Lab: Preparing and Coating Albumen Paper

Purpose

To make the material. By the end of this session you will have a batch of salted albumen resting in a refrigerator and, a week later, a stack of coated sheets that are flat, even, glossy and completely insensitive to light — because nothing here is light-sensitive until silver nitrate arrives in the next session.

The session is deliberately split by a wait. You cannot coat with albumen you beat this morning: it has to settle for twenty-four hours and then age for a week, and Reilly’s end point for that ageing is a description rather than a clock — “a yellowish homogeneous liquid with a slight ‘aged’ odour that signals its readiness for use.” Plan the two halves of this page a week apart and the whole part becomes easy; plan them on the same afternoon and nothing will work.

Learning objectives

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

• Separate egg whites cleanly enough for photographic use, and say what each of yolk, blood and chalaza would do to a coating.
• State why the chloride and the acid go into the white before the beating and not after, and what each of the three is for.
• Beat, settle, strain and age a batch of albumen, and judge from its appearance and smell whether it is ready, usable, or finished.
• Float a sheet of paper on albumen without trapping air under it, draw it off without a flood of runoff, and hang and blot it so that it dries evenly.
• Harden a first coat and float a second onto it without dissolving the first, and explain why 70 per cent alcohol and not neat alcohol.
• Inspect a dry coated sheet in raking light and decide, with a reason, whether to keep it.
• Keep a record complete enough that a difference between two prints made a month apart can be traced to something you did.

Prerequisites

Egg albumen as a photographic binder, which is where the reasons for every step below live. This page gives the operations; that page gives the protein.

Negatives and papers for the alternative processes from Part XXI, for how a paper is chosen for a hand-coated process and what sizing does.

Coating, drying and hardening from Part V, for the general craft of getting an even layer onto a support and for the vocabulary of coating weight and drying. Floating is not a technique that page teaches, and this one does.

Weighing a solid and recording a batch, because the albumen you make today is a batch with a number and the printing session in a fortnight will refer to it.

Safety classification

Level A, on the course rubric, and the criteria that apply are the Level A ones about substances and quantities: no substance handled here is classified beyond irritant or harmful if swallowed at the concentrations used, no solution is heated above 50 °C in the wet work, nothing is built or plugged in, and the waste is dilute organic rinse water plus a small volume of used alcohol.

Two things raise a step above that baseline, and both are named here rather than left inside the procedure.

A declared Level B step: none. Nothing in this session meets a Level B criterion. That is worth stating plainly, because the next page is Level B and it is easy to carry its precautions backwards into this one and then get sloppy about the ones that actually matter here.

A raised control that is not a chemical one. Several dozen raw eggs are broken on a bench. The Food Standards Agency’s catering guidance states that “no egg can be guaranteed to be free from Salmonella, whatever the source or brand”, and gives the controls used below. That is a food-safety document and this is not a food operation, so it is cited for what it does establish — hand washing, cleaning and disinfecting surfaces and equipment afterwards, rejecting cracked, damaged or dirty eggs, and keeping eggs away from other foods — and not for anything about photographic use, which it does not address at all.

⚠What is not a hazard here, and why

The albumen is not a hazard, and the course says so on the evidence rather than by assumption. Its encyclopaedia page records the search: PubChem holds no compound record for albumen, egg white or ovalbumin as materials, the ILO-WHO safety card index holds no card, the FDA registry entry carries identifiers and no GHS classification, and HSE’s EH40 lists neither albumen nor egg white — while stating in its own introduction that absence from the list does not indicate that a substance is without risk. That is an absence of classification, not a finding of safety. What the course controls here is microbiological and it is stated above.

The coated sheet is not light-sensitive. Bostick & Sullivan say it outright for their own kit — “the albumen coated paper is not light sensitive before this step”, the step being sensitising — and Blanquart-Evrard’s original 1850 account said the same: the dried albumenised paper “was not light sensitive and would keep indefinitely in the albumenized condition”. So this whole session runs in ordinary room light with the window open, and no safelight discipline applies. That is not true of anything else in this part.

There is no vapour to control in the first half of the session. Egg white does not evaporate into anything, and the 2 mL of glacial acetic acid goes into 30 mL of water inside a fume-free minute. The second half is different and Ventilation says how.

And what the same substances are like when they are not in this configuration. Ammonium chloride in a hot solution, or as an airborne dust from a large weighing, is a respiratory irritant and NIOSH’s personal-protection entry for the fume asks for eyewash and quick-drench provision; here it is fifteen grams dissolved in thirty millilitres of water in a covered vessel. Isopropanol in a large open tray in an unventilated room is a flammable-vapour problem; here it is a shallow tray in a ventilated space for the few minutes a batch of sheets takes to pass through it. The level belongs to the operation, not to the bottle.

Hazards

What	The hazard	The control here
Raw egg white, several dozen eggs	The FSA states that no egg can be guaranteed free from Salmonella whatever the source or brand	Hands washed and dried before and after; surfaces and equipment cleaned and disinfected afterwards; cracked, damaged or dirty eggs rejected; eggs kept away from other foods; nothing tasted; no vessel that has held photographic albumen used again for preparing food
Ammonium chloride, 15 g	Warning; H302 harmful if swallowed, H319 causes serious eye irritation	Weighed into a covered vessel over a lined bench, dissolved immediately; goggles rather than spectacles for the solid, because the serious-eye-irritation statement is carried by essentially every notifier who classifies it
Glacial acetic acid, 2 mL	Danger; H226 flammable, H314 severe skin burns and eye damage, H318 serious eye damage. The concentrate is the hazard, not the diluted result	Measured with a syringe, added to the water and never the reverse, goggles and gloves on before the bottle is opened, bottle capped and away before the albumen is touched
Isopropanol at 70 per cent, for double coating only	Danger; H225 highly flammable liquid and vapour, H319 serious eye irritation, H336 may cause drowsiness or dizziness	A shallow covered tray, no ignition source in the room, ventilation running, the tray covered between sheets and emptied into a labelled bottle at the end of the session
The batch, over days	Spoilage. A salted, acidified protein liquid is being kept deliberately warm-ish and deliberately partly decomposed	Covered vessel, refrigerated, dated label, and a low threshold for discarding — the end point is sensory and Analysis says what to look and smell for
Glass, blades, a hot iron or press	Ordinary bench hazards, and the press or iron runs above the coagulation temperature of the material you are working on	Glass handling SOP; the press is on a clear bench with the flex behind it, and nothing wet goes near it

Required PPE

Nitrile gloves throughout, and the reason is not the chemistry. Bostick & Sullivan put it exactly: “Transferring salt and oil from your hands to the paper will cause stains and anomalies to appear on your prints.” Gloves here protect the sheet from you as much as they protect you from the tray. Change them when they get albumen on them, which will be often.

