Too much agitation when fixing film

[robert_ruderman1]

I suppose this is not a LF question, but more of general film developing question.

 

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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?

 

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Many Thanks...

[al______]

Should not really affect anything, unless it is insane over agitation.

[mike_rosenlof2]

I agree. Unless you're agitating so hard you physically damage the

film, there should be no problem.

 

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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.

[doremus_scudder1]

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)