Handling and storing a deliberately faulty reference specimen

Purpose

To make a fault on purpose, under known conditions, and keep it in a way that tells you afterwards what produced it — without letting it damage the work it stands beside.

When to use it

Whenever a fault is reproduced deliberately and the result is kept: a safelight-fogged sheet, an under-fixed print, a strip developed short. It applies from the moment the specimen is made until the day it is retired.

A specimen you made is calibrated and a plate in a book is not, which is why the course prefers one. The diagnosis lab makes that argument; this sheet is how the object is handled.

Before you start

You should already know that residual thiosulfate can migrate to prints stored in contact with a sheet that carries it, from the permanence lesson.

Level A. Working-strength developer, stop, fixer and wash at the published dilutions, in ordinary trays at room temperature: nitrile gloves, eye protection, ordinary ventilation, tongs, one dedicated vessel per bath. Where you confirm the specimen with a residual-silver test, the sulphide reagent is kept away from every acid on the bench by layout rather than by care, under the test procedure.

On the bench: a sheet for the specimen and an identical sheet for its control; a masking card; a pencil; the timer; individual sleeves and envelopes, labelled before the session rather than afterwards.

Procedure

Making it

1. Decide what the specimen is meant to show, and write the sentence down before you expose anything.
2. Start the series from a published condition rather than an invented one — a maker’s stated safe time, a maker’s stated fixing time — so that every step of the series is a multiple of something a reader can look up.
3. Make the control at the same time: an identical sheet given everything the specimen gets except the one variable, processed in the same dish at the same time.
4. Isolate the variable. For a safelight specimen, the enlarger is off and the room otherwise dark, or you will measure a lamphouse leak and call it the safelight.
5. Run the series past the safe end, in doublings, and if nothing shows, double again and record what it took. The specimen is made when a band shows, and the time it took is the datum.
6. For a fixing specimen, wash all the sheets fully and identically. A shortened wash adds a second variable and reproduces an ambiguity on purpose.
7. Confirm what you made with a test rather than with an opinion: read the residual-silver spot on each sheet against the fully fixed one, by the test procedure.
8. Dry every sheet together, by one method, and route the spent developer and the silver-bearing fixer to their own containers. Check your local regulations, which govern both routes.

Labelling and storing it

9. Label each sheet on the back in pencil with the series step, and label the envelope in full.
10. Put on the envelope: what it is, why it is faulty, the parameter that made it, the date, and the sentence this is a reference specimen and not a print. Somebody else will open that box one day.
11. Add the conditions nobody could reconstruct: paper and box code, safelight filter and its installation date, bulb wattage and distance, or the fixer, its dilution and its running total.
12. Sleeve an unstable specimen on its own and put it in its own envelope, away from finished work. An under-fixed print carries residual thiosulfate and residual silver by design, and it can reach a neighbouring sheet.
13. Store the envelope where it will actually be picked up — in the darkroom, beside the enlarger, not in a book in another room.
14. Photograph or scan an unstable specimen at intervals, because it will not stay comparable to its own earlier state.
15. Re-read it against its control once a year and record what has changed.
16. Retire it when it stops showing what it was made to show, and note the date and the reason.

How you know it worked

• The specimen shows the fault unmistakably, and its control shows none.
• Every number on the label is a measurement rather than an intention, including the one that says how far the series had to run.
• The envelope names the specimen as a reference and says why it is faulty.
• An unstable specimen is sleeved alone and stored away from finished prints.
• The test result that confirms the fault is written down beside the parameter that produced it.

If a step fails

Step 4, the fault appears on the control as well. Then the variable was not isolated and the specimen is worthless as a reference. Find the second source — a lamphouse leak, a door, a luminous dial — before you make another.

Step 5, nothing shows at the end of the series. Double again on a second sheet and record what it took. A lamp that shows nothing at four times the published limit is a better lamp than the recommendation assumes, and that number belongs on the label.

Step 6, the sheets were washed differently. The specimen now carries two variables and cannot attribute either. Make it again rather than reasoning about which caused what.

Step 7, the confirming test disagrees with the appearance. Believe the test and record the disagreement. Two false positives are on record for the residual tests, and an entry that names them is worth more than one that quietly picks the answer it wanted.

Step 10, the envelope carries a title and nothing else. It is not a specimen yet, it is a spoiled print. Add the parameters now, while you still remember them, and mark them recalled after the fact if you are reconstructing.

Step 12, an unstable specimen has been filed with finished prints. Take it out, sleeve it separately, and inspect the sheets that were touching it. That migration is a slow accident, and it is the reason this sheet exists.

Step 15, the annual reading shows it has changed beyond use. Retire it with a note of the date and the change. A reference that no longer shows the fault is worse than none, because it is still consulted.

What to record

On the envelope: what the specimen is, why it is faulty, the parameter that produced it with its units, the date, the paper and box code, the processing, and the words that say it is not a print. In the notebook: the sentence from step 1, the series and where it landed, the control’s behaviour, the confirming test result, and each annual re-reading with the date. And, when you write it up, cite the specimen by its parameters — a stated fixing time on a named paper against a named control is evidence; under-fixed prints go yellow is a rumour.