Chemical splash goggles for two operations — weighing and dissolving the ammonium chloride, and measuring the glacial acetic acid — and safety spectacles for the rest. This is the distinction the classification page draws between Level A’s “eye protection” and Level B’s sealed splash goggles, and the two operations above are the only ones here where a splash into an eye is the credible failure.

A covered bench and an apron. Albumen sets hard on everything it dries on. Bostick & Sullivan warn that it “may harm painted surfaces if allowed to dry” and recommend a plastic-lined disposable cover, which is the cheapest control on this page.

And the hygiene controls are PPE here, in the sense that they are what the session actually turns on: hands washed and dried before and after handling eggs, surfaces and equipment cleaned and disinfected afterwards. Those are the FSA’s words and they are the substantive control of a Level A session whose real hazard is biological.

Ventilation

Ventilation is a control here for one substance and one only, and it is the alcohol. An openable window or an extractor running while the 70 per cent isopropanol tray is open is the requirement, with no ignition source in the room, because H225 is a vapour statement as well as a liquid one. Nothing else in the session produces a vapour: egg white does not evaporate into anything, the acetic acid is two millilitres capped inside a minute, and the ammonium chloride is a solid going into water.

The other reason to have air moving is not a hazard control at all. Coated sheets dry faster and more evenly in moving air, and a batch that dries slowly in a still, humid room will be uneven — so the window that serves the alcohol tray also serves the drying line. Where the air is very dry, the opposite problem appears at the next session; Storage says what to do about it.

Materials

Material	Quantity for the worked session	Note
Fresh hen eggs, large	About 35 for one litre of albumen	Reilly: “Only the freshest available eggs should be used, even though the albumen will be allowed to age”, and “each large egg will provide about one ounce of albumen”. Reject any that are cracked, damaged or dirty
Paper — thin, smooth, heavily sized, all-rag	10 to 12 sheets, 10 × 12 in	Reilly names Strathmore Series 500 one-ply plate finish as the closest ordinary approximation; Bostick & Sullivan use 145 to 300 gsm watercolour stock and name 310 gsm Arches Platine and Bergger COT320. The 19th-century trade used only two mills in the world, for reasons Materials cannot fix
Muslin or cheesecloth	2 pieces, about 20 × 20 cm	For straining the batch and for filtering before each coating session. Washable and reusable
Blotting paper or lint-free cloth	A few sheets	For blotting the runoff along the hanging edge, which is not optional
Archival-quality plain paper	2 sheets per sheet hardened by heat	Bostick & Sullivan sandwich the coated sheet between two clean sheets in the press
Clothes pegs or bulldog clips	4 per sheet drying	Two per sheet, on the long edge

Paper is the decision that costs the most and is hardest to reverse. The Getty’s account of what albumen printing needs from a stock is worth reading before you buy: great wet strength through the wet stages, light weight so that floating works at all, freedom from metallic impurities “responsible for the black specks that damaged processed photographs”, and freedom from chemical residues left by bleaching. That is a demanding specification, and it is why two mills supplied the entire world. Buy two or three candidates in small quantities and coat one sheet of each before committing.

Chemicals

Chemical	Quantity	Form
Albumen	1 L	Fresh egg white, separated
Ammonium chloride	15 g	Solid, dissolved in 30 mL of water with the acid
Acetic acid	2 mL	Glacial
Wetting agent	4 mL per litre of albumen, immediately before coating	See the note below on what Reilly’s figure means
Isopropyl alcohol	Enough to fill a shallow tray, at 70 per cent	Double coating only. Carries the same chloride concentration as the albumen
Ammonium chloride, again	15 g per litre of the alcohol bath	Reilly’s rule: whatever the albumen carries, the alcohol carries

Every quantity above is on the albumen solution and double-coated albumen procedure pages with its provenance, its mixing order and the function of each ingredient. Sodium chloride may be used instead of the ammonium salt, and Reilly says prints of similar colour and contrast may be expected from either or from a mixture; the cation is a spectator in the reaction that matters.

!What Reilly's surfactant figure actually says

The instruction is: “it is helpful to add a surfactant such as Kodak Photo-Flo™ 1:200 to the albumen solution. Use 4 ml of Kodak Photo-Flo™ for each liter of albumen.” Read literally, those two sentences give two different doses — 4 mL of the 1+200 working dilution is a fiftieth of the surfactant that 4 mL of the concentrate would be — and the source does not resolve it. The course does not resolve it either, because it cannot: it prints both readings, notes that the lower is a plausible dose for a spreader and the higher is not obviously wrong for a viscous protein solution, and asks you to record which you used.

What the surfactant is for is unambiguous and is Reilly’s own: it does two things, controlling bubbles, “one of the most troublesome aspects of the whole process”, and improving “the runoff characteristics of the albumen during drying”, which promotes a more even coating. Add it gently and immediately before a batch is floated, stirring “avoiding bubbles as much as possible” — which is the small joke in the middle of this procedure, since the thing you are adding to stop bubbles will make them if you stir it hard.

Equipment

• A tray slightly larger than the sheet, for the albumen. Its area sets how much albumen you need, which is the single biggest planning decision on this page.
• A second shallow tray for the alcohol bath, if you are double coating.
• A mixer or blender. Reilly’s beating is “3 minutes [in] an electric mixer or blender, or until the entire mixture has been converted to a froth”, and he notes one useful exemption: if a blender is used, it is not necessary to dissolve the chloride in water first. Whatever you use, it is thereafter dedicated to this work and does not go back to preparing food.
• Two bowls for separating — a small one to break each egg over and a larger one to pour clean whites into. Reilly’s reason is worth having: “if some contamination occurs, it is not necessary to attempt to remove a small amount of contaminant from a large amount of albumen.”
• An egg separator, which Reilly calls a convenient way to do the job.
• A covered container for the settling and the refrigerated week, labelled and dated.
• A drying line, inclined about 5 to 7 degrees so the runoff collects at one corner.
• A dry-mount press or a clothes iron, if you are hardening by heat rather than by alcohol.
• A balance, a 50 mL graduate and a syringe for the acid.
• A raking light — any bare lamp you can put at a low angle to the sheet.
• Nothing metal touches anything that will later meet silver nitrate. Reilly’s warning about metal-ferruled brushes belongs to the next session, but the habit starts here.

