Assignment: Your Archival Processing Sequence

Everything in Parts VIII to XII was an argument about one step. This is where the steps become a sequence, and the sequence becomes a document somebody else could follow — including you, in five years, having forgotten why you chose 1+4 rather than 1+9.

What you are producing

One standard operating procedure, in the form the SOP library uses, covering film from developer to dry and fibre-base print from developer to dry. Two executions of it, one film and one print. Three pieces of evidence that it worked. One revision, with a version number and a note of what changed and why. And one paragraph stating how permanent you need this print to be and what you gave up to get there.

That is a capstone gate rather than an exercise. The test it has to pass is not “is it correct”; it is could a stranger execute it, and could you reconstruct from it, years later, exactly what you did. A procedure that only works because you remember something is not a procedure.

Part 1 — What an SOP is, and what it is not

Read two of the ten procedures in the library before you write a line — routing silver-bearing waste and closing the laboratory are the two that will teach you the most about the form — and notice what they never do.

A lesson explains. An SOP is followed, in a hurry, with wet hands. Everything follows from that.

The seven sections, and what each one is for

1. 1PurposeOne or two sentences: what this procedure achieves. Not why the chemistry works — a link does that.
2. 2When to use itThe trigger. "Every film session" is a trigger; "when processing film" is a restatement of the title.
3. 3Before you startWhat must already be true and what must already be on the bench. This is where the reading, the mixing and the labelling live, so that the Procedure can be pure action.
4. 4ProcedureImperative, numbered consecutively from 1, one action per step. No mechanism. Where a step depends on one, it links the lesson that owns it and moves on.
5. 5How you know it workedObservable outcomes, not intentions. "The clearing time was under two minutes" is one; "fixed properly" is not.
6. 6If a step failsKeyed to the step number. This is what separates a procedure from a recipe, and it is not optional.
7. 7What to recordThe line that goes in the notebook and the log. If nothing is recorded, nothing can be revised.

The order is fixed and the build checks it on the library's own pages. Yours is not checked by a script, which is exactly why you should follow it.

Three rules do most of the work.

Numbered, imperative, one action per step. “Fix for twice the clearing time, agitating for the first 30 seconds and at 30-second intervals” is a step. “Fixing is important and should be done carefully” is not a step; it is an opinion with a full stop.

Never explain a mechanism. If you find yourself writing a paragraph about why thiosulfate dissolves silver bromide, cut it and link how fixer works instead. The habit is hard to break and it is the single commonest way a first SOP goes wrong: it becomes a lesson with numbers down the side, and then it is too long to use.

“If a step fails” is written before you need it. Every step that can fail gets an entry keyed to its number, saying what to do. A procedure that only describes the successful path is a recipe, and a recipe is what you were following before this assignment.

Part 2 — Drafting the sequence

Every step in your procedure carries the same seven fields, and a step missing one of them is a step you have not actually decided.

Field	Why it is not optional
Solution and dilution	Written as 1+4, never 1:4 — Part II’s dilution convention is not pedantry, since ILFORD and Kodak use the two notations differently.
Volume	Because a dilution is not a quantity, and minimum-volume rules bite at small tank sizes.
Temperature, with a tolerance	A number without a tolerance is a wish. ILFORD’s optimum-permanence sequence specifies 18 to 24 °C including the wash water, which is the part people miss.
Time, and how it was arrived at	“Twice the clearing time measured today” is a rule; “5 minutes” is a number that will be wrong when the bath ages.
Agitation	Kodak’s own film sequence specifies continuous for the first 30 seconds and then at 30-second intervals; if yours differs, that is a decision and it belongs in writing.
Capacity limit, and where it is logged	The step is not finished until it says when the solution is retired and where that count lives.
Waste route	Which container. Not “dispose of appropriately”.

Two published sequences are your reference points, not your answer. Kodak’s own instruction for black-and-white film runs develop, stop, fix for twice the clearing time, rinse 30 seconds, hypo clearing agent 1 to 2 minutes, wash 5 minutes — or, in a small tank, fill to overflowing and dump ten times — then a wetting agent for 30 seconds and dry. ILFORD’s optimum-permanence sequence for fibre paper is fixation at 1+4 for one minute, a five-minute first wash, ten minutes in a washing aid at 1+4, and a five-minute final wash, with the instruction not to add a hardener to the fixer and to be careful neither to exceed the fixer’s capacity nor to extend the fixing time, because both make washing harder.

