Part XXIII Overview: Albumen Printing

You have already made a print in which silver chloride was formed inside paper fibres and darkened by light alone. This part changes one thing about that sheet and nothing else. The chloride is dissolved in egg white before the paper ever sees it, so when the silver nitrate arrives the silver chloride forms inside a thin layer of coagulated protein sitting on the surface instead of among the cellulose. Every other difference — the depth of the blacks, the purple that gold toning reaches, the gloss, the sharpness, and the particular way these prints have aged — follows from that one relocation.

Reilly puts the general principle in one sentence in his first chapter, and it is the argument of the whole part: if the image has penetrated into the paper fibres, “the maximum density obtainable on the material will be lowered and the prints will have a matte surface, because the light reflected from the paper will be scattered and diffused by the paper fibers”; if instead it is produced “in a compact layer resting on top of the paper fibers, this scattering is minimized and the maximum density obtainable is much greater.”

One variable, and what it moves

Where the silver sits: salted paper, albumen paper, developed-out gelatin paper

Drawn to show the arrangement, not the depth: the three stacks are stacked here for comparison and are not three sections through one object. The 0.204 mm is the Getty's own measurement of a whole unmounted albumen photograph stored flat, support included. The absence of baryta under albumen is the Getty's identification test, and it is why paper fibres are visible through an albumen print's highlights and not through a gelatin one's. 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.

What the layer buys. A higher maximum density, because the reduced silver is concentrated in a thin plane instead of being spread through a scattering fibre mat. A transparent binder over the white of the paper, which Reilly says minimises the scattering in the light areas as well, so the whites look whiter and the print looks more “brilliant”. Real gloss, which is a surface property of the dried coagulated protein and has no equivalent in a salted paper. Sharpness and fine detail, because the image is not free to migrate into the fibres. And a shorter exposure scale than salted paper, which sounds like a loss and is the reason albumen suited the wet collodion negative so exactly.

What it costs. The layer is thin, brittle and dimensionally active. It swells in water, it will not tolerate a hot bath, it blisters if the temperature or the pH of a bath jumps, it cracks with age in a fine network that conservators now use to identify the process, and it yellows — so reliably that Reilly writes that “not a single albumen print survives from the 19th century without some degree of staining in non-image areas.” It also smells, it is made from a food that spoils, and it must be made a day or more ahead of the session that uses it.

And one cost that is not the layer’s fault. Albumen has no baryta — no opaque white floor of barium sulfate between the image and the paper, of the kind a fibre-base gelatin paper has had since the 1890s. That is why the paper fibres of an albumen print are still visible through its highlights under a loupe, which is the Getty’s sharpest identification test; and it is also why an acid mount board attacks these prints so directly, because, as Reilly puts it, “very little barrier exists between the silver image and the potentially destructive substances in the mount.”

What is not new here

The chemistry is Part XXII’s, unchanged. Silver chloride formed in place by double replacement, a large excess of free silver nitrate left in the layer, an image built by light alone with no development and no amplification, gold substituted for some of that silver in an alkaline bath, and a plain thiosulfate fixer. If any of that is unfamiliar, this part will read as a list of times and strengths.

Three things you learned in Part XXI are assumed and not repeated either. How an exposure scale is matched to a negative’s density range; how a hand-coated sheet is made, dried and judged; and how an ultraviolet exposure is controlled and recorded. Albumen sits at an unusual point on the first of those — Hübl measured its scale length as equal to platinum’s, with plain salted paper longer than both — so a negative made for your salt print may block up here, and that is a finding rather than a fault.

What is new is one material and everything that follows from it. That is the whole of the argument, and it is why this part has four pages rather than eight.

What this part does not repeat

Part XXII owns the chemistry. Printing out, the excess of silver nitrate over chloride and why it is needed, the practice of sensitising, gold toning, fixation in a plain thiosulfate bath and the washing sequence are all taught there, once, and cited here. This part is about the binder and about what changes because of it. If you have not read printing out and the chemistry of the salt print and gold toning and the permanence of printed-out silver, the labs here will read as a list of times and strengths with no reasons behind them.

Three things genuinely change, and they are what the pages here argue about.

What Part XXII established	What albumen changes	Where
The chloride goes on the paper in a salting solution	The chloride is dissolved in the binder, so the halide forms inside the protein	the binder lesson
A salted sheet is dry and inert until it meets silver	An albumenised sheet is water-soluble until something coagulates it, and the silver bath is doing that job as well as its own	the coating lab
Gold toner strength, times and the fixing sequence	Albumen is less permeable, so it needs a much stronger gold bath, tones more slowly, fixes with more difficulty, and never meets an acid hardening fixer	the printing lab

Reilly’s own figures make the third row concrete: toning baths for matte salted papers carry 0.1 to 0.2 g of gold chloride per litre, and toners for glossy albumen paper 0.4 to 0.5 g — four to five times as much — “because albumen is less permeable and the silver particles are more protected.”

