Cold darkroom warm chemicals

[Nick Zentena]

If you're sitting bottles in the heated water or a second tray extra water is a positive. The greater the amount of water the steadier the temp will stay.

[craigclu]

I picked up a cheap ($7) aquarium heater at Walmart and tried it tonight. It's a 7.5W, cylinder shape that's designed for 3-5 gallon aquariums. I had some developer from a previous session in a covered tray (11X14). The heater didn't have enough energy to change the ambient temperature after about 45 minutes. I added some more developer at 1:3 with hot water to raise the tray temperature and by the time I was done printing, the tray was 3º cooler than when I started. I thought I'd share this in case someone was considering the same thing. It appears that this model doesn't have the capacity for what I was doing with it (that, or it simply wasn't working?).

[Wayne]

My 75 watt unit takes 1.5 or 2 hours to bring the 11x14 tray up to temp if it starts at about 50. But then it holds it perfectly to +/- 1 degree. I was worried it might be too powerful but its about right for my purposes. A much more powerful one might require a circulating pump. I have to turn the heat on in the darkroom a couple hours ahead of time anyway, so I just throw cold water in the tray and walk away. If I'm in a bigger hurry to start I can just use 68 degree water.

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[seadrive]

I bought a washable heating pad, with three heat settings. It's made by Cara, and cost me $25.99 at the local five and dime.

Tried it out the other night. The ambient temperature was about 50 F, so I put it on the highest setting. The starting water temp was 65, and after an hour, it had risen to 72. So I turned it down to the medium heat setting, which worked great, maintaining about 68 degrees F.

The pad is not very large, so it can only heat one tray (the developer, of course).

I'm not worried much about the stop bath, but... anyone know if fixer becomes ineffective below a certain temperature?

[Wayne]

I dont think a few degrees difference between developer and stop/fix will cause any problems, but you dont want it to be excessive. I wouldnt want my stop/fix to be in 50s, that kind of temperature shock cant be good for the emulsion.
Cooler temps may mean you need to fix longer, exactly how long would probably be a question for the maker of your fix. My fixer and stop probably stay in the mid 60's, though I havent checked. Keeping them there shouldnt be hard except in a very cold darkroom, in which case you'd probably want to get 3 heaters.

[hoginthesky]

Do you think on of these vivarium heaters for reptiles will work?? Looks absolutely perfect for my 10x8 trays (the 35"x11").

http://www.netpetshop.co.uk/p-27520-...-heat-mat.aspx

Do you think it would be good to get a thermostat or would it not be needed? It is cold in my darkroom! temperature drops to 12C (53F) and so do the chemicals...

[Wayne]

Dunno. I'm still using the same heater as before with great results.

[jnanian]

i just put warm water in my sink and warm water in a tray so the cold chems in a 2 layer water jacket
been like this for a long time, seems to work fine ...

[Mainecoonmaniac]

How about a heaters that's used for starting seedlings it's 2' wide by 9' long. It runs $65.

http://www.kalyx.com/store/proddetai.../2760/file.htm

[holmburgers]

I like the idea of a hot plate underneath the trays. The other day I saw a large (4' x 16" maybe) serving hot plate at an antique mall with a variable thermostat.

My sink is too small to use as a water bath, though if a tray gets cold I can heat it up in the sink, but it's not convenient to leave it in there.