Your job is not to transcribe either. It is to decide, for your materials, your water and your sink, and to say which parts you took, which you changed and on what grounds. Where you diverge from a manufacturer, the SOP says so in one line.

✕Four places a first draft usually breaks

The wash step has no criterion. “Wash for 30 minutes” is a duration, not an outcome. Add what you will observe or test, and what you do if it fails.

Fixing time is fixed. If it is a number rather than “twice today’s clearing time”, the procedure is silently assuming the bath never ages. It does, and Part XI’s criterion is the rule that replaces the number.

Hardener is in the fixer without a decision behind it. F-5 is a hardening fixer and there are pages of this course where hardening is what you want. This is not one of them: ILFORD’s optimum-permanence instruction is explicit, and the physics of washing explains what a hardened emulsion does to the wash. Choose, and write down that you chose.

The waste line says “dispose of appropriately”. Name the container. Every step that produces a liquid ends in one, and the silver-bearing waste procedure already distinguishes the first wash from the later ones.

Part 3 — Justifying every step

For each step, one line: what it does, and the page that owns why. Not a paragraph — a link. The SOP itself carries only the link; the justification list is a separate sheet that stays with the draft and is what you hand in.

Your step	The part that owns it
Developer choice, dilution, time, temperature	Part VIII for the mechanism, Part IX for how you measured your own figure
Agitation scheme	Part VIII on kinetics
Stop bath, or a water rinse instead	Part X, which is also where the choice not to use one is argued
Fixer type, dilution, one bath or two	Part XI
Fixing time and the retirement rule	Part XI’s criterion
The rinse between fix and washing aid	Part XII on washing
Washing aid, or none	The same page, which owns the ion-exchange argument
Wash schedule and water use	The same page
Whether to tone	Permanence and image deterioration, which names it and hands the practice to Part XX
Drying and storage	The same page
Every waste route	The disposal caveat and the two waste procedures

The test this list applies. A step you cannot justify is one of two things, and both are worth finding: a habit you inherited from somebody who had a reason you do not share, or a mistake. Neither survives being written down next to an empty cell.

Part 4 — Executing it

One film and one fibre-base print, processed strictly by the draft, with a second person’s eye if you can get one — because the point of the execution is to find the steps that are unfollowable, and the author is the worst possible judge of that.

Carry an unexposed white sheet of the same paper through the print’s whole sequence. Kodak’s 1949 instruction is exactly this: process with the batch a sheet of the same weight and size as the prints, and cut a strip from it after the final wash. It must be unexposed because a test needs somewhere with no image silver to read a stain against.

Measure on the day, not from memory: the clearing time of the film in the bath you are actually using, every solution’s temperature including the wash, and the running totals in the capacity log. Note anything you did that the draft does not say to do. That is not cheating; it is the most valuable data the session produces, and it goes straight into Part 6.

Part 5 — The evidence

Three results, and each answers a different question.

One: the clearing time, and twice it. From the drop-on-a-scrap method. This says the bath was fit and that the film was fixed long enough. It says nothing about the print and nothing about washing.

Two: a residual thiosulfate test on the control sheet. This says the wash worked.

Three: a residual silver test on a white area of the print. This says the fixing worked — a different failure, with a different cause and a different remedy.

!HT-2 and ST-1, and what this course actually asks you to run

The classical designations for tests two and three are Kodak’s HT-2 and ST-1, and you will meet both names in every discussion of archival processing.

Both are now published, as HT-2 and ST-1, and that is a correction to what this page said on 5 September 2026. The only Kodak publication in the corpus that carries them is a scan with no extractable text, and a text search of the whole corpus found neither designation. On 6 September the scan was read as page images instead, and its printed page 41 gives both formulas with their reading procedures. The earlier statement was true about a search and wrong about the document, which is a distinction worth keeping in mind every time this course says a thing cannot be sourced.

