View Full Version : print chemical temperature

brian steinberger
13-Mar-2005, 21:56
my darkroom is in my basement and the temperature is 60 degrees right now, during the fall and winter months. is it ok to develop prints (with dektol) at 60 degrees or does atleast the developer need to be warmed up to 68 degrees? what about the stop and fix?

Mike Davis
13-Mar-2005, 23:13

I use a small electric heater in the winter to warm the room for an hour or so, and then put dev, fix, stop, and permawash in a running water bath at ~70-72 degrees. It may be overkill, but I do it anyway.

The summer is my problem, the heat in my darkroom is often over 80 degrees even over 85. So, I do things like print at night. Of course I do dev by inspection for prints when its hot and I use a water bath to chill the chemicals before I begin. I hope to get AC in there before I have to deal with another summer.

Ben Calwell
14-Mar-2005, 06:04
My darkroom is in my basement, too. I keep one of those oil-filled electric radiators in it, and I place it under my sink. The heat gently radiates up through the sink keeping the trays at an almost perfect temperature.

Brian Ellis
14-Mar-2005, 06:18
The chemists among us could probably give a better answer but in general the temperature of the developer for prints isn't critical. There must be some low and high temperature point at which some kind of bad chemistry thing starts to happen but I think temperatures in the 60 - 80 range should be o.k. The main difference is that cooler temperatures will result in longer times for the developer.

I'd guess that the fix temperature is more important than the developer. With developer you can see, more or less, what is happening and leave the print in for as long as it takes. With fix you can't see anything happening but temperature presumably afects the time in the fix in the same way it does the developer (i.e. cool temperatures require longer times and vice versa). But that's just speculation on my part. The only thing I know from experience is that developer temperatures within reason aren't critical.

Gem Singer
14-Mar-2005, 06:57
Hi Brian (not Brian Ellis),

At 60 degrees F, my body and brain don't function at 100%. Get yourself a small space heater and be comfortable while working in your darkroom. It's difficult enough to work in the dark. Why make it more difficult with the need to wear long underwear, a heavy sweater, mittens, and ear muffs? (that's my thought before having my first cup of coffee on this chilly morning).

After thought. At that temperature, photo chemicals work so slowly that you'll probably freeze your backside before the image comes up in the developer tray. Good luck on reaching the D-Max of your printing paper.

J.L. Kennedy
14-Mar-2005, 09:45
Eugene- I've heard that 60 degrees F is the optimal temperature for brain function. I don't know about body function, however!

Nick Morris
14-Mar-2005, 10:45
Hello. I believe that temperature can effect tonality (warmer/cooler) and contrast, but I might be wrong about that. It would increase the time required for full development, and that might open up other problems. I usually develop prints in Dektol at 70 degrees. To warm chemicals, I put real hot water in zip lock bags ( about 110 degrees) and watch the temp.

14-Mar-2005, 11:25
temperature for pyro developers is critical if you want consistent results. Not everyone developes by inspection where temperature may not matter as much because you develope for however long it takes.

Bruce Watson
14-Mar-2005, 15:28
Most normal paper developers contain two or more development agents. For example, Dektol is mostly metol and hydroquinone IIRC (and it's been a loooong time, so please correct me). Turns out that the component developing agents have different activities at different tempertures. IOW, if you expose two sheets of paper identically, and develop one at 60F, and the other at 68F (compensating development time to get the same densities), one, the colder one I think, will be more contrasty then the other. That's because the lower temperature "unbalances" the Dektol.

This is why people preach about making your processing consistent. It really doesn't matter too much what temperature you use, but you should always use that same temperature.... or you should resign yourself to unpredictable, and unrepeatable, results. Clearly, YMMV.

14-Mar-2005, 18:28
I posted on this topic here: http://www.largeformatphotography.info/lfforum/topic/499927.html

Also, I'd say that 60 degrees is close the minimum temperature at which dektol will perform anything like dektol. Of its two devoloping agents, one of them (hydroquinone) is much more temperature sensitive than the other, and is almost innert as the temps dip into the 50s.

neil poulsen
14-Mar-2005, 18:48
Ansel Adams goes into length on this topic for Dektol in his book, "The Print". The hydroquinone developing agent loses it's effect at around 55 deg.F, while the metol tends to be more linear. So at lower temperatures, prints can go soft. Adams recommended 68 deg.F. At 75 deg.F, the activity of the hydroquinone increases disproportionately, so that's a bit warm.