Estimated cost

The band is ££, and the split is unusual: the capital is a tray and a mixer, and the recurring cost is eggs and paper. The planner carries what src/data/prices.json can price. What it cannot price dominates this page, and the section below says which rows those are and why.

Estimated consumables cost

Every price with a number is the planner’s own dated UK figure and every quantity comes from the Materials and Chemicals sections above. Six of the eight rows have no number, and that is the finding rather than a blemish.

The worked session is: one litre of salted albumen made a week ahead, and ten sheets of 10 × 12 in paper coated from it, five of them double coated.

Consumed	This session	Sourced price	Cost this session
Nitrile gloves	3 pairs	£6.64 to £14.99 per box of 50 to 100	£0.40 to £0.90
Wetting agent	4 mL per litre of albumen, on the higher of the two readings of Reilly’s figure	£28.70 per 1 L of concentrate	up to £0.11
Fresh hen eggs, large	About 35, for the batch — not for the session	Not priced. src/data/prices.json holds no food listing of any kind, and this row is the whole reason it now carries a gap for one	—
Ammonium chloride	15 g in the batch, plus 15 g per litre of alcohol bath if double coating	Not priced. It is a gap the file names, and both of this part’s labs are the reason recorded against it	—
Glacial acetic acid	2 mL	Not priced. The file prices acetic acid at 80 per cent, £11.89 per litre, which is what the photographic trade sells and is a fifth weaker than the reagent this formula names; the glacial acid is a gap it names for that reason	—
Isopropyl alcohol, 70 per cent	Enough to fill a shallow tray, mostly recovered	Not priced, and named as a gap because this tray consumes it by the litre rather than by the wipe	—
Thin smooth all-rag paper, 10 × 12 in	10 sheets	Not priced. src/data/prices.json names two paper gaps and this stock is the second: thinner and smoother than the hot-press cotton watercolour paper of the first, and recorded separately for that reason	—
Muslin, blotting paper, pegs	A few of each	Not priced	—

The priced subtotal is about £0.40 to £1.00, and it is a floor rather than a total. Six of the eight consumables have no sourced price, and two of them — the eggs and the paper — are certainly the largest items. Equipment is deliberately absent from the table: a tray is not consumed, a blender is not consumed, and a dry-mount press is not consumed, so counting them would break the one thing the consumables calculator needs the table to measure.

🧮How much albumen a session needs, and why it is mostly not consumed

This is the arithmetic that decides how many eggs you break, and it has one assumption in it that is the course’s rather than a source’s.

The tray sets the volume. Reilly’s coating method is “filling a tray to a depth of approximately 2/3 to 3/4 inch with the albumen solution and floating the paper on the surface”. Two thirds to three quarters of an inch is 17 to 19 mm. For a tray whose inside floor is 21 × 26 cm — a nominal 8 × 10 dish, and that measurement is the course’s assumption and not a figure from any source —

21 cm × 26 cm × 1.7 cm = 930 mL

Volume to fill an 8 × 10 tray

so a litre is about right. Reilly recommends starting with a 10 × 12 in sheet, which needs a bigger tray again; on the same assumptions a nominal 11 × 14 dish takes about 1.7 L, which is roughly sixty eggs. Choosing the sheet size is choosing the egg bill.

What the sheets actually take away is a small fraction of it. From Reilly’s own factory figures — 9 litres of albumen to coat a ream of 480 sheets at 46 × 58 cm — the coating consumption works out at 0.70 mL per square decimetre, so a 10 × 12 in sheet (7.7 dm²) carries off about 5.4 mL single coated and 11 mL double coated. Ten sheets, five of them double coated, is about 80 mL.

Bostick & Sullivan’s yield implies four to five times that. Their litre of ready-made albumen “should make approximately 60 prints on 8x10 paper”, which is 16.7 mL per 8 × 10 sheet, or 3.2 mL per square decimetre, for a double coat. The gap between the two figures is presumably their tray losses and the albumen that cannot be poured back — the course’s guess, not their statement.

And the reason the litre is capital rather than consumption is that it goes back in the bottle. Bostick & Sullivan’s sixty-print yield only makes arithmetic sense if the bath is returned to storage and filtered again before the next session, which is exactly what their instructions tell you to do. That is an inference from a stated yield rather than a stated instruction, and it is the one that makes this process affordable: you break thirty-five eggs once and coat for weeks, until the batch goes off.

Waste streams

Stream	What is in it	Where it goes
Spent or spoiled albumen	Salted, acidified, partly decomposed egg protein. Organic load, and nothing more exotic — no silver has been near it	The dilute-organic stream. It is not silver-bearing and does not belong in the silver bottle
Rinse water from bowls, mixer and tray	Dilute albumen and chloride	The same
Used 70 per cent isopropanol	Alcohol carrying dissolved albumen, chloride and whatever came off the sheets	A labelled, capped bottle. Flammable, and it accumulates protein, so it is not kept indefinitely
Shell and separation waste	Food waste, and the FSA’s controls apply to the surfaces it touched	Ordinary food waste, and the bench cleaned and disinfected afterwards
Rejected coated sheets	Paper with dried albumen on it. Still not light-sensitive and still not silver-bearing	Ordinary paper waste — and see Analysis: keep a few as a reference of what a bad coating looks like

Nothing on this page is silver-bearing. That changes completely on the next page, where the first wash is silver-bearing waste, and the discipline of keeping the two sessions’ waste separate starts by noticing that this one has none.

Alternative route

No eggs, or no tolerance for the smell. Reilly records that “albumen may currently be obtained as a powder, of which a 15 % solution in water will approximate native egg white”, noting only that the powder is more costly and less convenient. Bostick & Sullivan’s kit is built on exactly that: their pre-mixed solution is “a ready-to-use salted albumen solution made from food grade powdered egg whites” carrying a food-grade preservative, with a shelf life of three months unrefrigerated or twenty-four to thirty-six months refrigerated. That route removes the separating, the beating, the settling, the straining and the week of ageing — which is to say, it removes about half of what this page teaches. It is the honest alternative, it produces prints, and Further experiments turns it into a controlled comparison instead of a shortcut.