One of them you have been running all along. ILFORD’s residual-silver test — 2 g of sodium sulfide in 125 mL, diluted 1+9, one drop on a white area of a washed print, blotted and read against a reference spot on a print known to be well fixed — is the composition Kodak publishes as ST-1. Two makers, one test, and the course reached it through the one whose sheet it could read.

HT-2 is not the test this part runs, and the difference is not cosmetic. HT-2 is 7.5 g of silver nitrate per litre acidified with 125 mL of 28 per cent acetic acid, applied as a drop for two minutes and read against the printed tints of the KODAK Hypo Estimator. What the Part XII lab runs is Kodak Limited’s 1949 hypo test: a plain 1 per cent silver nitrate immersion of the control strip for about three minutes, read wet against the untreated part of the same sheet. Different reagent, different application, different reading — and the formulary page says what HT-2 would cost you, because without the Estimator card, which this course does not hold and cannot reproduce, HT-2 gives you a stain and no scale.

Say in your submission which you ran. That rule has not changed and is the whole point of the paragraphs above. “HT-2” against a test that was not HT-2 is precisely the kind of borrowed authority a record re-read in ten years cannot check — and it is now possible to run HT-2 and name it correctly.

📓What the three results may and may not be called

Every one of these is the course’s own measurement under the course’s own stated criterion, and that phrase is not modesty. The limits that would let anyone certify a print as permanent live in international standards this course names by number and does not hold, quote or restate; Part XI states the criterion it uses instead, in full, where you can check it.

Two more boundaries belong in the record. ILFORD’s sulfide test needs a well washed print and is not effective on one straight from the fixer, so a failure on an unwashed print tells you nothing. And a bath-side instrument is not a substitute for a test on the material: Kodak states that on-site methods “cannot typically be used to demonstrate regulatory compliance”, and the same logic applies here — a reading of the fixer tells you about the fixer.

Part 6 — Revising, and giving the revision a number

Now put the draft beside what you actually did, and change it.

1. Every departure you noted becomes either a corrected step or a deliberate exception. If you did it differently and the result was fine, the procedure was wrong. If you did it differently and the result was worse, the procedure was right and the note explains why.
2. Every step that failed gets an entry under “If a step fails”, keyed to its number, whether or not it failed for you.
3. Change one thing at a time in any future revision. Part IX’s rule applies to procedures as well as to experiments: two changes at once means the next result cannot be attributed to either.
4. Number it. v1.0 for the draft, v1.1 for this revision, and a dated line saying what changed and why. A filled notebook page from v1.0 stays a valid record of what v1.0 asked for — and that is only true if the number moves. The course’s own printable worksheets carry their version on every sheet for the same reason.
5. Set a review date. The library’s procedures carry one, a year out. Yours should too, because your water changes, your paper is discontinued and your sink moves house.

Part 7 — Art track: how permanent does this print need to be?

This is the part the science and craft tracks cannot answer for you, and it has a cost attached, which is what makes it a real decision rather than a preference.

ILFORD publishes two ceilings, not one. For “a high level of image permanence” in commercial use, keep the silver in the fixer below 2 g/L — about forty 8 × 10 fibre prints per litre. For prints needing “maximum stability for long term storage”, below 0.5 g/L — about ten prints per litre. The standard fixing and washing recommendations, ILFORD says plainly, already “give excellent print permanence for all commercial needs”.

📷What the higher standard actually costs

Four times the fixer, four times the bottles, and four times the silver-bearing waste for the same number of prints — the arithmetic is on the silver recovery page, where a printer holding to the maximum-stability ceiling makes twenty-four litres of spent fixer a year against six at the commercial one. It also costs a longer sequence, more water, and a wash that has to be tested rather than assumed.

None of that is an argument against it. It is an argument for deciding, and for saying which you decided. A work print made to see whether a composition holds does not need the archival sequence, and running one on it is not virtue, it is twenty-three litres of waste and an afternoon.

Write the paragraph. Name the print, say what you expect of it — a wall for a decade, a portfolio handled weekly, a negative that outlives you — and say which ceiling you held to and what you accepted in exchange. If you decided that this particular print does not need the archival sequence, say that too, and say what would change your mind. Both are defensible; only the unstated one is not.

