DIY Film Processor for C41(Possibly E-6) under $100

[Deval]

I know there are a lot of people that can just get away with tuning their sink temperature to develop C41 and possibly E-6. I wanted to try to see if I could create a temperature controlled bath under $100.

I've made a "1.0 version" of a temperature controlled bath this that is capable of maintaining water bath indefinitely within 0.5-0.8 degrees Celsius and the chemical temperature within 0.1-0.3 degrees celsius(once it is at the appropriate temperature) for 20-30 minutes. It has worked very well for home C41 which has an acceptable 1degree celcius swing. I'm not sure if that would meet acceptable criteria for E-6, but I will order the Jobo E-6 Kit and try out the result after I shoot some E-6.

I will start on a version 2.0 that I know will be capable for E-6(with a 0.1C water bath), but I have to order the controller and work on the circuitry and box.

So where did I get the idea from...nothing new, nothing original - a combination of Sous Vide cooking and Homebrew Fermentation. Many hobbyists have been making cheap homemade sous-vide controllers for the last several years because the commercial options have been very expensive(>$1000). Sous Vide, for those who don't know, is a precise form of cooking which an object is cooked for an extended period of time in a plastic bath immersed in a water bath at an exact temperature(within 0.1 degrees celcius). I don't know anything about home-brew fermentation, but there are precise temperature requirements as well...Well why not use it for film

You can buy a sous-vide controller cheaper now after some kickstarter projects. A nice one is Sansaire for $199 on Sur-La-Table or from their own website. It would probably be the easiest way to get a precise temperature controlled bath. It looks very elegant as well.

When I wanted to order that one, it was sold out after their initial kickstarter round, so I wanted to make my own(and see if I could do it cheaper)

There are two popular types of temperature controllers that hobbyist use:STC-1000 and PID. I ordered the STC-1000 because its my first project and it is easier to wire. The PID is a better temperature controller, but relies on a solid state relay and a heat sink. Why is it better?
It has built in algorithms that prevent temperature overshoot by measuring the rate of temperature change which turns off the heating element earlier. The STC-1000 is simple threshold device.

Let me give you a visual for what either device looks like:
Homebrew processor by DevalJoshi, on Flickr

Film processor by DevalJoshi, on Flickr

The top picture is the temperature control unit itself. The basic STC-1000 circuit is built with a submersible temperature probe. If Temp(measured) < Temp(Set) then it gives power to the heat outlet. The heating element that I plugged into the outlet is a submersible bucket water heater which I obtained from hardwarestoreonline.com for $32(I think the brand is allied precision). The only other thing I bought was submersible aquarium water pump for $10-$15.

I set the temperature to 39 C which is the recommended for the Tetenal C41 press kit. It heats the water up to 39 and the circuit stops. In the size tub that I have, there is a 0.5 Degree over shoot in bath temperature. It does not affect the chemistry temperature in the time that it takes to develop(3:30). At 0.3C greater than the set temp, it will power the cooling outlet. Currently I haven't plugged anything into the cooling unit, but I suspect adding an air-pump that bubbles room temperature air into it would work just fine. If the temp drops below 38.7(0.3 C less than set temp), it powers on the heating element. Again, this is more than sufficient for C41. I'm not sure about E-6, but I will test it in the future.

My basic dev process is this for C41:

I set the temperature of my controlled water bath to 39. I put a jug of distilled water in the bath and let it sit for 45 minutes. Its temperature usually gets to 37.7 to 38 degrees celsius. The reason it doesn't get to 39 is that air temperature is much lower in the room.

I submerse the bottle of Developer and Blix in a separate bath of boiling water until the temperature is 39.5 degrees Celsius while I prewash the film at whatever temperature the water controlled bath at. I only measure the developer because temp is more critical. Once 39.5 I place the blix in my nice water bath, start the clock as I pour the developer in my daylight patterson tank(I use a mod 54 so I can load 6 sheets at once). The reason I raise the dev temperature by .5 is to buffer out any temperature drop while it is poured in the Tank as it travels through air at normal room temp.

I agitate as instructed on the Tetenal bath. I've tested the temperatures and they hold within 0.1-0.2 for 10 minutes with a swing of 0.3-0.5 at 30 minutes, then the blix, then the wash, then room temp stabilizer.

