Assignment: The Hand-Coated Print

The intention

Everything in this part has been a measurement. This is the one piece of work in it that has to be looked at rather than read, and the standard it is held to is not whether the coating is even. It is whether the picture is better on the paper you made than on the paper you can buy — and if it is not, whether you can say precisely what it cost and what it bought.

You will make one finished print, or one lantern slide, on an emulsion you made yourself; in three variants, of which you select one; presented beside the same image on commercial paper; with a record complete enough that somebody else could make the same sheet again.

Learning objectives

By the end of the assignment you should be able to:

• choose an emulsion for an image and defend the choice on the material’s properties rather than on which batch you have most of;
• design a three-variant set that changes one thing at a time, and select from it on stated criteria;
• read a hand-coated print against a machine-coated one and name what the surface adds and what it costs;
• write a print record that ties a finished object back through a coating weight and a version code to a melt and a formula;
• complete the five-emulsion comparison matrix and say what it shows that no single batch record could.

Prerequisites

At least one of Projects 1, 2, 3 or 5 completed and coated, with its batch record. If you took the accessibility route and worked on a bought liquid emulsion throughout, do the assignment on that: it is the same assignment with one of its variables removed, and the page says which one.

The break/fix page matters here more than it looks, because half of this assignment is deciding which faults you are going to accept.

Safety classification

Level A. No silver nitrate is weighed or handled: the emulsions were made in earlier sessions and what happens here is coating, printing and processing. The baths are the same working-strength paper developer, dilute stop and fixer used throughout the course.

What is not a hazard here, and why. There is no new substance on the bench. Silver halide sitting in a dry gelatin layer is not the reagent that made it — silver nitrate is corrosive and an oxidiser, and a coated sheet is neither — and the quantities in the baths are the same ones every processing session in this course has used. What remains is ordinary wet-darkroom discipline: one pair of tongs per tray, never swapped, gloves and eye protection, and a floor that stays dry.

Hazards

Used fixer and first wash are silver-bearing, as in every session, and are collected.

Working under a safelight for two hours. The hazard is trips and spills rather than chemistry. Lay the bench out in the light, and know where the towel is.

A tender wet layer. If your emulsion is unhardened — which is this course’s default — it is physically fragile while wet, and a print destroyed by a squeegee at the last step is the commonest way this assignment goes wrong.

Required PPE

Nitrile gloves, eye protection, apron and closed shoes, as every processing session in this course. The gloves have a second job here: they keep fingerprints off a print you intend to keep.

Ventilation

Ordinary room ventilation. None of the three baths at working strength generates a vapour that would call for extraction, and no powder is weighed in this session, so the still-air rule that governs the project pages does not apply.

Materials

Your coated sheets, at least six of them; a negative or a photogram subject; commercial paper of a comparable size for the side-by-side; the step wedge; a pencil; and the trays and tongs you have been using. If you are presenting a lantern slide instead, add a light box or a window and a black card mask.

Chemicals

This assignment introduces no chemical you have not already used, and there is nothing to weigh. What is present, and stays present, is the working-strength paper developer, the dilute stop and the fixer from the processing sequence Project 1 established, plus — if your emulsion frills — an acid hardening fixer carrying potassium alum, which is the one substitution this page might ask you to make.

The silver is in your sheets, as silver chloride, silver bromide or both, held in gelatin.

Equipment

The station, the trays, the safelight, the fixed lamp and its measured distance, and a glass-and-board sandwich under a weight for the contact print — this part has no printing frame, which Part XVI builds.

Estimated cost

Cost band £. Everything material was bought for the projects. What this session consumes is six sheets and an evening. This page quotes no prices; dated figures live in the laboratory planner.

Waste streams

Used fixer and first wash, silver-bearing and collected, as in every processing session.

Failed prints divide into two cases the course keeps apart, because they are not the same waste. A sheet that was fixed and washed carries developed metallic silver only, and the silver is bound in the gelatin rather than free to leach. A sheet that failed before or during fixing still carries unreduced silver halide, and that one belongs in the silver-bearing solid waste without exception. Neither goes into ordinary paper recycling.

Where those streams may then go is not a question this course can answer for your address. See the disposal caveat, which is maintained centrally and which every waste section in the course cites rather than restating: the classification is national, the route is local, and the authority that decides is the one whose area you are in.

Alternative route

The assignment is a print, a set of variants and a record that makes the choice between them defensible. Three of those four things survive every substitution below.

No emulsion of your own. Coat the three variants in bought liquid emulsion. The five-emulsion matrix then becomes a five-coating matrix — weight, method, substrate, drying and hardening — and every column in it still has to be filled from your own batch record. The commercial-emulsion route is where that starts, and the submission is graded the same way.

