Affect of temperature on fixer

[bobwysiwyg]

I've been using fixer time (fresh fixer by the way) as documented by Kodak. I wondered though, does temperature alter its ability to clear based on temp similar to the affect temperature has on developer?

 

[Sirius Glass]

I would thing that as the temperature of fixer drops from 68°F [20°C] that the reaction time increases, but not a great deal. I would think that even with the solution ionization lowering the freezing point, that at 23°F [-5°C] that the reaction time would be much s-l-o-w-e-r.

 

[Gerald C Koch]

Fixing is a mainly diffusion controlled reaction so temperature should not have that great an effect on it.

 

[georgegrosu]

I believe diffusion have an important role in photographic processes.
Fixer is a total reaction and temperature and time are not critical.
Fixer time is made during the clarification of the film plus
time required for chemical products formed to diffusion the film in fixer ( x 2 time of clarification).
It is best to follow the prescribed temperature.
From a practical standpoint, plus or minuc few degrees C for fixer is not a catastrophe.
A better agitation of solution fixer can compensate for the absence of several degrees.

George

 

[bobwysiwyg]

Thanks for the replies everyone.

 

[Nicholas Lindan]

A general rule-of-thumb is that things take twice as long for every drop of 10C and vice-versa.

The 2x/10C number comes from the Arrhenius equation at room temperature for simple processes that are limited by diffusion and the collision rates of the reaction components:
http://en.wikipedia.org/wiki/Arrhenius_equation

A discussion/rebuttal of the the 2x/10C applicability:
http://antoine.frostburg.edu/chem/senese/101/kinetics/faq/print-temperature-and-reaction-rate.shtml

 

[EASmithV]

So, if one were to do a bleach bypass on some E6, they would not heat the regular fix?

 

[RalphLambrecht]

there is a well-known ilford chart showing the dev time change according to temperature, but it does not follow the arrhenius equation;does anybody have an idea why?btw the ilford chart works very well in my experience.

 

[ic-racer]

there is a well-known ilford chart showing the dev time change according to temperature, but it does not follow the arrhenius equation;does anybody have an idea why?btw the ilford chart works very well in my experience.

(there was a url link here which no longer exists)
(there was a url link here which no longer exists)

 

[Aristotle80]

I have an important warning about Kodak's liquid fixer concentrate and cold temperatures. For a time I had my photo chem in a backyard shed with no climate control. It dipped into the 40s for around two weeks. The next time I checked the chem the fixer was destroyed. (The developers were all fine.) A thick sludge precipitated out of solution and it looked so funky I wasn't confident about using it again. I tried stirring up the sediment but it didn't remix. The concentrated fixer was unmixed and uncontaminated since I don't dilute it for use all at once.

So while temp doesn't drastically affect fixing times, be careful about cold storage conditions.

(I'm not a chemist and I don't even play one on the internet. I've done BW constantly since the 90s and I'm generally pretty careful with my process. It's the only time something like that has ever gone horribly wrong for me.)

 

[Gerald C Koch]

Diffusion controlled reactions can be very complex. One must take into consideration among other things the shape of the ions or molecules, their electric charge, the composition of the substrate, etc. A molecule containing a bulky structure such a tertiary butyl group will diffuse slower than one containg a methyl group