Time and Temperature Adjustments - Curious

I am curious as to some of your opinions and experience with time and temperature adjustments...

What are your experiences with changes from varying time due to temperature - any noticeable effects?

I searched and didn't locate much...

Personally, I adjust all temperatures (except wash) to 68 degrees prior to developing sheet films....but with roll films I get lazy and use the time-temperature charts - adjusting development time according to temperature of chemicals...which actually vary from day to day - on average 72 to 76 degrees...

Are consistent results really possible from adjusting time with temperature...in your experience?

Thanks,
Dan

For film development, I start by setting the temperature of my chemicals as close to 70F as possible. If the temperature varies a few degrees above or below 70F during the processing procedure, it doesn't seem to have a noticeable effect.

After the film is fixed, the temperature of the running wash water out of the tap usually varies as much as 5-10 degrees with no ill effect.

I develop all of my film (Ilford HP-5+) in Pyrocat-HD for 9.5 minutes, whether it is 120 roll film, 4x5, or 5x7 sheet film, using minimal agitation (Constant agitation for the first 30 seconds.Then agitate for 15 seconds at two minute intervals).

This gives me an ideal negative for scanning.

From my experience, I have found that the agitation pattern has a much greater effect on the contrast, sharpness(accutance), and granularity of the film than the time and temperature variation.

Adjusting with the standard time:temp table works fine for me. Most of the time I end up using a temp around 22C which is what comes out of my tap.

Quote:

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Originally Posted by DanK

What are your experiences with changes from varying time due to temperature - any noticeable effects?

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Depends on the developer. Developers with more than one developing agent might give different results at different temperatures. It's been years, but I seem to recall that Metol and Hydroquinone have different activities for different temperatures. That is, at lower temperatures you get more activity from the hydroquinone, and at higher temps. more from the metol. Or the other way around; IDR.

From a practical sense, what this means is that all things being equal (that is, you've adjusted development time per your time/temp chart), you'll get somewhat more contrast than you expected from the lower temperature, and somewhat less than you expected from the higher temps. From an MQ developer that is. Other developers will of course have somewhat different characteristics.

This is one reason manufacturers give you a preferred temp. for developing. As you stray from that temp. you stray from optimum results.

Temperature also effects the rate of emulsion swell, developer uptake by the emulsion, diffusion of the various chems. in and out of the emulsion, etc. It all plays a non-negligible part.

Does it really matter to you? Maybe, maybe not. Usually these effects are small enough that they are difficult to discern even if you are looking for them. But not always.

It really comes down to how much you want to be in control of your process. If you want repeatable results, you have to have a repeatable process. But I suspect you already knew that.

My water comes from the pipe at 80F in the summer. I tried various methods of lowering the developer temperature, but found that with some of the old style European films, the differences in solution temperatures caused physical problems in the negatives. I learned to adjust my times to the temperature, so that I could have all of my solutions, including wash water, the same. It seems to be the difference in temperatures between solutions that makes a difference.
After working out my temperature charts, I get repeatable results.
juan

For sheet film, I use the Zone VI compensating timer. I never use a thermometer, and it has worked well for Kodak and Ilford film in a variety of developers with working temperatures that are in the range of 65 to 80. For roll film I use an accurate thermometer and standard tables to make adjustments. (Clayton had a nice one they put out.)

Thanks for your responses....

Gem...I agree completely with results from agitation causing significant changes...I fought with contrast for a good amount of time....finally realizing excess agitation was the cause...

Brian - Thanks, I'm lucky enough to have low water temps for around 6 months, which I can adjust with a mixer...summer just doesn't give me cool enough tap...so I rely on icy-cools during the summer months....

Bruce - Thanks, I never considered the fact that the emulsion would react differently to a specific developer at different temps...I was thinking simply a 'straight line' effect acroos the spectrum....appreciate your response...

John - I've been experimenting with older emulsions that aren't fond of higher temps...summer temps sure make temp control an issue....thanks...

Kevin - I've never used a compensating timer...sticking strictly with the charts...thanks

Dan