Accurate digital thermometer for chemicals

[Donald Qualls]

I'm aware of hand rolling drums, and in fact just ordered a drum (8x10 size Colourtronic). My counter space is very limited, however; at the very least, I'll get some casters and build a support where the drum can roll without going anywhere.

 

[Athiril]

I would use a cheap K-type thermocouple, around $20-$30. And I would calibrate it against boiling water, and known good glass thermometer, different cables/probes could give slightly different results from memory. Once calibrated though theyre great and very fast response.

 

[DREW WILEY]

It's easy to improvise things, Donald. That will at least get you started on the learning curve. RA4 is really simple in terms of the development steps. But I do recommend proportionately mixing only enough chemistry at a time for a daily session, or no more than a few days worth. And have enough volume in your water bath to keep the chem bottles (esp Dev) at reasonably precise temp, within 2F. If you don't have an adjustable heater, start out with the water jacket a little on the high side, so that the dev can reach equilibrium at the correct "drift-by" temp at actual moment of usage.

 

[Donald Qualls]

It's easy to improvise things, Donald. That will at least get you started on the learning curve. RA4 is really simple in terms of the development steps. But I do recommend proportionately mixing only enough chemistry at a time for a daily session, or no more than a few days worth. And have enough volume in your water bath to keep the chem bottles (esp Dev) at reasonably precise temp, within 2F. If you don't have an adjustable heater, start out with the water jacket a little on the high side, so that the dev can reach equilibrium at the correct "drift-by" temp at actual moment of usage.

Yep, RA-4 color dev has a pretty short life at working strength in open containers. Kodak gives it as 4 hours, though we all know they tend to be conservative for that kind of thing. In closed bottles, after mixing, it'll be good for a weekend of printing, but I wouldn't trust it the following weekend. I have a sous vide that I already use for C-41 (and Cinestill Df96). I'll probably settle on a temperature comfortably above darkroom ambient, since the chemicals can sit in bottles in the bath and the drum can float there as well (when not filled) to keep it warm. Fortunately for space limitations, the laundry tub, er, darkroom sink has a grid that drops in or lifts out, and it's plenty strong enough to support the dishpan I use for the water bath. And the "do the wrong thing" rule applies on correcting filtration -- if your print is blue, add blue to your light (subtract yellow, that is). Plus, the Kodak Viewing Filters have correction suggestions printed right on them.