Film Fixer Clip Test & alternative Film Fixing Procedure-for Black & White Negatives

MattKing submitted a new resource:

(there was a url link here which no longer exists) - Film Fixer Clip Test & alternative Film Fixing Procedure-for Black & White Negatives

Here on APUG we regularly have questions come up about film fixing, and the answers often involve a “clip test”, but sometimes it isn’t clear to everyone what is meant by a “clip test”. With that in mind, and to save typing, I decided to post this in the Articles section.


FILM FIXER CLIP TEST (to test for clearing time):


1) take a scrap of undeveloped film (a piece of 35mm leader is fine). I like to use TMax 400, because it takes the longest time to fix of all the common films;
2) put a...

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(there was a url link here which no longer exists)

In addition, I use a slightly unusual procedure for fixing film, which is well suited to those who have small spaces, and temporary darkrooms, so I thought I would share that as well.

MATT KING’S PROCEDURE FOR FIXING FILM

I have very limited storage space, and my darkroom is temporary. For that reason, I take steps to minimize the storage space used. To that end, I use liquid chemicals, including fixer, and try to use no more than two moderately sized bottles (concentrate and working solution) for chemicals that are re-used (such as fixer).

For fixer, I’ve used Ilford Rapid Fixer, Ilford Hypam and, currently and in the past, Kodak Rapid Fix. I don’t add the hardener to the Kodak Rapid Fix. I’m currently using a 1.25 litre bottle of 1+4 working solution Kodak Fixer. Here is what I do:

1) I keep one bottle for my film fixer - it is large enough to run at least two separate batches of film at the same time;
2) a) I pour one batch of fixer into my film developing tank at the start of the fixing stage, and agitate normally (in my case, on a rotary agitator); and
b) at the same time, I do a clip test with T-Max film;
3) When the clip has cleared, I dump the first fixer into a graduate, and pour the second batch into the tank. I then fix for the same time as the first run, but this time in the somewhat fresher fixer;
4) After use, all the fixer goes back into the bottle - although I will consider filtering it if necessary.

I continue to use that fixer until the earlier of:
a) I have fixed enough film to have reached 2/3 of the manufacturer's recommended capacity for that volume; or
b) the clearing time reaches twice what the starting clearing time was,
at which time I take it over to friends' place, where they are reclaiming silver from their fixer (they have more space, and use more fixer).

I put masking tape on the bottle, and mark it with the initial clearing time and a "/" for each roll fixed.

If I had more room, I would use two separate bottles, and the two bath fixing regime.

thank you matt !

Matt, what is the purpose of doing two baths in the same batch of fixer? Usually two bath fixing is done with a fresher batch of fixer as the second bath.

grain elevator said:

Matt, what is the purpose of doing two baths in the same batch of fixer? Usually two bath fixing is done with a fresher batch of fixer as the second bath.

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It is at least partly rooted in the fact that I use relatively small quantities of fixer and continuous rotary agitation.
I am trying to avoid a situation where the fixer starts out with a fair bit of capacity but is at least partially exhausted before the film is fully fixed. The concern arises mainly due to the relatively small volume of fixer used each time when using continuous rotary agitation. I sometimes fix four rolls of T-Max at a time, in just 600 ml of fixer. The second bath adds 600 ml of fixer half way (or a third of the way) through the time, and those 600 ml are a fair bit more "fresh" than the first bath is after it has done most of the fixing work.
Mostly though, it is because of how it influences the workflow - it really reinforces the two (or three) times the clearing time approach.

I see, that makes sense. Maybe add this info in the overview? Could otherwise confuse people, as if you work with standard volumes of fixer per roll, it's pointless.

grain elevator said:

I see, that makes sense. Maybe add this info in the overview? Could otherwise confuse people, as if you work with standard volumes of fixer per roll, it's pointless.

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It continues to have its value even if you can use larger volumes because of the workflow, but remember the included qualification:

MattKing said:

I have very limited storage space, and my darkroom is temporary. For that reason, I take steps to minimize the storage space used.

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and

MattKing said:

If I had more room, I would use two separate bottles, and the two bath fixing regime.

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MattKing said:

It continues to have its value even if you can use larger volumes because of the workflow [...] -

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Sorry, I don't see it. No advantage over fixing in just one bath then. You end up using a second bath that has very nearly the same degree of exhaustion as the first bath. If it will be good enough as the "second bath" for the next film you process, why is it not good enough to fix the film you're processing now in one go? Or, if you have a very large volume of working solution, for the film you will process in two weeks, when the whole of the working solution will be as exhausted as your "first bath" from now? It's really only a concern if the working amount in the tank is so little it could get exhausted. The amount of working solution needed to just cover one film can fix at the very least 3-4 films, so it just doesn't happen with inversion agitation.

grain elevator said:

But even 100ml of working solution can fix 1-2 films, so it just doesn't happen with inversion agitation.

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It might very well make a difference when I am fixing four rolls of T-Max in 600 ml and I have previously used the 1.25 litres of fixer to fix 24 other rolls of film.
More importantly though, it fits with my small space, small bottle, small quantity of fixer, integral clip test work flow. So I share it here for people to consider.

Oh no, I got caught ninja editing... what you quoted isn't there any more, tried to make it clearer, but the ratio stands. Sure, it might make the difference for the last bit of the fixer capacity. In which tank can you fix four rolls with inversion agitation in just 600ml? I think that's still a number that only applies for rotary.