Too much agitation when fixing filmgreenspun.com : LUSENET : Large format photography : One Thread
I suppose this is not a LF question, but more of general film developing question.
From reading Adams' book on the negative, it is quite evident on what are the consequences of over agititation with developer in the tank. But what are the consequences of over agititation with fixer in the tank? How does it affect the negative?
-- Robert Ruderman (email@example.com), July 06, 1999
Should not really affect anything, unless it is insane over agitation.
-- Altaf Shaikh (firstname.lastname@example.org), July 07, 1999.
I agree. Unless you're agitating so hard you physically damage the film, there should be no problem.
I hear you can over fix film, and vigorous agitation might shorten the time that would be considered over fixing. But over fixing is usually several times standard fix times, not an extra 30 seconds in the fix.
-- mike rosenlof (email@example.com), July 07, 1999.
Robert, In the same Ansel Adams book you mention you will also find a small reference to the fact that fixer works a bit more efficiently with less agitation. It seems the silver halides dissolve out more quickly when there is an undisturbed interface between solution and print/film surface and only slows down after the solution in direct contact with the surface has a significant saturation level of dissolved silver compounds. Then it needs an agitation to bring fresh solution into contact with the emulsion (once each 30 seconds should be more than adequate). Subsequently, too much agitation can slow down fixing to a certain degree. However, this effect is very small and in practice can be ignored. Overfixing, especially with rapid fixers that contain ammonium thiosulfate, can lead to a reduction of density in the negative as the fixer will begin to dissolve the metalic silver which forms the image with excessive fixing times. This, however is mostly a matter of time and not agitation. More important is fixer exhaustion, which leads to underfixing and is a separate issue. Watch the capacities, time and temperature carefully, and don't worry too much about your agitation. If you do everything the same way every time and your negs and prints pass a residual silver halide test then you will be assured of repeatable results. Hope this helps, ;^D)
-- Doremus Scudder (ScudderLandreth@compuserve.com), July 07, 1999.