Alternative route

This assignment needs a darkroom because it ends in a fixed, washed and dried print, and there is no version of an archival processing sequence that never wets paper.

What it does not need is a room. Everything here works in a bathroom commissioned for the evening by the method Part II gives, and the wash stage — which is most of the elapsed time and all of the water — is not light-sensitive at all: once the print is fixed it can be carried out and washed in daylight, which is how most fibre printing has always been done.

If you have no darkroom yet and do not want to wait, run the film half of the sequence alone. A daylight tank needs darkness only for loading, which a changing bag supplies, and film carries the residual-thiosulfate test just as paper does. The print half then joins later, and the SOP you write is amended rather than started again — which is itself the lesson, because a processing standard that cannot absorb a change of facilities was written too tightly.

What to submit

• The SOP, at v1.1, in the seven sections, with the film and fibre-print sequences either as one document with two Procedure branches or as two documents — your choice, stated and justified.
• The justification sheet: every step, one line, one link.
• The execution record: the notebook pages for both sessions, with measured temperatures, the clearing time, the capacity-log lines and every departure noted.
• The three test results, with the reagent and procedure named — the ones you actually ran — the reference each stain was read against, and what each result does and does not certify.
• The revision note: what changed between v1.0 and v1.1, and why.
• The permanence paragraph.
• The waste lines for the session: which containers took what, and the date you last checked your local route.

Recap

A procedure is not a recipe: it is imperative, numbered, mechanism-free, and it says what to do when a step fails. Every step carries a solution, a dilution, a volume, a temperature with a tolerance, a time and how it was derived, an agitation scheme, a capacity limit, and a waste route — and a step missing one of those is a decision you have not made. Kodak’s and ILFORD’s published sequences are the reference points you diverge from on the record, not the answer you copy. The evidence is a clearing time, a residual-thiosulfate test and a residual-silver test, run with the procedures this course can actually publish and named as such, and every result is the course’s own measurement under its own stated criterion rather than a certification. Then it gets revised, numbered and dated — because the only version of this document that matters is the one a stranger, or a much older you, can still act on.

Check your understanding

Question 1. A draft SOP contains this step: "7. Fix the film for 5 minutes in Ilford Rapid Fixer at 1+4, since thiosulfate needs time to convert the insoluble first silver complex into the soluble second one." What are the two separate faults?

• The dilution is wrong and the time is too short
• It fixes for a fixed time rather than twice the clearing time measured on the day, and it explains a mechanism instead of linking the page that owns it
• It names a proprietary product, and 1+4 should be written 1:4
• It has no temperature, and no agitation scheme

Show the answer and why

Answer: It fixes for a fixed time rather than twice the clearing time measured on the day, and it explains a mechanism instead of linking the page that owns it

The first fault is substantive: a fixed time silently assumes the bath never ages, and Part XI's criterion — fix for twice the clearing time measured today, retire the bath when that time exceeds twice its fresh figure — is the rule that replaces the number. The second is a fault of form and it is the commonest one in a first draft: the clause about the two complexes is true, is Kodak's 1924 explanation, and belongs on a lesson page that this step should link. An SOP is read in a hurry with wet hands, and every sentence of chemistry in it is a sentence somebody has to skip. The fourth option names two real omissions, but the step as quoted has larger problems than either.

Question 2. You submit an SOP whose evidence section reads "HT-2: negative. ST-1: negative." You ran the Part XII lab exactly as it is written. Why is that record still unacceptable?

• Because HT-2 and ST-1 are obsolete and have been superseded
• Because the lab runs Kodak Limited's 1 per cent silver nitrate immersion, which is not HT-2, so half the record names a test that was not performed
• Because a negative result is not evidence, only a positive one is
• Because the tests must be run on film as well as on paper

Show the answer and why

Answer: Because the lab runs Kodak Limited's 1 per cent silver nitrate immersion, which is not HT-2, so half the record names a test that was not performed

The point is traceability rather than correctness. The ST-1 half of that record is defensible: ILFORD's sodium sulphide test at 2 g in 125 ml diluted 1+9 is the composition Kodak publishes as ST-1, so a print tested that way was tested with ST-1's reagent under another maker's name. The HT-2 half is not. HT-2 is 7.5 g of silver nitrate per litre acidified with 28 per cent acetic acid, read as a two-minute drop against the printed tints of the Hypo Estimator; the lab runs a plain 1 per cent silver nitrate immersion for about three minutes, read wet against the untreated part of the same sheet. Both formulas are in the formulary and you may run either — but the record has to name the one you actually mixed, or a reader in ten years cannot tell what reagent made the stain.