Two limits on it. Neither Reilly nor Bostick & Sullivan publishes the chloride content of a reconstituted powder or of the ready-made solution, so a reader on that route cannot do the chloride arithmetic in the binder lesson and cannot vary the salting deliberately. And Bostick & Sullivan give a working temperature — the solution “works best at temperatures above 60F (14C)”, and many papers “will resist absorbing cold albumen”, so it comes out of the refrigerator at least two hours before use. Their own conversion of 60 °F is not exact, since 60 °F is 15.6 °C; the course records both figures as printed rather than correcting a source’s arithmetic silently.

No dry-mount press or iron. The heat route to hardening is Bostick & Sullivan’s. Reilly’s is the 70 per cent alcohol bath, which needs nothing but a tray, and the nineteenth-century trade’s was six months in a warm loft, which needs nothing but patience. All three are in the sources and the choice is recorded rather than assumed.

No drying line. Sheets can be laid flat on a rack, and the Getty notes that this is how flat albumen prints survive. What you lose is the deliberate gravity gradient that the double-coating reversal trick cancels — so a flat-dried sheet should be more even, and that is a claim you can test in Further experiments rather than take on trust.

No way to run this session at all. Then buy albumenised paper if you can find it, or read this page as history and go to the next one with a bought sheet. What you will not have is the variable that the whole part is about: the coating is the thing you are learning to control.

Preparation

A week before. Read the albumen solution page and decide your chloride: 1.5 per cent is Reilly’s floor and his sample preparation sits exactly on it. Buy the eggs as fresh as you can get them and keep them cool. Clear a shelf in a refrigerator and a container that will live on it.

On the day of the batch. Label the container before you start — batch number, date, chloride and its concentration, acid, egg count — through the labelling SOP and the batch record. Cover the bench. Set out the two bowls, the separator, the graduate, the syringe, the balance and the mixer, and wash and dry your hands.

A week later, on the day of coating. Bring the albumen and the paper to the temperature of the room and give them an hour to get there — Reilly’s instruction is to “condition both the paper and the albumen solution by allowing them to gradually come to the operating temperature of the work room”, and a cold solution on warm paper coats differently from a warm one. Cut the paper to size. Set up the drying line with the blotters underneath. If you are double coating, mix the alcohol bath, dissolving the chloride in the water first and adding the alcohol to it, and keep it covered until you need it.

Procedure

Part one: the batch

Six operations, and the state the albumen is in after each

1. 1SeparateClear white only. No yolk, no blood, no chalaza. Two bowls, and one bad egg costs one egg
2. 2SaltChloride and acid dissolved in a little water first, then into the whites — before the beating, not after
3. 3Whip3 minutes, or until the whole mixture is froth. Mechanical denaturation; the chalazae and membranes go up into the foam
4. 4Rest24 hours, covered. The froth liquefies and drains, and what was caught in it stays caught
5. 5DrainThe clear liquid from beneath the froth is the working albumen. The foam is discarded
6. 6FilterThrough muslin, squeezed if necessary — then a week refrigerated before it is fit to coat with

The sequence only. Every quantity is on the albumen solution's formulary page, and what each step does to the protein is on the binder lesson.

1. Wash and dry your hands. Then, and each time you come back to the eggs, again. This is the FSA’s first control and it is the one people skip.

2. Separate every egg over the small bowl and pour each clean white into the large one. Reilly’s standard is absolute: “the eggs should be separated completely and only the clear white saved — without the slightest contamination of yolk, blood or the stringy tissue known as the chalazae.” Reject any egg that is cracked, damaged or dirty before you break it. If a yolk breaks, that egg’s white goes down the sink and the small bowl is rinsed; it does not go into the batch.

3. Measure the white you have. About one ounce per large egg, so thirty-five eggs is about a litre. Work to the volume, not to the egg count.

4. Dissolve 15 g of ammonium chloride and 2 mL of glacial acetic acid in 30 mL of water, for each litre of albumen. Goggles and gloves for this step. Acid into water, never the reverse. Reilly’s own printing braces these three together with the words “combine and add to”, and the chloride goes in “dissolved in a minimum of water and added to the egg white before the beating process”. The one exemption he gives: with a blender, dissolving the chloride first is unnecessary.

5. Add the salt-and-acid solution to the whites and beat. Three minutes in an electric mixer or blender, “or until the entire mixture has been converted to a froth”. You are looking for complete conversion, not a timer.

6. Cover and let it settle for 24 hours. The froth liquefies and drains; what collects underneath is the working albumen, and the chalazae and membranes stay up in the foam.

7. Strain through muslin. Reilly notes the liquid “may have to be squeezed through the muslin with some pressure”. This is the last of the three filters — the separation, the froth, and now the cloth.

8. Cover, label, and refrigerate for one week. Then look at it and smell it before you use it: the target is a yellowish homogeneous liquid with a slight aged odour.

Part two: coating, a week later

9. Filter again, immediately before use, through muslin, and pour into the tray to a depth of two thirds to three quarters of an inch. Bostick & Sullivan’s method is a folded piece of cheesecloth loose in a funnel, which is the same idea with better ergonomics.

10. Add the surfactant and stir it in gently, avoiding bubbles. Record which reading of Reilly’s figure you used.

11. Clear the surface of bubbles. Bostick & Sullivan’s technique is the useful one: cut a strip of heavy paper about 2 × 8 in, drag it slowly through the solution pulling the bubbles to the side of the tray, run them up the side letting the excess drain back, lift it out and wipe it. Do this before every sheet, not once at the start.

12. Float the sheet. Hold two opposite corners, let the centre touch first and lower the corners away from you so no air is rolled under. Bostick & Sullivan crease the two short ends upward first, which makes a shallow tray of the sheet and keeps albumen off the back.

