Fixer questions, and in particular, “How long does it take to fix a film”, are our most frequently asked technique enquiries. As a rule of thumb, you should aim to fix a black and white film for twice the amount of time that it takes to clear it. You do this by simply taking your film leader (cut off the film strip before putting onto the developing reel). Take this small piece of film and place it in the lid of your developing tank. Pour in some of your ready-to-use fixer to cover the film leader. Then time how long it takes for the film to go completely clear - with no purple tinge. Doubling this total time will give you the actual time you need to fix your film for.
Therefore, if the film is clear at 2 minutes then fix for another 2 minutes. If it is still cloudy then fix for another minute or so and check again. The difficulty in manufacturers putting information on fixing bottles is that the total fixing time is not precise and depends on the fixer and the film used . We reuse our fixer until it is exhausted. The effectiveness of your fixer chemical will deteriorate over time as it is re-used so this test should be re-done when you've used 8 or 9 rolls. We usually use about 500ml of fixer to fix about 12 36 exposure rolls of film.
23rd March 2012