Question 3. A printer works to ILFORD’s maximum-stability ceiling of 0.5 g of silver per litre of fixer instead of the 2 g/L commercial one. Making 240 fibre prints of 8 × 10 in a year, roughly how does the spent-fixer volume compare?

• The same, because the same number of prints carries the same silver
• About 24 L instead of about 6 L, because the ceilings correspond to about ten and about forty prints per litre
• About 12 L instead of about 6 L, since the ceiling is halved
• About 6 L instead of about 24 L — the tighter ceiling means less fixer, not more

Show the answer and why

Answer: About 24 L instead of about 6 L, because the ceilings correspond to about ten and about forty prints per litre

ILFORD states both ceilings with their print counts: below 2 g/L is approximately forty 8 × 10 fibre prints per litre, below 0.5 g/L approximately ten. So 240 prints need 240 ÷ 40 = 6 L at the commercial ceiling and 240 ÷ 10 = 24 L at the maximum-stability one — four times the volume for the same 12 g of silver, which arrives four times more dilute. Note what the arithmetic does not say: the tighter standard does not remove more silver from the print, it retires the bath sooner so that the last bath a print meets is closer to fresh. The cost is bottles, shelf space and waste, and it is a reason to decide rather than to default.

Question 4. Your print fails the residual-silver test but the control sheet passes the residual-thiosulfate test. What does that pattern point to, and what does it rule out?

• A washing failure; it rules out a fixing problem
• A fixing failure — exhausted fixer, too short a fixing time, or a single bath worked past its capacity — and it rules out the wash as the cause, since the thiosulfate did leave
• A contaminated sulfide reagent; nothing is ruled out
• Both tests are unreliable on fibre paper and the result means nothing

Show the answer and why

Answer: A fixing failure — exhausted fixer, too short a fixing time, or a single bath worked past its capacity — and it rules out the wash as the cause, since the thiosulfate did leave

The two tests answer different questions and that is the whole reason the assignment requires both. Thiosulfate leaving the paper is a washing result; silver left behind in the paper is a fixing result, because the silver should have been dissolved and carried out by the bath before washing ever began. A wash cannot remove silver the fixer never dissolved. The remedy is on the fixing side — fresher fixer, two-bath working, or the capacity log honoured — and ILFORD's own instruction is to soak the print for five minutes and then repeat the recommended fixing and washing sequence in fresh fixer. One caveat belongs in the record: the sulfide test is not effective on a print straight from the fixer, so the result only means this if the print was properly washed first.

Question 5. Which of these belongs in the SOP itself rather than on the justification sheet?

• The sentence "a hypo clearing agent works by exchanging sulfite ions for retained thiosulfate, which is more soluble and diffuses out faster"
• The step "9. Treat in washing aid at 1+4 for 10 minutes at 18-24 °C with intermittent agitation. Waste: general chemical container."
• The note that Kodak's film sequence uses 1 to 2 minutes of hypo clearing agent while ILFORD's print sequence uses 10
• The reasoning for choosing a non-hardening fixer over F-5

Show the answer and why

Answer: The step "9. Treat in washing aid at 1+4 for 10 minutes at 18-24 °C with intermittent agitation. Waste: general chemical container."

Only the second is an instruction: imperative, numbered, one action, carrying its dilution, time, temperature, agitation and waste route. The first is a mechanism and belongs behind a link to the washing lesson. The third is a comparison between two published sources, and the fourth is a justification — both of them are exactly what the justification sheet exists to hold, one line each with the page that owns the argument. Keeping them out of the procedure is not tidiness: an SOP long enough to need skimming is an SOP that gets skimmed, and the step that gets skipped will be the one that mattered.

Check my answersClear