No darkroom. Nothing here needs an enlarger: the print is a contact print under glass and a weight. What it does need is a space that can be made dark to coat and to expose, and a windowless room at night with a red LED is the usual answer. See Part V’s overview for why this is the one requirement of the part with no substitute.

No 21-step transmission wedge. Print your own step ladder on the commercial paper, as the commissioning session does, and use it as a relative scale. It will not give you absolute densities and it does not need to: the comparison here is between three of your own coatings and one bought sheet, and a relative ladder ranks them perfectly well. Say in the record which instrument you used.

No negative you want to print. A photogram is accepted. The chemistry, the coating and the critique are unchanged, and a leaf against a hand-coated sheet is a harder test of even coating than a negative is, because there is nothing in the image to hide behind.

What cannot be substituted is the record: the version code, the coating weight, the batch notes and the reasoned selection of one variant out of three. Without those the submission is a print rather than an assignment.

Preparation

1. Choosing the emulsion for the image

Not “which do I have most of”. The four materials behave differently and the differences are the ones you measured.

Emulsion	What it is like, on the evidence	Choose it for
Chloride, Project 1	Slow, contrasty, very fine-grained. Wall describes the image of a chloride emulsion as more like a stain than the normal silver image, and warm tones as easy to reach on it	A short-scale subject; a warm image; small prints where the fineness shows
Chlorobromide, Project 2	A chloride paper with a bromide addition. A little faster, a slightly longer scale, still easy to work warm	A subject with more range than the chloride can hold
Bromide, Project 3	Much the fastest, longest scale, coldest in a normal developer	A negative with a long range; anything needing a short exposure
Orthochromatic, Project 5	The bromide, plus green sensitivity	Only if the picture uses it — a photogram of coloured objects, or a negative you want to render differently
Commercial liquid emulsion	Somebody else’s material on your surface	The accessibility route, and the honest control against your own makes

!One thing the emulsion does not choose, and it is the one everyone expects it to

Image colour is not set by the halide. Wall made emulsions across the whole range from pure chloride to pure bromide, developed every one of them in a single metol-hydroquinone developer, and got the same coloured image every time. His conclusion is the rate at which silver is deposited, not the composition of the emulsion — and Chapman Jones supplied the mechanism from the other side, showing that the colour depends on the size of the silver particles, which slow deposition makes fine.

So if you want a warm print, the lever is the developer: dilution, temperature, time, and added bromide. What the halide ratio decides is how easily the warm end is reachable at a usable exposure, because a chloride-rich emulsion develops slowly and a slow development is what makes warmth available. Choose the emulsion for its speed and its scale, and reach for the colour with the developer.

2. Choosing the surface and the edge

The surface is a decision and not a leftover. Paper texture changes what the image can hold: a hot-pressed sheet keeps fine detail, a rougher one breaks the image into its own grain. Sheet size changes how the coat reads, because a coating fault that is invisible at postcard size dominates at half-plate.

The edge is the most visible thing you will decide. A rod-coated sheet gives a rectangle with a slightly ragged border where the bead started and stopped; a brush gives a deliberate soft edge; a masked coat gives a clean rectangle with a hard boundary. All three are legitimate and none of them is the default — but a brush edge on a picture that does not want one reads as decoration, and it is worth asking whether the edge is doing work.

The lantern slide is an alternative object, not a lesser one. A positive on glass is looked through rather than at, and it is the only object in this part that a room full of people can see at once.

3. Choosing the negative

Four routes, and the constraint is the same for all of them: this part has no enlarger, so the negative must be the size of the print.

• A photogram — objects laid on the sheet. No negative needed, immediate, and it suits an orthochromatic emulsion because coloured objects render differently from the way they look.
• The student’s own film negative, if it is large enough to contact print.
• A paper negative, made in the Part VI camera on a sheet you coated and reserved.
• A digital negative, printed on transparent film. The course’s method for these belongs to the alternative-process cluster — Part XXI’s page on the negatives, papers and light these processes need — and this page does not invent a second one. Use the method that part specifies when you reach it, or use one of the other three routes now.

