in Part XVIII. Tonight you dry the finished print in a warm-air dryer to save time. What have you actually done?

• Nothing of consequence: dry-down is a property of the paper and developer, not of the drying method
• Applied an exposure correction measured under a different drying method, and separately risked a shift in image tone that Kodak state occurs with heat on some paper and toner combinations
• Invalidated the printing map, which will now have to be remade from the test strips
• Reduced the dry-down, because heat drives more water out and the print therefore darkens less

Show the answer and why

Answer: Applied an exposure correction measured under a different drying method, and separately risked a shift in image tone that Kodak state occurs with heat on some paper and toner combinations

Two independent problems. First, the correction: air on a rack, heat, a blotter book and a glaze do not leave the same dried surface, and the surface is half of a reflection reading, so a dry-down figure belongs to the method it was measured under. Second, the tone: Kodak state that drying with heat causes a shift to a cooler tone with some paper and toner combinations, and tell you to use the lowest speed and temperature settings. Neither is catastrophic, and both are avoidable by writing the drying method on the printing map and holding it fixed — or by measuring the figure again for the new method.

Question 6. A hard-curled fibre print is put under a heavy flat board straight from the drying rack, and a fine crack appears in the emulsion. What does the crack tell you?

• That the paper was faulty, since a properly coated emulsion does not crack under a flat weight
• That the print was still damp, and the water in the gelatin caused it to swell against the board
• That the gelatin was too dry to deform, so the bending strain went into fracture instead: moisture should have been added before force
• That the board was not flat, so the load was concentrated along one line

Show the answer and why

Answer: That the gelatin was too dry to deform, so the bending strain went into fracture instead: moisture should have been added before force

Dry gelatin behaves like a glass rather than a rubber: below a certain moisture content it has no give, and a bending strain at the emulsion surface is relieved by fracture rather than by flow. That is why flattening is not "pressing a dry print flat" but putting a controlled amount of water back, letting the fibres relax, and drying under restraint. A print that resists the weight is reporting that it is too dry, and the correct response is humidity and time rather than more force. The crack itself cannot be repaired, and it is not a spotting problem.

Question 7. ILFORD say their fibre paper "can be mounted using the standard techniques for fibre base papers"; the Image Permanence Institute say heat mounting is not recommended for preservation framing. How should a printer read this?

• IPI is a conservation body and outranks a manufacturer, so heat mounting should never be used
• ILFORD made the paper and outranks a general guide, so heat mounting is fine
• They answer different questions — what the material tolerates, and what a collection should accept — so the decision is about reversibility and should be recorded with its reason
• The two statements contradict each other, so neither can be relied on and the printer should follow common practice

Show the answer and why

Answer: They answer different questions — what the material tolerates, and what a collection should accept — so the decision is about reversibility and should be recorded with its reason

Both are Tier 1 and neither is wrong; they are simply not answering the same question. ILFORD are describing what the paper survives. IPI are describing what a collection should accept, and their objection is specific: heat mounting, spray adhesives and pressure-sensitive tapes are not easily removable, so the print and the board become one object and every later decision inherits that constraint. This course therefore makes hinging the default and dry mounting a choice with its cost stated. The cost is reversibility, and the honest thing to do is write the decision and its reason on the label.

Question 8. A supplier offers a mount board described as "archival, acid-free, museum quality". What have those words established?

• That the board is buffered, lignin-free and has passed the Photographic Activity Test
• Nothing checkable: IPI state that these are marketing terms which are neither standardised nor legal, and the claim to look for instead is that the material meets ISO 18902
• That the board has a pH above 7, which is the definition of acid-free
• That the board is suitable for silver gelatin prints but not for cyanotypes

Show the answer and why

Answer: Nothing checkable: IPI state that these are marketing terms which are neither standardised nor legal, and the claim to look for instead is that the material meets ISO 18902

IPI are blunt about it: "acid-free", "archival", "museum-quality" and "conservation board" are marketing terms, neither standardised nor legal, and manufacturers sometimes have their own definitions. The printed claim worth looking for is that the material meets ISO 18902, which subsumes the Photographic Activity Test (ISO 18916) and adds the rest — pH 7.0 to 9.5, an alkaline reserve of at least 2 per cent calcium carbonate, lignin-free stock at a Kappa number of 7 or below, a colorant bleed test, no post-consumer recycled paper. IPI are equally clear that a material passing only the PAT, or only the pH requirement, is not necessarily photo-safe.

Question 9. Should a silver gelatin print be stored against buffered or unbuffered board?

• Unbuffered, because alkali weakens gelatin
• Buffered: the Library of Congress lists silver prints among the materials buffered paper may be used with, while recommending unbuffered paper for cyanotypes and architectural drawings
• Either, since the buffer is consumed within months and the distinction stops mattering
• Buffered for fibre prints and unbuffered for resin-coated ones

Show the answer and why

Answer: Buffered: the Library of Congress lists silver prints among the materials buffered paper may be used with, while recommending unbuffered paper for cyanotypes and architectural drawings

The recommendation is process-specific, which is exactly why it must not be generalised. The Library of Congress names the materials buffered paper may be used with — acetate and nitrate films, platinum prints, silver prints, chromogenic prints, and prints mounted on acidic boards — and separately recommends unbuffered paper, at pH 6 to 7, for cyanotypes and architectural drawings. So the answer for a silver gelatin print is buffered, and the answer for the Prussian blue print of Part XXI is not. Note also IPI's caution about the reserve itself: it is consumed as it reacts with acid, so its useful life is finite, and improving the storage climate does more than any enclosure can.

Question 10. Why does the course refuse to give an actionable dry-mounting procedure for resin-coated paper?

• Because the tissue makers state that their products must not be used with resin-coated paper
• Because RC paper cannot be mounted at all, and ILFORD say so
• Because the tissues' published activation band, 85 to 99 °C, sits at and above the maximum drying temperature the RC paper makers publish, and the softening mechanism they warn about is the same one — a comparison the course makes itself, since no maker answers the question directly
• Because a dry-mounting press is mains equipment and the course avoids mains equipment on Level A pages

Show the answer and why

Answer: Because the tissues' published activation band, 85 to 99 °C, sits at and above the maximum drying temperature the RC paper makers publish, and the softening mechanism they warn about is the same one — a comparison the course makes itself, since no maker answers the question directly

Neither tissue product page says anything at all about resin-coated photographic paper, which is the compatibility question a printer has. What can be put side by side is two sets of manufacturer figures: Drytac activate at 90 to 99 °C and 85 to 99 °C, while ILFORD cap hot-air drying of MULTIGRADE RC at 85 °C and Foma cap FOMASPEED at the same, and both forbid glazing because the polyethylene sticks to a hot surface. A press platen is a hot surface with pressure behind it. The course labels that comparison as its own inference rather than as a manufacturer ruling, and declines to publish a procedure on the strength of it — which is Rule 1 and Rule 7 doing their job together.

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