Hi What is the optimum number of films that Hypam/Ilfostop can be used for before they expire? I have had diluted solution working for perhaps 8 weeks and have been developing 2 films a week? Many thanks in advance Andrew

-- Andrew Buckley (da_buckley@yahoo.com), December 17, 2000

Answers

The way I check fixer life is to put a cut off end of film in the fixer when it is freshly made. I time how long it takes to clear. I fix for at least twice as long as this time. I write that time on the bottle.

As I reuse the fixer, I keep dropping the cut off end into a bit of fixer and time it. When it takes twice as long to fix as it did in fresh fixer, it is time for fresh fixer.

For stop, I use indicator stop and use it until it turns color, or I get tired of using the same stop. I mix my stop for film a 1/2 the recommended strength to avoid pinhoes.

-- Terry Carraway (TCarraway@compuserve.com), December 18, 2000.

Everytime I buy a bottle of Hypam, it comes with a nifty little booklet that gives instructions and capacities. Perhaps the information you are looking for is there. I suggest you read it if you have it.

-- Doremus Scudder (ScudderLandreth@compuserve.com), December 18, 2000.

Thanks for the contributions. Regrettably Ilford do not publish the details i'm looking for on the bottles-well not in the UK-hence the question. Interestingly i noticed that other contributors have talked about T-Max and the 'purple fog', and this is the reason that i felt that the Fixer/Stop Bath may have been exhausted. Certainly on mixing new stock the film was clear-but i'm now wondering whether more than one problem occurred. As ever any advice, and many thanks in advance. Andrew

-- Andrew Buckley (da_buckley@yahoo.com), December 18, 2000.

Ilford does not give information regarding the number of films that can be fixed per volume of fixer, and Terry's advice accurately reflects their recommendations. I always mix 2 liters of rapid fix and never fix more than 40 rolls of film in it. I put a piece of black tape on the bottle and make a mark on it for every roll I process. For my purposes, each mark counts as one 8x10 piece of film. One roll of 35mm, one roll of 120, or four sheets of 4x5 equals one sheet of 8x10, equals one mark. Ilford states that as the fixer is used, the fixing time increases, but I've always simply used 2 minutes (exept for T-Max, where I use 3 minutes). This is a very conservative use of the fixer, as Kodak states that their rapid fixer (1:3) will fix 32 sheets of 8x10 film per quart. Kodak also states that the 1:3 working solution will keep for two months in a stoppered bottle.

For paper, I use two fixes, each of 2 liters, the second fix becoming the first fix after 60 8x10 prints (or equivalent).

In regard to Kodak indicator stop, Ansel said that by the time it changes color it has ceased to be an effective stop bath. So I use acetic acid, as it is cheaper. We have a dealer in town that stocks the glacial, so that is what I buy, as it is MUCH cheaper. A gallon of glacial acetic acid will last me several years.

-- Ed Buffaloe (edb@unblinkingeye.com), December 19, 2000.

Ed,

Actually I agree that the indicator in indicator stop may not be as accurate as we like. The strange thing is there is a similar chemical that does color change at a slightly lower pH, and I have no idea why they don't use it. From chemical suppliers it is about the same price.

For film, I don't worry too much, since plain water works well as stop, and the indicator will change by the time it reaches pH 7.

-- Terry Carraway (TCarraway@compuserve.com), December 19, 2000.

Testing with the leader, as mentioned above, is a good idea.

The generally accepted rule of thumb is this: you should fix for double the time it takes for the film to clear. When the time to fix the leader becomes double what it is with fresh fixer, you need new fixer.

For example ... if you need a 2:15 fix to clear the leader, use 4:30 for the actual roll of film, but when your future leaders of the same type need 4:30 to clear, your fixer is done and you should discard it.

-- Jim MacKenzie (photojim@yahoo.com), December 19, 2000.