The assignment, in the order it has to happen

1. 1Choose, and write the choice downemulsion, surface, edge, negative, and one sentence on why each — before any sheet is exposed
2. 2Find the exposure on a test stripthe step wedge already tells you roughly where; a strip refines it for this negative
3. 3Make three variantsone variable moved across the three: exposure, or developer condition, or surface
4. 4Print the same image on commercial papersame negative, same evening, matched as closely as you can; this is the control
5. 5Select one, and record whystated criteria, written before you look at them together if you can manage it
6. 6Write the record and complete the matrixversion code, coating weight, batch notes, the step wedge, and the five-emulsion matrix

The order matters at two points. The choices are written before any exposure, so that the assignment is a plan carried out rather than a result explained afterwards; and the commercial print is made on the same evening from the same negative, because a control made a week later controls nothing.

The making

The three variants

Three sheets, from the same batch, differing in one thing. Pick the axis before you start.

• Exposure. The simplest, and the one that teaches least. Use it if the emulsion is new to you.
• Developer condition. Working strength, diluted, and diluted with extra bromide. This is the axis Wall’s series says actually moves image colour, so it is the one that will show you something you could not have predicted.
• Surface. The same emulsion at the same coating weight on three papers, or three coating weights on one paper. If you choose coating weight, compute all three: it moves maximum density and speed together, and knowing by how much is worth more than the print.

Whatever you choose, hold everything else, and write down what “everything else” was. A variant set that differs in two things is three prints rather than an experiment.

The commercial control

Print the same negative on bought paper, the same evening, matched as closely as you can for the shadow end. It is not a competition and the bought paper will usually win on evenness. That is not the question. The question is what the two objects do differently, and you cannot answer it from memory a week later.

What to lay out, and what to look at when you do

1. 1The three variants — one variable across the row, its value labelled under each print
2. 2The selected print — chosen on stated criteria, not on which looks nicest at a glance
3. 3The commercial control — same negative, same evening; compare maximum black, highlight, surface and edge
4. 4The step wedge — from the same batch, threshold and maximum-black steps marked
5. 5The two records — batch record and print record: version code, coating weight, and every processing figure

Drawn as a layout rather than measured. Everything in the bottom row exists so that somebody who was not there can tell whether the top row means anything.

Expected observations

• The hand-coated print’s maximum black is probably not as deep as the commercial paper’s, and the first suspect is coating weight rather than the emulsion. Baker’s warning applies exactly here.
• The highlights are different in kind, not just in value. A commercial paper carries a baryta layer — barium sulfate in gelatin — between its base and its emulsion, as the coating lesson sets out, and yours has not; so your paper white is the paper’s own white showing through the layer.
• The surface reflects differently as you tilt it, and it is the property a scan will not carry.
• A fault you would have rejected on a test sheet may be one you keep. That decision is the assignment, and it has to be stated rather than made silently.

The record to keep

Three documents, and together they are the portfolio entry the capstone will reuse.

1. The batch record

Already written, from the project. It carries the version code, the formula and its source, every quantity, the temperatures and times, the coating weight, and the faults you found. This assignment adds one line: which sheets from that batch became this print.

2. The print record

Field	Example
Print title, date	Window, 4 a.m. — 2026-09-20
Emulsion version code and batch	KCl-01a, coated sheet 3 of 4
Coating weight, computed	about 100 mg/dm²
Paper brand, weight and lot	90 lb hot press, lot on the wrapper
Negative: kind, size, source	paper negative, 4 × 5, Part VI camera
Lamp, distance, exposure for each variant	40 W at 900 mm; 18 s / 25 s / 35 s
Developer, dilution, temperature, time	working strength, 20 °C, 2.5 min
Stop, fix, wash	dilute stop 1 min; two-bath fix 3 + 3; wash 20 min
Step wedge from this batch: threshold step, maximum-black step, scale in steps	4, 16, 12 steps
Which variant was selected, and on what criterion	variant 2, for shadow separation
Faults present, and accepted or rejected	one stroke line at the top edge — accepted
What was changed from the previous print, and why	half a stop less, because variant 3 blocked the shadows

On the schemas this record has to fit. The course’s laboratory-notebook conventions are owned by Part XXVII and the exposure log by Part VI, and neither is written to its final form yet. This page does not invent a third schema: the fields above are the batch record’s, extended by what a print needs, and reconciling them with those two parts is a task those parts own. If your fields differ, record more rather than less.

3. The five-emulsion comparison matrix

Completed, from Project 5. It is the single document in this part that shows a progression rather than a result, and the last two rows are the ones worth arguing with when it is full: image colour, which Wall’s series says is the developer’s business rather than the emulsion’s, and scale, where the two Tier 1 sources this course holds give opposite directions for what bromide does to contrast and your row is your own evidence.

📓What makes a record evidence rather than a diary

Three properties, and the third is the one people leave out.

Traceability. Every number on the print record leads back through the version code to a melt, a formula and a source. A print you cannot trace is a picture; a print you can trace is a measurement.