Floating a sheet on albumen: the three faults that happen in the tray

1. 1Lower centre-first — the corners go down last, so no air is rolled underneath. Start the clock only when the sheet lies flat and every bubble is gone
2. 2Air rolled under — light circles on a dark background through a thin sheet; invisible through a thick one, which Reilly says must be lifted and its underside inspected
3. 3Foam on the surface — swept to the side with a paper strip before every sheet, not once at the start of the session
4. 4Lifted too fast — a flood of runoff, uneven coating, and albumen round the edge onto the back. Peel one corner slowly and let it drain over the tray

Drawn from Reilly's account of floating and Bostick & Sullivan's bubble-clearing step. What each fault looks like on the dry sheet is under Analysis.

13. Check for trapped air and break it. With a thin paper the bubbles show through as light circles on a dark background; with a thicker one they do not, and Reilly’s instruction is that “each sheet must be lifted off the surface and the bottom side inspected for bubbles”. Lift by one corner, break them, lay it back down.

14. Start the clock when the sheet lies flat and every bubble is gone, and float for 1 to 1½ minutes. Timing from the moment the sheet touched the liquid is the commonest way to get an uneven batch.

15. Draw the sheet off slowly. One corner first, peeled gently. Reilly’s test of a good draw belongs to the sensitising step but applies equally here: lifted properly, hardly a drop leaves the sheet while it drains over the tray.

16. Hang it by two corners of the long edge, on a line inclined 5 to 7 degrees, with a blotter beneath the low corner.

17. Blot the runoff, several times, while it dries. This is not tidiness. Reilly: if the collected runoff is allowed to dry, “a thick rind of albumen will form and make the sheets very difficult to work with in subsequent operations. In addition, the last droplet will take a very long time to dry.”

18. Let it dry completely. Bostick & Sullivan give 60 to 90 minutes depending on temperature and humidity, and warn that the drip corner must be completely dry before anything else happens. Warm air dries faster and — Reilly’s point — glossier: factory drying rooms ran at 30 to 50 °C.

19. Pile the dry sheets and flatten them under weights. “This makes them supple and easy to handle in the further floating operations to come.”

Part three: the second coat, on half the batch

20. Harden the first coat. Choose one route and record it.

    • Alcohol (Reilly). Put the 70 per cent isopropanol, carrying the same chloride as the albumen, in a tray and “slowly pull the sheets of albumenized paper through the solution”, then hang them to dry. Reilly publishes no immersion time — he writes only of “briefly immersing the sheets” and of drawing them through — and the course does not invent one.
    • Heat (Bostick & Sullivan). Sandwich the sheet between two clean archival sheets and press for 2 minutes at 250 °F in a dry-mount press, or work a clothes iron on its highest setting slowly and evenly over the whole sheet for 2 to 3 minutes.
    • Time (the nineteenth-century trade). Six months in a warm loft. Recorded here because it is what most albumen paper was actually made with, and because it tells you the direction the other two are pushing.

21. Flatten again under weights, and mark the edge that hung lowest during the first drying.

22. Float the second coat exactly as the first, and hang the sheet with the marked edge at the top. The two gravity gradients then cancel. Bostick & Sullivan reach the same result by draining from diagonally opposite corners on the two coats.

23. Dry, and harden the second coat too if you are following Bostick & Sullivan. Reilly does not, and the reason is on the binder lesson: for a single top coat, the silver bath does the coagulating. Whichever you choose, write it down — it is one of the variables the next session will blame if the layer dissolves.

Part four: inspection

24. Look at every sheet in raking light before it goes in the box, and decide. The next section says what you are looking for.

Expected observations

During the beating. The froth builds fast and then stops building. Reilly’s note that the chloride “reduce[s] the volume of froth produced during the beating step” is visible if you have ever beaten an unsalted white: this one makes less foam and makes it more grudgingly. That is the salt denaturing the protein, and it is a sign the chloride went in at the right time.

During the settling. A clear-ish liquid collects beneath a shrinking cap of foam, and stringy material stays up in the foam. If you tilt the container you can see how much thicker the top layer is than what is underneath.

After the week. Yellowish, homogeneous, pourable, with a slight aged smell. Reilly’s word is “slight”. A batch that announces itself across the room has gone further than his method intends.

During floating. The paper relaxes and lies flat within a few seconds; Bostick & Sullivan describe it “almost immediately relax[ing] and lay[ing] flat on the Albumen”. Bubbles rise to the edges if the surfactant is doing its job.

During drying. The sheet cockles and curls, and Bostick & Sullivan say so explicitly: “the paper will reticulate and become partly curled while the Albumen is drying. This is normal, and should not affect the paper or final image adversely.” Do not fight it; the weights fix it afterwards.

On the dry sheet. A faint sheen that is not the paper’s own, strongest where the coating is thickest. Reilly’s description of dried albumen is “a brittle, transparent mass”, and a corner of a badly over-coated sheet will confirm the “brittle” if you flex it.

On a double-coated sheet. More sheen, more curl, and a stiffer feel. Reilly’s warning is that two coatings can leave papers “so heavily coated that they are brittle and hard to tone.”

What is happening chemically

The chloride is doing three jobs at once, and only one of them is photographic. It will make silver chloride next session; it helps denature the protein now, which Reilly names as one of the three denaturing treatments; and it visibly reduces the froth volume, which is the same denaturation seen from the outside.

The acid is doing one job, and it is a structural one. Reilly’s sentence is the mechanism: “the chemical forces which bind together the enormous molecules of protein grow weaker as the pH is lowered, and the physical properties of the substance change as a result.” Native egg white sits at pH 7.8; glossy albumen papers are made with partly decomposed, acid albumen, “because in that condition it creates a glossier surface and more even coating, and has less tendency to yellow after sensitization.” Fresh alkaline albumen is used only for matte papers, and then always mixed with starch or another substance — which is the whole difference between this page and matte albumen.

The beating is mechanical denaturation. Egg white is not one substance but several proteins with different viscosities — ovalbumin alone is 54 per cent of the protein, and there are at least six others — and beating them to a froth and letting them fall back produces, in Reilly’s words, “a homogeneous liquid which will form an even layer on the sheet of paper.”

The week is chemical denaturation continuing slowly. What the sources establish is that decomposition drives the albumen acid and homogeneous, and that aged or fermented albumen coats more evenly and glossier. What no source read for this course establishes is what the organisms are, what they make, or how much of the effect is simply the falling pH. The binder lesson marks that as contested and this page does not pretend otherwise.

And the coating itself is not yet a chemical event at all. The dried layer is denatured protein, not coagulated protein: it is still soluble in water, and it stays soluble until something coagulates it. That is why the hardening step exists between two coats, and it is why the next session’s float is a race rather than a soak.