Ok here is a breakdown of how I made it:

STC-1000 - $16 (Amazon)
Aquarium Pump - $10-15 (Amazon)
2 large buckets(cheap, we had some at home, I assume you do as well).
Allied Precision Bucket Water Heater $32 (Hardwarestoreonine.com
1 yard black 14 or 16 guage wire $0.59 (Lowes)
1 yard white 14 or 16 guage wire $0.59 (Lowes)
Hobby Box $9 (Amazon)
Electrical Outlet with cover panel $3 (Lowes)
Electrical plug with ground $8(Lowes)
Wingnut($0.30)

Other
Tetenal C41 Kit $21 - processes 32 sheets of 4x5. Reusable.
Bottles, Thermometers
Paterson 3 tank with MOD 54

I'm not counting the others to the cost as I assume many of you have those for your BW development.

I have amazon prime, so shipping isn't an issue, I recommend it, its really worth the price.

Basic Wiring Diagram can be found on the following page:http://mostlyharmlessales.files.word...ng-diagram.jpg

It is useful to have a dremel saw or something else that can cut plastic(Soldering iron) to make it easy.

I cut the Box as such:
Film processor by DevalJoshi, on Flickr




The hole in the back is for the plug, the hole in the front is for the STC-1000 and the hole in side is for the temperature probe. The hole in the top is for the outlet.

I slide the STC-1000 in place, and hook up the temp probe. I loop the wire so that pulling won't yank the wire out.
Then I cut the wire and follow the wiring diagram.


The most important overlooked step is to separate the cold and hot out by break the tab on the side. Here is a pic:
Film processor by DevalJoshi, on Flickr

Then put the electrical outlet in place and cover with the plate. It helps to label the outlets.


I plug in the water heating element to heat. I let room temperature do the cooling. I plug in the aquarium pump separately, it keeps the water nice and even.

Here is a sample pic from my first batch of C41. No pic out of the 6 sheets had any ugly color shifts.
https://flic.kr/p/ni5Mu5

This guide will likely need to be heavily edited, and I welcome any feedback. My 2.0 will feature a PID controller which will be even more precise which I will be confident in using for E-6. If anyone tests this out with E-6 before I get to it, let me know your results. I would like to add more images but there is a forum limit of 4 per post

[goamules]

Thanks for this comprehensive guide. Maybe I'll look into doing color at home. Cheaper than autochrome, anyway.

[BetterSense]

Thermostat - type devices are all that is needed for water heating applications. Overshoot only happens if the thermal mass of the heating element is comparable to the mass of the water and/or there is no stirring. ..and if there is no stirring then PID isn't going to give good temp control anyway. I have made many water baths for brewing, photography, and industry and used on/off thermostats for most of them. I have an STC1000 driving my kegerator now.

[jbenedict]

Thanks for putting this together. You did my research for me!


I actually have a Jobo but don't really have a place to operate it. I have the World's Largest Changing Bag from a one-hour printer. L4 x W2 x H2. I have no problem loading but having a smaller setup would be nice for doing medium format and 4x5 in a tank.

[Tin Can]

Ideas like this will get me doing color pretty soon...

Thanks!

[peter k.]

Ok, have a question.. I live where it gets warm in the summer, you mention..

Currently I haven't plugged anything into the cooling unit, but I suspect adding an air-pump that bubbles room temperature air into it would work just fine.

I take it you haven't tested this part of it thoroughly yet?
It would be a concern of mine because of where I live, it gets warm in summer, and I don't think that room temperature would cool it down enough.

[Deval]

Thermostat - type devices are all that is needed for water heating applications. Overshoot only happens if the thermal mass of the heating element is comparable to the mass of the water and/or there is no stirring. ..and if there is no stirring then PID isn't going to give good temp control anyway. I have made many water baths for brewing, photography, and industry and used on/off thermostats for most of them. I have an STC1000 driving my kegerator now.

I had a feeling the overshoot had to do with not having a big enough circulator and bucket. Thanks I will take that into account when I try e6

[WayneStevenson]

I've just been using my sink and faucet for a water bath for a few years doing my colour processing.

I have a Jobo ATL but it's a pain, and needs to be hooked up to both hot and cold water to operate. So I never use it.

I made myself a dual PID controller setup. I have posted the details here before possibly. But at any rate, you may want to have a look at my setup.

https://www.flickr.com/groups/ishoot...7632985514766/