Trying to read through instructions but can't decipher this. How long does one fix in Kodafix? My most common b&w roll films are Tri-X and FP4+. I am using HC-110 for development, and I mixed a 1:3 working solution from the Kodafix concentrate (125ml with 375ml deionized water).
I did an initial try yesterday at 4 minutes fixing, after a minute in the Kodak stop solution.
Fixing times depend on the film you are fixing. For Kodak products, you'll find the fixing time for Kodafix and other Kodak fixers in the data sheet for the film, e.g., Kodak recommends 2-4 minutes for Tri-X in Kodafix. For T-Max films, Kodak recommends 5-10 minutes.
From this, one can extrapolate that "conventional" films can be fixed for the shorter times, newer tabular-grain films (i.e., T-Max or Delta films) need the longer times.
Kodak also recommends using the clip test and fixing films for at least twice the clearing time. Clip tests are easy, but you need to do them every time you fix if you re-use your fixer, since clearing times change as the fixer becomes progressively more and more exhausted (that means, don't use twice the clearing time in fresh fixer to fix the next batch through the fixer, since that time is no longer valid; you need to do a new clearing test to arrive at the new time). Your fixer will need to be discarded when the clearing time reaches twice that in fresh fixer, so make good notes.
That said, it has been well established that fixing film longer than the minimum twice the clearing time has no ill effects as long as that time isn't excessive enough to cause bleaching. So (stay with me here) since you can fix film in fixer that has just about reached the exhaustion point, which is 2x the clearing time in fresh fix, by doubling that time, the "maximum" time you'd be fixing before mixing fresh fix would be 4x the clearing time.
So, one can simply do a clip test for a given film in fresh fixer, take that time and multiply it by 4, and arrive at a time that will supposedly work for all your fixing needs for a given film. I take this a step further and add a bit of a safety factor, roughly 20%, just to be sure. That much fixing will not damage any film.
So then, you can use one fixing time for a given film until you need to mix fresh fix. You still have to keep track of your throughput capacity and clip-test your fixer as it nears the end of its useful life to determine when the clearing time approaches 2x that in fresh fix so you can mix new. Or, you can keep track of this once, note the capacity, figure in a safety factor by reducing that capacity, say 10%, and then just keep track of throughput.
This latter, along with the 4x clearing time in fresh fix plus the safety factor, is what I do. Say it takes one minute for my film to clear in fresh fix. The "universal fixing time" for that film would then be 4 x 1 minute + 20%, which works out to 4 min., 48 sec. I'd likely round this up to 5 minutes and be done with it. Then, every time I fix that particular film, I simply give it 5 minutes; no clip test and re-calculating fixing time every session.
Do this once for each type of film you use and figure out the throughput capacity so you don't overuse your fixer and you'll save a lot of time and gain peace of mind.
Best,
Doremus
