C-41 Temperature control unit - found this on Kickstarter

Aside from the price (currently $145, shipped), what do you think of repurposing this sous vide cooking device for the darkroom?

Its chief advantage is precision temperature control and water circulation, and it needs only 2.5" - 7.25" of water depth.

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Way more difficult than it needs to be. What do you tell it to cook, chicken? Fish? All the temps that sous vide run at are much higher (like 55-80C) than needed for developing film. C41 and E6 develop right in the never-keep-food-at-these-temperatures bacterial-danger-zone so if the device is any good, it will prevent you from selecting 38C.

Just buy a $20 PID controller with thermocouple off eBay and wire it up to a water-boiler element. Stick an aquarium pump in too (makes the heating uniform) if you're feeling fancy. Or you can wire up a slow cooker/crockpot to the PID controller and use the slow cooker as your temp-control bath. Try to use one with a low thermal mass (aluminium liner, no ceramic crock) though, because that may cause PID instability and/or inability to respond to temperature changes in a speedy manner.

Be that as it may, the stated range is
Temperature Range: 77°F to 210°F ± 0.01°F / 25°C to 99°C ± 0.01°C

there was an article on MAKE for the same thing

http://makezine.com/2011/02/17/75-sous-vide-immersion-cooker/

I've put together 2 of them from ebay parts for way less than what the article states by the way

Ok, my original question was "aside from the price"...

I built myself my own. Mine has dual PIDs for two baths (say if I wanted a C-41 and a warm B&W path for push processing).

But this one is slick looking, compact, and I would gladly trade in mine if the price were under $80, and it had a PID controller (it may?).

Cut around $200, there's no way I would justify the novelty of it.

Sheesh, I just use a plastic cooler my late father had. I fill it with hot tap water, add my bottles of chemicals, and about twenty minutes later I'm ready to go. If the developer temp is a bit too high, then I leave it out of the cooler while I do my presoak.

Paul Cunningham said:

Be that as it may, the stated range is
Temperature Range: 77°F to 210°F ± 0.01°F / 25°C to 99°C ± 0.01°C

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I doubt the specs is accurate. To get a temperature control/indicator to that kind of accuracy and temperature range is not cheap. Not for $140.

You can get a PID module off evilbay for 25 bucks and it comes with temperature sensor and SS relay. Buy a water heating spiral or an aquarium heater + a circulating pump for some 10-15 bucks to the set and you are good to go. Or do the cheap and cheerful version - take a cheap cooler and fill it with warm water. I get my ECN2 chemicals up to required temperature in 10 minutes with the hot water coming from the tap at 45 degrees centigrade; required temperature is 41,5C so I can let it cool a bit. So far no problems. Churning out 200 bucks for something you don't need at all or can assemble from crap off evilbay is silly.

I think it's an excellent idea. The only question mark would be how efficiently it circulates the water in a tub rather than cooking vessel.

But it looks convenient and if it saved you a lot of fiddling with water temperatures, then the price is not really that high.

Terry Christian said:

Sheesh, I just use a plastic cooler my late father had. I fill it with hot tap water, add my bottles of chemicals, and about twenty minutes later I'm ready to go. If the developer temp is a bit too high, then I leave it out of the cooler while I do my presoak.

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Thanks for saying it. With all this talk of slow cookers and fish tanks, it's no wonder people are put off by C-41. It just doesn't require that much technology to maintain a liquid at 100F for three minutes. For my own part, I fill a Playmate cooler with hot water at 118F to just below the level of developer in my Paterson tank. The developer goes in at 101F and comes out at 99F. (I check it every time.)

bvy, that's the exact same cooler I use.

To be honest, all that temperature control and heater nonsense put me off from color developing for quite a bit. But it really is not any harder than BW development, except from maybe stand development. In some occasions it might be even easier since the process is quite straightforward and standardized, whereas there is constantly a Holy War going on about developer/film combinations in the B&W world.

For C-41 for about 50 rolls so far, I've been using Unicolor 1-liter powder kits. I use a small 6-pack cooler to pre-heat the empty tank/reels/film. To get the tank/reels/film to the 102F developer temperature, I add 104-105F water to the cooler and measure the cooler water temperature with a digital thermometer with a wire probe (Extech TM20) calibrated to a Paterson Color Thermometer. I add small amounts of hot water to the cooler as the tank heats up from room temperature and the cooler water cools down. When the cooler water temperature stays constant at the developing temperature I know the tank/reels/film are in equilibrium at the right temperature. This process takes about a half hour. In the meantime I measure out and filter the chemicals.

Then bring the pre-soak water and chemicals to the right temperature and maintain the cooler water temperature with small amounts of hot water. Good temperature control is required only for the water pre-soak and developer steps as blix can be done +/- a few degrees, but it's easy enough to maintain the same temperature for the blix stage as well (and stabilizer is at room temperature).

Results have been excellent, producing negatives with good density and true colors that make beautiful prints.

I also use a similar, simple way to do temperature control when I make RA-4 prints, again with excellent results.

Excellent method, but it does highlight the time and effort which goes into keeping 100F manually.

I use a double tub system where I put a smaller tub with 100F water into a larger tub with 104F water.

The larger tub compensates for the heat loss in the smaller tub. Thereby the smaller tub stays at a constant 100F for 30 to 40 minutes depending on room temperature. This is enough to pre-heat everything and develop the film.

But if could just put a pod that keeps the water at 100F indefinetely, I would.

I'd say, if you have the money and it works for you, then do it!

Terry Christian said:

Sheesh, I just use a plastic cooler my late father had. I fill it with hot tap water, add my bottles of chemicals, and about twenty minutes later I'm ready to go. If the developer temp is a bit too high, then I leave it out of the cooler while I do my presoak.

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Sheesh. I just use my steel kitchen sink. Don't worry about cooler. And temperature control isn't that critical. Use my faucet to set it. I do that when I'm only processing a couple rolls.

But developing ten tanks of film gets tiresome when I'm having to wait for my temperature to build up. I eventually stuck a couple heaters and pumps in.

And last year, I built the PID controller setup. Which I still use in my sink. But it maintains temperature far better than the thermostats on the submersible heaters.