DIY Jobo-style processor?

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

Right now I just use a Patterson tank and reels to develop my B&W film, but I'd like to get back into developing color again, especially slides because it's become so inconvenient and expensive to have them developed. Way back in the 80s I used to develop my own slides, and it was a real hassle trying to keep my bath at +/- 1/2 degree F, so it's gotten me to wonder just how difficult it would be to build a tank that would hold a bath at an exact temperature. I'm thinking it would actually be pretty easy.

In my case, I wouldn't need the rollers that some Jobo systems have or the lifts or whatever other gizmos they contain -- just room enough for the bottled chems to be put in the bath and to roll around the developing tank manually. Or maybe I could just agitate it every 30 seconds or so the way I do it with my B&W films. That would still work as well I'm thinking. I also have a couple of the tanks with the spinners for agitation. They seem to work fin for 35mm, but I've gotten streaks with my 120 when using them, so I don't use them anymore -- at least for 120.

Ever seen a heater used in reptile terrariums? It's just a large flat plastic pad with a heating element inside and with an adhesive side so it can be pasted onto the terrarium tank's bottom surface. It plugs into a wall socket and heats up to raise the temperature far enough inside the terrarium so the reptiles are comfortable -- probably with an air temperature around 105F to 110F. This is most likely too warm for color chems, but one can rig a dimmer switch up to an outlet box to control temperature.

So just wondering if anyone else here has had thoughts along these lines and what, if anything, you might have come up with?

Attila · Expire: 2025-11-18

I did develop myself slides 25 years ago I did put simple developer tank into bathroom and I did put fine temperature water to bathtub. I don't remember for difficulties, lot's of water did cool down slowly I think safe enough to develop slides.

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

Back in the 80s when I did it, I used my bathroom sink as the developer bath and used ice cubes to fine tune the temperature. The temp stayed relatively stable once I got it where I wanted it, but I can recall having to fiddle with things for quite a while before getting it to settle at the right temperature. This is what I'm trying to avoid with a temperature-controlled bath.

marty · Joined: 09 Apr 2009 Posts: 767 Location: Italy

That would be an interesting project. At the moment I'm developing C-41 keeping the tank (the type with the spinning rod) in a water bath within a plastic tub. I start a couple of degrees above 38°C, I'm able to maintain the temp correct during the development then starts to drop but it's not critical at that point. I warm up the chemicals at 38°C before to start with the same water bath. The negs look fine to me, I'm able to make RA-4 prints with reasonable consistency. I've done E-6 too with the same method, it's a bit trickier here because the temp has to stay at 38°C during the two development phases. I kept a thermometer in the tub and added hot water from the tap when the temperature was dropping. The slides look fine to me. I'm not pretending is a perfect method but works for me. I have not great numbers to process and usually I'm not in a hurry. Failing that I think it's going to become unpractical. And of course I'm not pro and even if I screw something nobody's gonna lose anything (not yet happened so far).
That's my experience for what's worth. Now a link that may be interesting, looks simple enough and inexpensive too: http://www.dunnamphoto.com/tempering_tray.htm
And another one probably useful to a more advanced kind of hobbyst:
http://ludens.cl/photo/processor/processor.html

Cheers, M.

cooltouch · Joined: 15 Jan 2009 Posts: 9096 Location: Houston, Texas

Thanks for the links, Marty. More to think about.