Why it matters, in one paragraph

Albumen paper was the ordinary printing material of photography for forty years. Reilly dates the salted paper print’s dominance from 1840 to 1855 and albumen’s from 1855 to 1895; the Getty gives the main albumen period as about 1855 to about 1890 with variants surviving into the late 1920s. Reilly’s preface states the consequence that makes this part worth four pages: the albumen print “accounts for approximately 85 % of the total number of surviving 19th-century photographic prints”. Nearly every stereograph, nearly every carte de visite, nearly every studio portrait and nearly every travel view from that period is an albumen print. That is why the conservation literature on this one material is better than on anything else in Parts XXI to XXV — and it is why the deterioration lesson at the end of this part can be built out of measurements rather than out of opinion.

What is taught here and not performed

☠Ammonia fuming: the chemistry and the history, and no procedure

Fuming was a real and widespread nineteenth-century step. Reilly describes it exactly: sensitised and dried sheets were hung in a closed box and subjected to the vapours of strong ammonia standing in a dish in the bottom, usually for five to ten minutes, to make the paper more sensitive and to give richer, more brilliant prints. It was common in the United States and hardly practised at all in Europe.

The course teaches what it did and gives no method for doing it. A dish of concentrated ammonia evaporating in a closed box is a deliberate vapour generator, and the numbers are not marginal. HSE’s EH40 sets ammonia at 25 ppm (18 mg/m³) over eight hours and 35 ppm (25 mg/m³) over fifteen minutes; Chemical Safety Card 0215, quoted on the ammonia solution page, records that harmful contamination of the air can be reached very quickly on evaporation at 20 °C. Controlling that means engineered extraction, which puts the operation at Level C on the course’s rubric — a facility a home darkroom does not have, and the course’s rule is that safety overrides historical authenticity. The Level D policy sets out what “taught and not performed” means and why the course writes the chemistry and withholds the method.

Reilly’s own conclusion removes most of the sting, and it is worth having because it is a practitioner’s rather than a safety officer’s: fuming mattered most when a paper of low chloride content was sensitised on a relatively weak bath, and “much of the value of fuming may be realized by simply increasing the strength of the silver bath or by aiming for negatives of slightly different density range.” For modern practice he calls it “troublesome and unpleasant” and unnecessary. The chemistry, the history and the reasons are in the printing lab; the procedure is nowhere.

Safety framing

The part’s level, 3, is difficulty. The safety letters are assigned page by page from the classification rubric, and the two labs here sit at different letters for reasons worth understanding before you start.

⚠Three hazards, and only one of them is chemical

The coating session is Level A, and its real hazards are biological. Nothing handled there is worse than an irritant: ammonium chloride carries H302 and H319, and the isopropanol of the double-coating bath is a small quantity of a flammable liquid in a covered tray. What you are actually working with is several dozen raw eggs. 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: wash and dry hands thoroughly before and after handling eggs, clean and disinfect surfaces and equipment afterwards, do not use eggs that are cracked, damaged or dirty, and keep eggs away from other foods. The course adds one rule of its own, which is not in that document: nothing that has held photographic albumen ever goes back to preparing food, because the batch is deliberately salted, acidified and allowed to decompose, and because the next session pours silver nitrate into the same room.

The printing session is Level B, and silver nitrate sets it. The bath here is 10 to 12 per cent, stronger than the salting-and-sensitising work of Part XXII needs, and it is handled as an open tray of liquid that sheets are lifted dripping out of. Silver nitrate is classified Danger with H314, H318 and H360D among others. Splash goggles rather than spectacles, nitrile gloves, an apron, a covered bench and a spill tray, and the silver nitrate handling SOP before the bottle is opened. Every solution in that session is silver-bearing, including the first wash, and all of it is collected under the silver-bearing waste SOP.

The gold toner carries the thiocyanate rule. Where the thiocyanate toner is used it is never acidified, and no acid bath — no stop bath, no acid fixer, no vinegar — is present at that bench or in its waste bottle. Sodium thiocyanate and ammonium thiocyanate carry that rule on their own pages and the printing lab restates the control rather than the chemistry.

What you will make

Across two sessions separated by at least a day of drying, curing and ageing:

The two sessions and the waits between them

Albumen

Beat, settle 24 hStrain, then age one week in the refrigeratorUsable several weeks

Session 1 — coat

Float, dry, harden, float again, dry

Coated paper

Keeps very well, stored cool and dry — one coating session supplies several printing sessions

Session 2 — print

Sensitise, dry, expose, wash, tone, fix, wash, dry, mount — all inside 24 to 48 h

The spans show order and relative duration, not a scale in days. The week of ageing is Reilly's; the 24-to-48-hour life of sensitised paper is his too, and it is the reason the second session cannot be split across two evenings.

