Fixer time, same for all films?

[dwdmguy]

Hi there.
I'm using the Ilford Rapid and keep my dilutation the same always.

Do I always keep my times of fixing (and stopping) the same even after developing different films on different days.
Thanks tons.

 

[drpsilver]

18 mar 2009

Hi there.
I'm using the Ilford Rapid and keep my dilution the same always.

Do I always keep my times of fixing (and stopping) the same even after developing different films on different days.
Thanks tons.

Dwdmguy:

The general answer is yes that most film will clear at approximately the same time. With this said the "tabular grain" films (Tmax and Delta) will take longer to clear and will exhaust the fixer more quickly. It is always best to keep the leader (cut from rolls before you process them) to test "clearing time" periodically. I keep a small box of leader cuts labeled with the film type so I can do the above test.

Hope this helps.

Regards,
Darwin

 

[srs5694]

My experience is very different from drpsilver's. In my experience, some films clear much faster than others. Foma films, for instance, clear very rapidly compared to other conventional-grain films (such as FP4+ or Tri-X).

Of course, that's just clearing time. If the "2x clearing time" rule is accurate, this translates into longer fixing times, but I can't promise this rule is really accurate. I personally fix for twice the clearing time or the recommended fixing time for the fixer in question, whichever is longer.

Note that clearing and fixing times increase as fixer is re-used, and so should be adjusted as you fix more films in a given batch of fixer.

 

[drpsilver]

18 Mar 2009

My experience is very different from drpsilver's. In my experience, some films clear much faster than others. Foma films, for instance, clear very rapidly compared to other conventional-grain films (such as FP4+ or Tri-X).

I have no experience with Foma films, only Ilford and Kodak.

Of course, that's just clearing time. If the "2x clearing time" rule is accurate, this translates into longer fixing times, but I can't promise this rule is really accurate. I personally fix for twice the clearing time or the recommended fixing time for the fixer in question, whichever is longer.

I agree, and do the same. Once I have determined the "clearing time" my fixing time starts at "2x the clearing time".

Note that clearing and fixing times increase as fixer is re-used, and so should be adjusted as you fix more films in a given batch of fixer.

I use the leaders of film to determine the "clearing time", and monitor how that time changes with fixer exhaustion.

Regards,
Darwin

 

[Don Wallace]

I do a clearing test with bits of unexposed film, then I fix for 2 x the clearing time. I also note the time when I first use the newly mixed fixer, and when the clearing time becomes twice that original time, I discard the fixer.

I can't remember where I learned that.

 

[Bob F.]

Everyone is mentioning "clearing time". For those unaware, the method is:

Put some of your fixer at working strength in a beaker - 100mm or so is fine and place a small piece of the undeveloped film in the fixer. Swish it around to simulate agitation in the tank (I always fix with constant agitation) and start timing. After 15-60 seconds you should see the colour of the film change from opaque to clear (usually with a slight coloured tint - ignore that). When it is clear, stop timing and note how long it took to turn clear. This is the clearing time for that make of film in thatfixer (at thattemperature). When processing the roll, fix the film for between two and three times the clearing time you obtained.

Typically you can snip a bit of film off the 35mm film leader to perform the clearing time test - or a few mm off the end of a 120 roll before you load it on the reel - just make sure it has not been developed first: the test needs to be on undeveloped film - exposure of the test strip to light is not relevant for the purposes of the test (obviously, do NOT expose the rest of the film to light until it has been fixed!).