The negative result. Record the variants you rejected and why, not only the one you kept. The rejected sheets are half the information and they cost the same to make.

The change you did not make. A paper lot whose sizing recipe was changed by its manufacturer is documented as causing blistering during processing, and a different lot as producing mottled fading late in the wash — faults that took weeks and half a dozen batches to diagnose because nothing on the bench had changed. Write down the brand and the lot. A change you did not make is still a change, and without the lot number it is invisible.

The critique

Two hundred words, written after the prints are dry and laid out, answering six things in order. Write it for somebody who was not there.

Tone. Where does the print sit overall, and is that where you meant it to sit? Name the deepest black and the lightest tone that still holds detail.

Contrast. Does the scale of the print match the scale of the subject, or did you fit one to the other? Say which, because fitting the subject to a contrasty material is a legitimate decision and an accident is not.

Surface. What does the hand-coated surface do that the commercial sheet does not — and what does it cost? Both halves. If the answer is only that it costs evenness, look again at the highlights.

Edge. Is the edge doing work, or is it there because that is how the emulsion stopped?

Defects: accepted or rejected. List the faults you can see, name each one from the break/fix page, and say for each whether you kept it and why. “It is part of the process” is not a reason. “The stroke line runs with the window frame and I decided it belonged” is.

Intention. One sentence on what the picture is for, and one on whether the material served it. If the honest answer is that the commercial paper served it better, say so — that is a finding, and it is worth more to your next print than a defended one would be.

Troubleshooting

What you see	Likely cause	What to do
Weak maximum black on every variant	Too thin a coat, before the emulsion	Compute the coating weight; coat one sheet at twice it and reprint variant 2
The emulsion lifts or frills during development	Adhesion, and possibly this developer specifically	Fix in an acid hardening fixer, or change developer. Do not add a hardener to the emulsion at this stage
Thick areas darken days after the print was finished	Incomplete fixing of a thick, possibly hardened patch	Refix and rewash promptly. Next time fix for twice the clearing time in a two-bath sequence
All three variants look identical	The variable did not move far enough	Widen the interval. On the developer axis, dilute further and extend the time rather than changing product
The print is warmer or colder than you wanted	The developer, not the emulsion	Change dilution, temperature or added bromide, and hold the emulsion constant
The commercial control is not comparable	It was printed to a different shadow value, or on a different day	Reprint both, matched at the shadow end, in one session

Clean-up

The processing trays and tongs as every session; the emulsion pot and coating tools washed in warm water before the gelatin sets. Failed prints go into the silver-bearing solid waste, not into paper recycling. Wash gloves before removing them.

Storage

Dry the print flat, face up, on a clean surface or a screen, out of dust. If your emulsion is unhardened the wet layer is tender: handle by the corners the whole time it is wet, never squeegee it, pull it from the last wash and hang or lay it by a corner. Once dry it is no longer tender.

Store it interleaved with clean paper, flat, out of warm damp storage, with the version code and date pencilled on the back. The course’s presentation, flattening and mounting conventions belong to Part XIX, and this page defers to them rather than inventing an alternative.

What nobody has established: the keeping behaviour of a hand-coated fibre print made from these emulsions. Baker’s industrial keeping test — ten days at 41 °C below 65 per cent relative humidity, with no more than 0.02 extra fog against controls — is a figure for a coated plate in a factory. Nothing this course has read gives one for a print you made. Date it, keep one rejected variant in the same box, and look at both in a year.

What to submit

Laid out as the drawing above shows:

1. The three variants, labelled with the value the variable took on each.
2. The selected print, and the commercial control of the same image beside it.
3. The step-wedge strip from the same batch, with the threshold and maximum-black steps marked. On a 21-step wedge each step is 0.15 density, which the maker gives as half a stop.
4. The batch record and the print record.
5. The five-emulsion comparison matrix, completed.
6. The critique, two hundred words.

Further work

The same negative on all four emulsions. One image, four materials, matched coating weights, one developer. It is the most direct answer this part can give to the question of what a halide ratio actually looks like, and nobody in this course’s corpus has published the comparison.

The developer axis, taken seriously. Print one negative on one emulsion in four developer conditions and set the four side by side. Wall’s finding predicts that the colour will move with the deposition rate and not with anything else you have done; a hundred-year-old result, and yours to confirm or refute on your own materials.

The keeping test you can actually run. Two identical prints from the same batch: one in a box, one taped where daylight reaches it. Look at both in six months. Permanence is Part XII’s subject, and this is the cheapest possible first data point in it.