Coated albumen paper, salted in the binder, floated, dried and cured, in a quantity that will supply more than one printing session — because coated but unsensitised paper “will keep very well if stored in a cool and dry place”, and that fact is what makes the two-session structure workable rather than merely inconvenient.

A gold-toned albumen print from your standard negative, printed by inspection, toned by inspection, fixed in two fresh baths and washed properly, with the whole record written down.

The third row of the process comparison atlas — measured exposure scale, maximum density, image colour, surface, cost and difficulty for this process as you ran it, on the same negative as your cyanotype and your salt print. Part XXV’s assignment closes that table, and it is only worth anything if every row was measured by the same person in the same room.

And one thing you will make almost by accident, which is worth more than any of them: an untoned control print. The printing lab asks you to fix and dry one print with no toning at all. It is Reilly’s own recommendation for beginners, because without it you have no baseline for what the gold did. Keep it with its toned twin, dated, in the same enclosure. Every claim on the deterioration page about the value of toning rests on mechanism, on 170 years of practitioner consensus, and on comparative observation of surviving objects — and not on a controlled trial, because nobody read for this course has published one. That pair of prints is the beginning of one.

What changes from the last time you floated a sheet

Three things, and each of them is the reason a page in this part exists.

The chloride moves house. In Part XXII you floated paper on a chloride solution and the salt ended up in the fibres. Here it is dissolved in the binder before the paper is touched, so the silver chloride forms in the protein. That single relocation is the whole part.

The sensitiser acquires a third job. On plain salted paper the silver bath makes the halide and leaves the excess. Here it also has to coagulate the binder, because an albumenised sheet is water-soluble until something makes it otherwise, and Reilly’s account of why an albumen coating survives processing is precisely that “contact with silver nitrate in the sensitizing bath coagulates it”. The consequence is counter-intuitive and it governs the printing session: a stronger bath coagulates the layer faster, so it permeates more slowly, so it needs a longer float — while a weaker bath permeates readily and may dissolve the layer before it has set. The float time stops being a guideline and becomes a limit.

And every bath afterwards has a ceiling on it that a salt print did not have. Albumen is less permeable than paper fibre, so the gold toner runs four to five times stronger and still works more slowly. It blisters if temperature or pH jumps between trays, so everything is held near 21 °C and the fixer is deliberately made slightly alkaline. And it is thin, brittle and glued to a sheet that moves with the humidity, so the print curls, must be mounted, and must never be dry mounted.

Cost

The band is ££ for the part as a whole and £££ for the printing lab, and the split is brutal: the binder is nearly free and the sensitiser is not.

A litre of albumen is about thirty-five large eggs, because Reilly gives roughly one ounce of white per large egg, and the ammonium chloride and acetic acid that go into it are a few grams and a few millilitres. A litre of a 12 per cent silver bath is 120 g of silver nitrate, and the two dated UK listings in src/data/prices.json work out at £2.40 and £11.29 per gram, so the same litre is somewhere between about £290 and about £1,350 of capital sitting in a tray. It is not consumed in one session — the bath is replenished by the volume the sheets carry away, and Reilly’s own worked example loses 150 mL from a litre in a printing session — but it has to be bought before the first sheet is floated, and it is the reason a reader may sensibly do this part with a bought kit rather than from the raw salt. Both routes are costed on the printing lab.

!What the price file cannot tell you yet

src/data/prices.json prices silver nitrate, nitrile gloves, splash goggles, dishes, tongs, sodium carbonate, sodium sulfite and, since the survey of 7 September 2026, sodium thiosulfate pentahydrate as a raw salt — so it can now price rather more of a session here than it could. It still holds no dated UK listing for eggs, for ammonium chloride, for gold chloride, for isopropanol, for glacial acetic acid, or for the thin smooth rag paper this process wants. It names every one of them as a gap, several on this part’s own account, and a named gap is a recorded absence rather than a figure. Every consumables table in this part therefore still reports a floor rather than a total, and says which rows have no number and why.

The pages of this part

Four pages, and the order is the reasoning: what the material is, how it is made and put on paper, how it is turned into a picture, and what happens to that picture over a century.