🔬What the film is doing as it dries

Water leaves, the protein chains are forced together, and the greasy patches that beating exposed find each other. The layer that results is transparent — Reilly’s “brittle, transparent mass” — and it follows the surface of the paper it dried on, which is why a smooth heavily sized sheet gives gloss and a rough one does not.

Two properties of that film are worth carrying to the next page. It is thin: the Getty measured a whole unmounted albumen photograph, support included, at 0.204 mm, and publishes no separate figure for the layer. And it is dimensionally active: it takes up water and gives it back with the humidity of the room, while the paper beneath it does the same at a different rate. That mismatch is what curls the sheet on the drying line tonight and what cracks the layer in a century.

Data to record

Use the lab notebook worksheet and the batch record. The list below is what the next two sessions will ask you for, which is the only test of a record that matters.

The batch. Batch number and date. Egg source, count and grade. Volume of albumen obtained, and the implied millilitres per egg. Chloride, which salt, mass, and the resulting per cent w/v against the albumen volume. Acid and volume. Beating method and duration, and whether the mixture was wholly frothed. Settling time. Straining medium. Date into the refrigerator and date first used. Appearance and smell on the day of first use, in your own words.

The coating. Room temperature and, if you can measure it, relative humidity. Albumen temperature. Surfactant, which product, which reading of the dose, and how much. Tray size and depth of solution. Sheet size and paper, by name and basis weight. Float time. Whether bubbles were found and how many. Drying: hanging or flat, temperature, and elapsed time to dry. Number of blottings.

The second coat. Hardening route, and its parameters — alcohol strength and chloride, or press temperature and time, or elapsed weeks. Whether the sheet was reversed for the second float. Float time again.

The inspection. For every sheet: a number written in pencil on the back near the edge, a verdict of keep or reject, and the reason. Count the rejects; the reject rate is the number that tells you whether your technique improved between batch two and batch three.

And the mass balance, if you will do one thing beyond the list. Weigh the albumen in the tray before and after the session, and divide the loss by the total area you coated. That single figure — millilitres per square decimetre on your bench — turns the arithmetic in Estimated consumables cost from an argument into a measurement, and it is the number the whole part would most like to have.

Analysis

Reading a sheet in raking light

Put a bare lamp low and to one side and look across the sheet rather than at it. Four faults show up this way and nothing else shows them at all.

A coated sheet under raking light: four faults and where each comes from

1. 1A fine, evenly spread field of small circles — foam sitting on the surface of the bath when the sheet went down. Prevented by dragging a paper strip across the surface before every sheet, and by adding the surfactant gently
2. 2A few large isolated circles with hard edges — air trapped underneath. Prevented by lowering the sheet centre-first, and cured by lifting a corner and breaking them before the clock starts
3. 3Vertical streaks in the direction of drainage — runoff channelling as the sheet dried. Blotting the low corner repeatedly is the fix; a surfactant improves the runoff characteristics, which is half of what Reilly says it is for
4. 4A hard ridge along the bottom edge — the rind. Runoff allowed to dry in place. It makes the sheet difficult to handle in every later operation
5. 5A gradient thin-to-thick from top to bottom — gravity, and it is expected. Reilly: the severity varies but it is "usually not so pronounced as to render a batch of paper completely unsuitable". Cancel it on the second coat, do not chase it on the first

Drawn from the causes the sources name. The distinction between fault 1 and fault 2 — an even field against a few isolated circles — is the course's own reading of Reilly's account of trapped air and Bostick & Sullivan's account of surface bubbles, and it is offered as a diagnostic rather than as a quotation.

The decision rule. Reject a sheet if a fault falls where the image will be and cannot be trimmed out. Keep it if the fault is in the margin — Reilly’s reason for starting at 10 × 12 in is precisely that it “leaves plenty of margin area when one 8 x 10 or four 4 x 5 prints are desired”, and a margin is exactly where a bubble is harmless. Keep the worst rejects. A drawer of known faults is worth more than a page of descriptions when the next batch goes wrong.

Judging the batch

Ready: yellowish, homogeneous, pours cleanly, slight aged odour.

Finished: Reilly’s criterion is sensory and it is the only one in the sources — “the smell of the albumen and its color, sedimentation, etc., will reveal when it has decomposed too badly to use.” So: a strong smell rather than a slight one, a colour that has gone further than yellowish, or sediment that does not disperse when you swirl it.

!What the sources do not tell you about spoilage

No document read for this part gives a time at room temperature after which a fresh salted albumen batch must be discarded, gives a microbiological criterion, or reports what grows in one. What Reilly gives is a shelf life under refrigeration — usable for several weeks after the one-week ageing period — and a sensory end point.

The only numerical shelf life in the corpus belongs to a different material: Bostick & Sullivan’s solution is made from powdered egg white and carries “a food-grade preservative to help extend its life”, and their three months unrefrigerated and twenty-four to thirty-six months refrigerated are figures for that product. Applying them to a fresh batch with no preservative in it would be inventing a shelf life, and the course will not.

So the rule this page gives is a conservative one and it is the course’s own: keep it cold, keep it covered, keep it dated, use it within a few weeks, and throw away anything you are unsure about. Thirty-five eggs is cheaper than a session’s work and very much cheaper than a spoiled print.

