Collecting and segregating waste across a multi-run session

Purpose

To get an evening that ran four developers, or one developer twenty times, into four or five containers that each say what is in them — decided before the first tank is filled rather than at midnight.

When to use it

Any session that runs more than one developer, or the same one repeatedly: a comparison, a time series, an exhaustion arm, a bracket. A single-developer film session is covered by general chemical waste and silver-bearing waste, and this sheet does not restate them.

Before you start

You should already have read the disposal caveat and checked what your own authority accepts. Local regulation governs, it differs between authorities and it changes. Check your local regulations.

Level A as a routing procedure, inside sessions at their own levels — a session that weighs its agents is Level B while the balance is out, by the weighing sheet. Gloves and eye protection stay on until the last container is capped.

The rule that shapes the corner: the alkaline developer stream and the acidic silver-bearing fixer stream are never combined. Mixing them spoils the recovery as well as the record, and the two liquids are adjacent in the tank sequence and adjacent again in the waste corner, which is why this is the likeliest incompatibility accident in a home darkroom.

And a staining developer is its own stream. Pyrogallol carries harmful to aquatic life with long-lasting effects, and its own page’s instruction is that its solutions and its rinse water are collected rather than drained.

On the bench: one labelled container per stream, standing apart, open, before the first tank is filled; a funnel per container; the session log with a column for volumes.

Procedure

1. Write the stream list down before you mix anything. A four-developer evening usually makes four: spent film developers; spent staining developer and its rinse; spent fixer and the first rinse after it; and spent paper developer, which is a different bath from the film ones.
2. Label a container for each, in words, by the labelling procedure, and give each its own funnel.
3. Stand them apart, with the alkaline and acidic containers at opposite ends of the corner.
4. Open every one of them before the first pour.
5. Pour each developer into its stream as it comes out of the tank, not into a holding jug to be sorted later. A jug is an unlabelled container the moment you put it down.
6. Keep a one-shot developer’s volume and a re-used one’s volume as separate lines, because the second carries the whole session’s oxidation and the first does not.
7. Put the staining developer and its rinse water into their own container, and rinse its tank into that container too.
8. Put spent fixer and the first rinse after it into the silver-bearing container. In a session that passes both film and paper through one fixer, that stream is unusually rich.
9. Keep the paper developer out of the film-developer container. It is a different formula at a different dilution, and merging them destroys the only record of how much of each you used.
10. Where an arm of the experiment deliberately ages a developer in a part-full open bottle, label that bottle with the words deliberately oxidised and its date, and store it where it cannot be mistaken for working solution.
11. When that arm ends, route the aged bottle to its own stream and record how long it stood.
12. Collect the wash water rather than draining it, and say on the label what it is the tail of.
13. Cap each container, wipe its outside, update its running-volume line and add the date.
14. Rinse each funnel into its own container and store it with that container.
15. Enter the volumes in the session log against the version identifier of each bath, and take the containers by the route you checked and dated.

How you know it worked

• The stream list was written before the first bath was mixed, and every container was labelled and open before the first pour.
• Nothing was poured into a jug to be sorted afterwards.
• The alkaline and acidic containers stand apart and neither has gained the other’s contents.
• The staining developer’s rinse water is in the staining container, not in the wash stream.
• Any deliberately oxidised bottle is labelled as such and stored away from working solution.
• Each container carries contents in words, a running volume, a route and the date the route was checked.

If a step fails

Step 1, the session made a stream you had not planned for. Label a container for it now, before you pour. An unplanned stream tipped into a planned container is how a container becomes an unknown.

Step 5, two developers went into one container. Record the merge and the approximate volumes. The waste route is unlikely to care; the log does, because the litres you have used of each formula are part of the exhaustion arithmetic.

Step 7, the staining developer’s rinse went down the drain. Record it with your estimate of the volume and move the container before the next run. The entry changes the habit; the container’s position makes the habit possible.

Step 8, developer has gone into the fixer container. Say so on the label and treat the container as mixed thereafter. Do not decant it to separate them: an alkaline sulphite solution in an acidic silver-bearing one is a spoiled recovery, not something to be undone at a sink.

Step 10, the aged bottle has no label. It is an unknown, and the unlabelled container procedure governs. A bottle of deliberately oxidised developer that gets used as stock costs a whole arm of the experiment.

Step 13, a container fills mid-session. Cap it, date it, start another. Never decant into an unlabelled bottle to make room.

Step 15, your authority does not accept a stream. It stays capped, labelled and in its tray while you find one that does.

What to record

One line per container: date opened, stream in words, container and size, date closed, running volume, route and the date the route was checked. Then, in the session log rather than on the bottle, the volume used of each named bath against its version identifier — that is the figure a capacity or an exhaustion result is computed from, and it cannot be recovered afterwards from a bottle of grey liquid.