Theory for temperature compensation

S

sidxms

Messages
991
Edit My Images
Yes
AFAIK,

The reactions for BW chemistry aren't organic. However, temperature compensation charts indicate that even a 6C variance in temperature should halve/double development times.

the overall change in kinetics of the molecules is negligiable for a 6C temp difference at room temperature.

I know that a 6C rise in body temp will kill you for example but I'm not convinced that it would be the case for standard chemistry

Anyone have any theory on this.

From personal experience compensation for temp for 3-5C difference gives me worse results than just assuming its 20C.
 
sidxms said:
Anyone have any theory on this.
Click to expand...

My theory is that the manufacturer has done the experimentation so I don't have to. Why would they give information which is not correct?

I have had no problems using temperature/time compensation with Ilford developer.


Steve.
 
Steve Smith said:
My theory is that the manufacturer has done the experimentation so I don't have to. Why would they give information which is not correct?

I have had no problems using temperature/time compensation with Ilford developer.


Steve.
Click to expand...

Well obviously they've optimised it for a certain setup but I'm not entirely convinced about effects of large deviations from that at small temp differences.
 
I dare say one degree or so may not make any significant difference, but 6 degrees above 20C without compensating would be a little risky in my view. I've used a variety of Ilford developers over the years, but I have also used Kodak and Paterson too many years back and always followed their recommended times and have never had any problems.

I'm not sure why you've had worse results when you've been compensating for temperature variations, but I personally always try and keep it at 20C anyway.
 
I'm wondering why you would be 6 degrees off the desired 20c? It's a lot easier to get your chemistry to the correct temperature, rather than taking the compensatory route. Even in a cold room it's still possible to get your chemicals to the correct temperature, or vice versa in a hot room. It's quite possible I'm missing the point here, so apologies chaps.

Nigel.
 
Steve Smith said:
So what do you mean by worse results?


Steve.
Click to expand...

Well by looking with the naked eye, the shorter development times gave an underexposed look when finished. They were very grainy when scanned in as well.

Comparatively, I did normal development time with the solution at 23-24C and got subjectively speaking better looking negs and scans so I dunno tbh...

Also I would obviously use 20C if possible but if the tap water is above that then theres no way to cool it down in the darkroom :(

sid
 
sidxms said:
Also I would obviously use 20C if possible but if the tap water is above that then theres no way to cool it down in the darkroom :(

sid
Click to expand...

Sid, Whereas you would stand your chemicals in warm water to raise the temperature, you conversely stand your chemicals in ice. A couple trays of ice cubes from the fridge will do the job ;)

Nigel.
 
You must log in or register to reply here.
Back
Top