Troubleshooting

What you see	Likely cause	What to do
A fine, evenly spread field of small pale circles over much of the sheet	Foam on the surface of the bath when the sheet went down	Clear the surface with a paper strip before every sheet. Add the surfactant gently and let the bath stand a few minutes before the first sheet
A few large isolated pale circles with hard edges	Air trapped under the sheet	Lower the sheet centre-first. Lift a corner and break them before the clock starts. On thick paper, lift the sheet and inspect the underside — Reilly says you must
Streaks running in the drainage direction	Runoff channelling during drying	Blot the low corner repeatedly. Check the surfactant, whose second stated purpose is exactly to improve the runoff characteristics
A hard ridge along one edge that makes the sheet unmanageable	The rind: runoff dried in place	There is no cure once dry. Prevent it by blotting several times during drying
The second coat gives no extra gloss or thickness	The first coat dissolved off during the second float	The first coat was not hardened, or the hardening was insufficient. The tray is now contaminated with dissolved albumen: filter it or discard it
Neat alcohol used for the hardening bath, and the layer looks blotchy	Reilly: “pure alcohol is too strong and unevenly coagulates the albumen layer”	Remake the bath at 70 per cent, and put the same chloride into it that the albumen carries
The sheets seem less salted than they should, after alcohol hardening	The chloride leached out of the layer into an alcohol bath that carried none	Reilly’s rule, and it is easy to skip: “if the albumen contains 2 % ammonium chloride, so should the alcohol solution”
The coating looks grey, greasy or unevenly matte in patches	Yolk contamination	It cannot be fixed and it cannot be filtered out. Discard the batch and separate more carefully — this is why Reilly separates over a small bowl
The paper will not take the albumen and the liquid beads on it	The albumen is cold, or the paper is	Both must be at room temperature. Bostick & Sullivan note that “many papers will resist absorbing cold albumen” and take theirs out of the refrigerator two hours before use
Small hard flecks in the dried coating	Undissolved chloride, or unstrained material	Dissolve the chloride fully in its water before it meets the whites, and filter through muslin both after settling and again before coating
Black specks in the finished print, traced back to the paper	Metallic impurities in the stock	The Getty names this as one of the two things a photographic rawstock had to be free of. It is a paper problem, not a coating problem; change the paper

Clean-up

Everything gets washed the same day. Dried albumen is difficult to remove and Bostick & Sullivan note that it “may harm painted surfaces if allowed to dry”. Cold water first — hot water coagulates the residue onto the vessel and makes it worse, which is the same 65 °C fact from the other end.

Then clean and disinfect the surfaces and equipment, in the FSA’s words, because that is the control that closes the biological loop. Wash and dry your hands afterwards.

Return the albumen to its bottle through the muslin if you intend to use it again, and put it back in the refrigerator. Record the date and what came out of it, because a filtered-back bath is not the same bath it was this morning.

The alcohol goes into a labelled bottle, capped, away from ignition sources. It now carries dissolved albumen and chloride and it is not indefinitely reusable.

And put the tray away marked. A tray that has held photographic albumen is a photographic tray from now on. Bostick & Sullivan label theirs and say the same thing more bluntly: “Do not cross-contaminate!”

Storage

The batch lives covered, dated and refrigerated, and is judged by appearance and smell before every use.

The coated sheets keep well, and this is the fact that makes the two-session structure work. Reilly: “Once the sheets have been albumenized, they will keep very well if stored in a cool and dry place.” Blanquart-Evrard’s original account went further and said the albumenised paper “would keep indefinitely in the albumenized condition”, though that is a claim from 1850 and no source read for this course tests it. No document read for this part publishes a measured keeping time for coated but unsensitised albumen paper, so the course states what the sources state — that it keeps very well, cool and dry — and does not put a number on it.

Flat, and interleaved. Pile the sheets and keep them under weights. If they must be rolled, Reilly’s instruction is specific and is about the brittleness of the layer: “it is better to roll them with the albumen side out so that the cracking of the albumen is minimized.” A layer rolled inwards is in compression and buckles; rolled outwards it is in tension and survives.

And do not let them dry out completely. This is the one storage instruction that looks like a contradiction and is not. Reilly’s rule for the next session is that sheets “must not be excessively dry at the time of sensitization, because if too dry, they will not properly absorb the silver nitrate solution”, and his remedy is to put them overnight somewhere damp, “such as a basement”, which also makes them more supple and easier to handle. So the sheets are stored dry, and conditioned damp the night before they are used. Read that instruction on the next page before you plan your fortnight.

Disposal considerations

The albumen streams are organic load and nothing more exotic. Dilute albumen in rinse water is oxygen-demanding organic matter; a spoiled batch is the same thing more concentrated. Neither carries a heavy metal, because no silver has been in this room. The general chemistry is that a protein solution is biodegradable and that its impact on a treatment works is a loading question rather than a toxicity one.

The alcohol is different in kind. It is a flammable organic liquid carrying dissolved protein and chloride, it accumulates over sessions, and it is bottled and labelled rather than run away. Follow the general chemical waste procedure.

The shell and separation waste is food waste, and the surfaces it touched are cleaned and disinfected.

Local regulation governs all of it, and the course cannot tell you what yours says. What it can tell you is the chemistry, which is above, and the general practice, which is to keep the streams separate, label what is in each and how old it is, and ask before you assume. See the disposal ruling. Check your local regulations.

Questions

1. Reilly says the chloride “should be dissolved in a minimum of water and added to the egg white before the beating process”, and then adds that with a blender it need not be dissolved first. What is the risk the first instruction manages, and why does a blender remove it?

2. You have two batches: one salted at 1.5 per cent ammonium chloride and one at 1.0 per cent. From Reilly’s figures, which will be more sensitive, which will give more contrast from a thin negative, and which will give the richer, denser image? Which would you choose for a first attempt, and why?

3. A reader argues that since the albumen is going to be allowed to decompose anyway, the eggs need not be fresh. Answer them using Reilly’s own instruction and one sentence of reasoning about what fresh and stale mean for a protein.

4. Explain to somebody who has coated silver gelatin emulsions why an albumen sheet cannot simply be immersed in the bath, and why it is coated on one side only.

5. Your alcohol hardening bath carries no chloride and your albumen carries 1.5 per cent. Trace what happens over a batch of ten sheets pulled through the same tray, and say what you would see in the finished prints.

6. The gravity gradient thins the top of a hanging sheet and thickens the bottom. Reilly’s answer is to reverse the sheet for the second float. What is the equivalent answer for a single-coated sheet, and what does Reilly say about whether it needs one?

7. You are asked how much albumen a coating session “uses”. Give two defensible answers with their units, and say which one belongs in a consumables table and why.

Further experiments

Fresh against aged, properly controlled. Split a single beaten and settled batch in two on the day it is strained. Coat five sheets from half of it within twenty-four hours — which is what Reilly’s matte albumen method does, using albumen “at most 24 hours after it has settled back to a liquid state” — and refrigerate the other half for the week, then coat five more. Hold constant: the eggs, the chloride and its concentration, the acid, the beating, the paper and its batch, the surfactant and its dose, the tray and depth, the float time, the room temperature and humidity, the drying arrangement and the number of coats. Vary: the age of the albumen, and nothing else. Judge the ten sheets in raking light for evenness and streaking before any of them is sensitised, then carry two of each into the printing session and compare gloss and maximum density on the finished prints. Reilly and the Getty both predict the aged half will coat more evenly and print glossier; this is how you find out whether that is true on your bench.

