Darkroom opening and closing for a printing session

Purpose

To put the room into the state the printing pages assume — dark to the standard its certificate names, lit only by a lamp with a measured safe working time, nothing else emitting — and to take it back out without fogging what is left.

When to use it

At the start and the end of every session in which paper leaves its packet under a lamp. This is the light half; opening the laboratory and closing it are the chemistry half, each run from inside this one at the step that names it.

It assumes a leak-test verdict and a material class from making a room dark, and a measured figure for the lamp from testing a safelight; it produces neither. Where the room is somebody’s bathroom for the rest of the week, closing takes the blackout down.

Before you start

You should already have the room’s certificate card — its date, the material class, and the hour if the blackout depends on the sun; your safe working time for the lamp at the distance it will stand, from the fog limit; and the aperture, magnification and warm-up rule on the enlarger’s certificate.

In the room: the blackout panels or fabric and the door, threshold, keyhole and letterplate seals; a watch you can read in the dark, and no phone; the paper still boxed; the safelight on its tested mounting; trays, tongs, thermometer; a white A4 sheet and a dark background; the card and notebook.

Level A on the classification rubric: tray-strength chemistry, nothing weighed, heated or wired. The hazards are the dark, a step ladder if a panel goes up high, and powered equipment in a room with water in it.

Procedure

Opening

1. Read the certificate first. If tonight’s material is faster than the class on the card, the room is not cleared for it.
2. Open the air path before the blackout goes up: the light-trapped vent, or a trapped extract for a long session. ILFORD’s answer for occasional use is to open the room up between runs.
3. Fit the blackout — panel or fabric with its overlap, the compression seal at the door stop, the brush at the threshold, flaps over the keyhole and letterplate.
4. Kill everything else that emits: timer display, indicator LEDs, charger, router, clock face, smoke alarm, the gap at the enlarger’s lamphouse — Kodak name the lamphouse, lighted dials and pinholes as the ones usually missed. The phone goes in another room.
5. Set the room out one way, wet side and dry side, as the layout lesson has it: paper stock in the dimmest corner, no direct safelight on the easel.
6. Plug into the residual-current device, run leads high, keep powered items out of the splash zone. HSE are plain that 230 V can kill, worst in wet surroundings.
7. Run opening the laboratory now. Whatever can be done in the light is done in the light.
8. Switch the enlarger on and start its warm-up clock. Set the aperture and magnification the certificate names.
9. Turn the room lights off. If any are fluorescent, wait five minutes: the tube keeps glowing after the switch.
10. Sit still for twenty minutes, safelight off as well: Kodak put full adjustment of the eyes at ten minutes and ILFORD at about fifteen.
11. Sweep in order: door edges, threshold, keyhole, sill, top corners, vent, ceiling, every device. Close with Kodak’s white-paper check — a white A4 sheet against a dark background at arm’s length. Visible means not dark.
12. Switch the safelight on, and confirm it is on the mounting and at the distance it was tested at. Write the safe working time where you will see it.
13. Open the paper by handling paper in dim light, and start its clock.

Closing

14. Last sheet into the fixer. Fold the bag, close the box, put it away before anything else.
15. Say out loud that the light is going on. Then switch it on.
16. Finish the prints by the archival sequence. A session cut short hands its prints to storing unfixed prints.
17. Enlarger off, lens capped, carrier closed. Let the head cool before covering it.
18. Safelight off, and add the session’s hours to the filter’s log: ILFORD ask for the installation date recorded and the filter changed each year.
19. Run closing the laboratory: waste to its streams, vessels washed in family order, the first silver-bearing rinse collected, gloves off by the sequence.
20. Take the blackout down if the room is shared, and open the window and door to air it.
21. Update the certificate if the room changed, and write the notebook line at the bench.

How you know it worked

• The white sheet was invisible at twenty minutes adapted, and nothing in the room glowed.
• The paper box was closed and away before the white light went on, both times.
• Print borders are white and highlights clean; flattened contrast, not visible fog, is the first symptom of a room that is not dark.
• The lamp stands where its test says, and bag-to-fixer time was inside the figure beside it.
• The room is aired, the blackout is down if it had to come down, and the card carries today’s date if anything moved.

If a step fails

Step 1, no certificate, or the material is faster than its class. Run the leak test on making a room dark first. Until it has been run the room is cleared for paper only, and film is loaded in a changing bag.

Step 3, a seal will not hold. Small leaks take black tape and large ones heavy cloth, which is Kodak’s own instruction. A leak you cannot close moves the session to the hour the blackout does work.

Step 4, an emitter that cannot be switched off. A smoke alarm’s indicator stays. Tape a matt black card over it rather than removing the alarm; keep the card with the panels.

Step 10 or 11, the white card is still visible. Do not open the paper. Hunt it with the torch reversal — somebody outside walking the door and window with a bright torch while you watch. If it is not found, work from a changing bag and read room light leak.

Step 12, the lamp has moved since it was tested. Its verdict is void. Put it back, or hold to the shorter of your last figure and the maker’s limit — ILFORD’s is four minutes of direct illumination at not less than 1.2 m — and re-test before next session.

Step 14, the white light went on with paper out. Every sheet out of the box is a test strip now. Process one and look at its borders; if they are grey, read safelight fog.

Step 20, the blackout must come down and you are too tired. Take down only what stops the room being a room — the threshold seal and the door flaps — leave the panels, and write on the card what is up.

What to record

One line at each end. At the start: the date and hour, the material, the light you work under as filter, wattage and distance, the safe working time you hold to, and anything on the opening list that was not true. At the end: bag-to-fixer time, sheets out against sheets back, the enlarger settings, the filter hours, and anything you changed about the room.