Just wondering how you all keep track of the amount of film you put through your fixer. Before any of you say "I clip a bit of film and check the clearing time" you better explain that fully...
A 8 x 10 sheet is the standard for measuring the number of uses of fixer. A 35mm 36 exposure roll is equal to this. 4 4 x 5 sheets equal one 8 x 10. I just make a note as I go and dispose after a few weeks or the number of sheets have been fixed. I think fixer for what it does in very inexpensive compared to the failure outcomes. The instructions supplied with the fixer will give you the recommended usage rates. When I get busy I just place a white paper label on the bottle and place a line for every sheet I've done. The label washes off fairly easy. Hope this helps
Thanks Pat, that's the most practical way to go.
Shane, if you want to experiment re the clearing time test, just find a little piece of unprocessed film (eg the leader you cut off a 35mm roll) and dunk it in your fixer solution with a pair of tweezers. Hold it in there and watch what happens - the opaqueness clears. When your fixer is getting older and you are not sure whether to replace it, you can do this test. The common advice is that you need to fix for at least twice as long as it takes for the film to clear. (Practically, I do what Pat does and keep a tally of fixer uses.)
I use Ilford Rapid Fix, which only lasts (or, is only <i>meant</i> to last) a week once it's been diluted. I've never had issues with film not fixing properly (through any fault of the fixer at least!), I do, however, slowly increase the amount of fixing time as the days go by. Eg, on the day I mix it up, a 2 minute fix does the job, but if I don't use it for a few days, I might fix for 3 or so minutes the next run, at about a week, I'll go for the whole 5 minutes, plus a little more just to be safe. Like Pat said, fixer's cheap, so I'm never too fussed about mixing up a new batch if I'm suspicious.
Ian, interesting comment about fixing for twice as long as it takes to clear the film, I'm sure that tidbit will come in handy in the future!