Single against double, measured rather than asserted. Carry the two halves of this session’s batch through to finished prints from the same negative, and measure maximum density with the densitometer of Part XV. Record the toning time each needed, because Reilly predicts the double-coated sheet will tone more slowly and less evenly, and that prediction is easier to test than the density one.

Hanging against flat drying. Dry half a batch on the line and half flat on a rack. Compare the gradient top to bottom, the streaking, and the gloss. Reilly’s claim is about the gradient; the gloss comparison is not in any source read for this course and would be a genuine finding either way.

Chloride series. Three batches at 1.0, 1.5 and 2.5 per cent, everything else held. Reilly predicts the low one is less sensitive and slightly more contrasty from a thin negative at the cost of density, and that above 1.5 you are mostly buying silver consumption. Two of those are testable in a printing session; the third is testable with a balance and a receipt.

The two hardening routes, head to head. Alcohol against heat, on sheets from the same batch and the same coating session, judged by whether the second coat added thickness and by whether the layer survived sensitising. This is the comparison the sources do not make — Reilly gives alcohol and Bostick & Sullivan give heat, and nobody read for this course has run them side by side.

The mass balance, repeated. Weigh the bath before and after three consecutive sessions and plot millilitres per square decimetre against session number. If your technique is improving, the figure should fall and then flatten.

Check your understanding

Question 1. Your dried sheets show a fine, evenly spread pattern of small pale circles over most of the coated area. What caused it, and which step prevents it?

• Air trapped under the sheet; prevented by lowering the sheet centre-first
• Foam sitting on the surface of the bath; prevented by dragging a paper strip across the surface before every sheet
• Dust on the paper; prevented by brushing the sheet before floating
• Undissolved chloride; prevented by dissolving the salt in water before it meets the whites

Show the answer and why

Answer: Foam sitting on the surface of the bath; prevented by dragging a paper strip across the surface before every sheet

The distinguishing feature is that the circles are small, many and evenly spread. Air trapped underneath gives a few large isolated circles with hard edges, and Reilly describes those as visible through a thin sheet as light circles on a dark background. A whole field of small ones is the bath's own foam, which Bostick & Sullivan clear with a paper spatula before each sheet — and which is why Reilly's surfactant is added for bubble control as well as for runoff.

Question 2. Why must the alcohol used to harden a first coat of albumen carry the same chloride concentration as the albumen itself?

• Because the chloride is what coagulates the albumen, and the alcohol only carries it
• Because otherwise the chloride leaches out of the layer into the bath, silently reducing the salting of the paper
• Because pure alcohol would dissolve the layer rather than coagulate it
• Because the chloride prevents the alcohol from evaporating too fast

Show the answer and why

Answer: Because otherwise the chloride leaches out of the layer into the bath, silently reducing the salting of the paper

Reilly gives the rule and the reason together: "To prevent leaching out of the chlorides from the albumen, whatever chloride content is present in the albumen itself should also be added to the alcohol solution." The coagulation is done by the alcohol, at 70 per cent — pure alcohol coagulates unevenly and too dilute a solution lets the layer dissolve before it sets. Lose the chloride and you have quietly moved down Reilly's salting scale without changing your formula, which is the hardest kind of error to trace.

Question 3. Which of these are established by the sources cited on this page? Select all that apply.

• Coated but unsensitised albumen paper keeps very well in a cool, dry place
• A fresh salted albumen batch must be discarded after 48 hours at room temperature
• Albumen paper is not light-sensitive until it has been treated with silver nitrate
• A large egg yields about one ounce of albumen

Show the answer and why

Answer: Coated but unsensitised albumen paper keeps very well in a cool, dry place, Albumen paper is not light-sensitive until it has been treated with silver nitrate, A large egg yields about one ounce of albumen

The second is invented, and this page says so explicitly: no document read for this part gives a room-temperature spoilage time for a fresh batch, a microbiological criterion, or an account of what grows in one. What exists is Reilly's sensory end point and his several-weeks refrigerated life — and a numerical shelf life belonging to a different material, Bostick & Sullivan's preserved solution made from powdered egg white. Do not carry one product's shelf life onto another's.

Question 4. Design a fair test of fresh albumen against week-aged albumen. Which of these must be held constant for the comparison to mean anything?

• The eggs, the chloride concentration, the acid and the beating
• The paper, its batch, the float time, the tray depth and the number of coats
• The room temperature, the humidity and the drying arrangement
• The negative used to print the finished sheets

Show the answer and why

Answer: The eggs, the chloride concentration, the acid and the beating, The paper, its batch, the float time, the tray depth and the number of coats, The room temperature, the humidity and the drying arrangement, The negative used to print the finished sheets

All of them, which is the point of the question. The only way to hold the eggs and the beating constant is to split one batch after straining rather than to make two batches — otherwise the comparison contains the egg-to-egg and beating-to-beating variation as well as the ageing, and you cannot tell which produced the difference. Humidity is the one most often forgotten and it changes both the drying rate and the final coating; record it even if you cannot control it.

Question 5. A reader plans to prepare the albumen in the morning, strain it at lunchtime and coat in the afternoon. What will go wrong, and what does Reilly's own matte albumen method suggest about how wrong?

• Nothing: the settling and ageing are conveniences rather than requirements
• The albumen will not have settled, so the chalazae and membranes go onto the paper; and it will not have aged, so it coats less evenly and prints less glossy
• The coating will not be light-sensitive without the week of ageing
• The chloride will not have dissolved fully in the time available

Show the answer and why

Answer: The albumen will not have settled, so the chalazae and membranes go onto the paper; and it will not have aged, so it coats less evenly and prints less glossy

Two separate failures. The 24-hour settling is what lets the froth carry the chalazae and membrane fragments out of the liquid, and skipping it puts them on the sheet. The week is the ageing, and Reilly and the Getty both attribute even coating and higher gloss to partly decomposed albumen. Reilly's matte albumen method is the useful qualifier: it deliberately uses albumen "at most 24 hours after it has settled back to a liquid state" — so unaged albumen is a real, published material, it is simply the wrong material for a glossy print.

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