Page	What it settles	Level
Egg albumen as a photographic binder	What egg white is, what beating and ageing and coagulation do to it, why the chloride goes into the binder, and where the density, the colour and the gloss come from	—
Lab: preparing and coating albumen paper	Separating, salting, whipping, settling, straining, ageing, floating, drying, curing and double coating, with the record that makes a batch repeatable	A
Lab: sensitising, printing and toning an albumen print	The float that must not dissolve the layer, printing by inspection, the albumen-specific limits on every bath, and a finished mounted print	B
The albumen print as an object, and how it decays	What the finished object is, why almost every surviving example is yellowed and cracked, how much of that is settled chemistry, and what a maker today should do differently	—

Behind them sits a formulary that is already written: the albumen solution with its chloride and its acid, the diluted albumenised salting solution that is the same formula with water in it, the double-coating procedure with its alcohol bath, the albumen sensitiser, the two gold toners (borax, thiocyanate), Reilly’s alkaline fixing bath with the carbonate addition that exists specifically to stop albumen blistering, and an encyclopaedia entry for albumen itself. No quantity is repeated in the lesson pages. A lesson says why a formulation has the shape it has and sends you to the formulary for what to weigh.

What you need first

The whole of Part XXII. Not as background — as the chemistry this part is a variation on. The printing lab here assumes you have already sensitised a sheet, printed one out by inspection, judged a gold toner and fixed and washed a printed-out image.

Gelatin, the photographic binder and coating, drying and hardening from Part V. Albumen is the other protein, and almost everything interesting about it is a contrast with gelatin: it is coagulated by metal salts where gelatin is not, it is coagulated by alcohol where gelatin swells, it is used partly decomposed where gelatin is bought pure and graded, and it holds silver in a way gelatin does not.

Negatives and papers for the alternative processes from Part XXI, for the standard negative and for the vocabulary of exposure scale against density range. Albumen wants a shorter density range than plain salted paper and a much longer one than an enlarging paper, and that page is where the comparison lives.

Part XVI’s ultraviolet chain and the contact printing frame with a split back, because a printing-out process is judged by opening half the frame and looking.

Alternative route

No darkroom. The coating session does not need one: an albumenised sheet is not light-sensitive until it meets silver nitrate, and Bostick & Sullivan say so plainly in their own kit instructions. It can be done in a lit room on a covered table. What the printing session needs is not a darkroom in the Part XVI sense but subdued light — Bostick & Sullivan specify a red safelight, a red compact fluorescent bulb or red LEDs, and add that the red lights “can be very bright and will not interfere in the processing”. Reilly’s requirement is the same and slightly stricter: white light excluded from sensitising and all subsequent handling, with a brief look under a low-wattage white incandescent lamp to judge exposure and toning, because yellow light hides the separation of the middle and shadow tones. A room with the window blocked and a red lamp meets that; a bathroom at night meets it. What has no substitute is a sink with running water, because the first wash and the final wash are both long and both need changes of water.

No ultraviolet unit. Sunlight is the historical source and remains a good one: Reilly gives an average exposure for albumen paper in direct sunlight as 5 to 10 minutes, and in shade anywhere from half an hour to several days. Two limitations are his and are worth knowing before you plan an outdoor session. Sensitivity is “considerably lowered when the temperature dips below 5 °C”, so printing outdoors in winter is impractical; and a cold frame put out into sunlight can expand unevenly and give a doubled image around the edges of a large print. Use the outdoor exposure session SOP and the exposure log and record the conditions instead of a dose.

No source of eggs you want to break by the dozen, or no tolerance for the smell. There is a real substitute and it is in the sources. 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; and Bostick & Sullivan’s kit is built on exactly that — their pre-mixed albumen is “a ready-to-use salted albumen solution made from food grade powdered egg whites” with a preservative in it, and they give it a shelf life of three months unrefrigerated or twenty-four to thirty-six months refrigerated, against the several weeks Reilly gives a fresh batch. That route removes the separating, the whipping, the settling, the straining and the week of ageing, and with them most of what the coating lab is about. It is the honest alternative for a reader who cannot do the preparation, and that page runs the two side by side rather than pretending they are the same.

No way to run the wet work at all. Then this part is a reading part, and it is a good one. The binder lesson and the deterioration lesson are chemistry, history and conservation evidence from end to end and need nothing but the page. The formulary entries carry the mechanism at greater depth than the lessons do. And the deterioration lesson’s assignment — comparing the conservation description of a period albumen print with a real one — can be done in any collection that will let you look at a carte de visite under a loupe.

Part23 of 28Level3 — AdvancedPages4Estimated time7.6 hoursHighest safety levelLevel B

✱1 of 4 pages in this part need a darkroom, a UV source or mains-powered equipment, marked below. Each says what can be improvised and, where one exists, gives an alternative route.

0 / 4 lessons in this part completed

• LessonEgg Albumen: A Protein Binder and What It Does to Silver50 min
• LabLab: Preparing and Coating Albumen PaperA180 min
• LabLab: Sensitising, Printing and Toning an Albumen PrintB✱ Darkroom · UV180 min
• LessonThe Albumen Print as an Object, and How It Decays45 min