Simple (but important) question:

Any views on the ideal duration of film washing after a film has been developed, stopped and fixed? I tend not to use hypo-clearing agent, and just go for a straight wash in running water using a force film washer.

-- Ed Hurst (BullMoo@hotmail.com), January 29, 2002

Answers

Ed, I use distilled water for all the steps in film processing including the final rinse, thus the water economy is important for me. I started with the procedure outlined by Ilford in their data sheets (drain/refill several times). But I wanted to be sure it gives an efficient washing. I did some calculations (a simple task about several dilutions) and found that five steps are enough assuming 2 conditions kept true:

1) The time for each step is long enough to allow the diffusion process to be completed

2) The amount of the solution carried to the next step is minimal. The calculation showed that this amount greatly affects the wash efficiency.

Practically (for 2 reels tank) it means:

1) 1 min, 5 min, 10 min, 15 min --- times of each step. With occasional agitation. Plus final treatment in photo-flo in a separate tray.

1) I carefully shake off the reels with films and the tank (the lid is removed after fixing) to keep the amount of carried solution as small as possible.

I use this procedure already 2-3 years, and all my films are ok. Even though this time is not sufficient to experimentally prove the archival performance :)

-- Andrey Vorobyov (AndreyVorobyov@yahoo.com), January 29, 2002.

It depends on the fixer you use. If you use TF-{3,4} or Ilford Multigrade fixer type of rapid fixers, 5 min is probably very safe. Washing out fixer is a diffusion process and good agitation is important.

I rinse the film, reel, and the tank and fill up the water, agitate a few times, dump water, repeat for a couple of times, and put the films in running water film washer for a few minutes. (Basically, first half of Ilford film washing method.) This way, I can minimize water wasted because all I need is a continual water motion, not the replacement of water, as residual fixer level in the water is already very low even if I keep using the same water.

Some argue prolonged wet time increases the grain. I am not sure if it is a reliable observation/comment. But I think wet time is less important compared to paper.

For technical information on fixing and washing, see Fixer for film and paper.

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), January 29, 2002.

Andrey,

Do you have problem with your tap water? Water impurities (like dissolved salts and other ions in sea water) help washing out fixers so I would use tap water or even sea or well water for washing and then use distilled water for final wash. I use Agfa Sistan as the wetting agent diluted in d.water for the final step.

As you pointed out, a long time is necessary for fixer and silver complex ions to diffuse out of gelatine, but good continual agitation really helps to speed up the process. A bit of water carried over is not a big issue with good agitation.

If you use acid fixer or even worse acid hardening fixer, the whole thing takes a lot longer time.

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), January 29, 2002.

Ryuji,

yes, I probably have problems with tap water. When I started photography I tried to use plain tap water. The result was hours of retouching the prints. I tried a variety approaches: I used filtered water, I used distilled water for final bath only (after rinsing), -- all this only _partially_ removed the dirt. When I switched to distilled water it solved the problem completely: my negatives are absolutely clear; I almost never need to retouch, only if I have missed a tiny dust spes while enlarging.

Yes, I know that some salts dissolved in rinse water speed up the removing the products of fixations; the 2% solution od Na2SO3 (Sodium sulfite) is a cheap and one of the most efficient means; by the way Kodak hypo clearing agent consists almost entierly of this substance (in spite of some additions intened for hard water). And I've used sometime this 2% solution bath immediately after fixing, but I could not detect any difference: I fix carefully, and 5 steps mentioned above were pretty enough.

"A bit of water carried over is not a big issue with good agitation." -- Ryuji, I'm not sure if I described my procedure clearly enough. I don't use running water (there is no running distilled water supply), I use static procedure: I fill the tank with water, wait agitating, drain, then refill. This cycle repeats 5 times. My point was the more water you carry over to the next step, the less efficient becomes the procedure, in other words 5 cycles can be not enough. If you're curious, I can email you the formulas showing that if we increase the carry over amount, the efficiency of the wash drops, and drops greatly.

Regards Andrey

-- Andrey Vorobyov (AndreyVorobyov@yahoo.com), January 29, 2002.

In increasingly rarer occasions when I process 35mm films, I wash in the way Andrey described, except with tap water. I simply put the tank lid on and invert agitate between filling and dumping water. What I meant was that with good agitation, shaking off remaining water is not all that important. The thiosulfate concentration in the water is already very very low after two cycles, and the concentration gradient drives diffusion weakly while agitation drives much more strongly. That's what I meant.

The reason I switch to continual flow washing with 120/220 format is because I want to sit down and get my hands off for a while after shaking a big tank. I think fill and dump method is just as good.

I think fixer washing aid solution often mixes bisulfite or metabisulfite in addition to sulfite to prevent possible mineral deposit with hard water as well as preventing excessive swelling of gelatin. Either way, not a big deal in most cases.

It sounds like you have a problem with grit or something in your tap water. If you have a microscope just take a piece of neg to look at what's the dust-like substance you get on the neg. It might be some mineral deposit or grit. Someone brought in some strangely dustly negative for me to look at, and it was tiny pieces of gelatin came off from the film. Under a microscope, you often get much better idea of what it is!

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), January 29, 2002.

I haved read in some place or other that washing film in pure distilled water is a recipe for disaster. Distilled wash water should be conditioned with Kodalk first, (2% maybe?)

Personally, I use Koday Hypo-Clear, and then continous agitation for five minutes, two replacements of water during that. My earliest 35mm negs go back to 1956 and last I looked, they were still there.

-- Richard C. Trochlil (trochlilbb@neumedia.net), February 15, 2002.