MacGyvering a tempering bath for color development

bobwysiwyg · Apr 9, 2013

Lamar said:
I've always used $22 GE roaster purchased at Walmart. I've never had a problem maintaining temp within tolerance for the whole development time once temp is stabilized.

View attachment 66986

So the low setting (presumably) holds the temp low enough for the color chemicals? I tested our slow cooker, a different make, and the lowest, stablized temperature was around 120F.

Chan Tran · Apr 9, 2013

I use a roaster oven. Turn the temperature control on the oven to max so it's always on. Connect a good PID temperature controller to the AC plug and put a thermocouple in the water. It works great.

bobwysiwyg · Apr 9, 2013

Chan Tran said:
I use a roaster oven. Turn the temperature control on the oven to max so it's always on. Connect a good PID temperature controller to the AC plug and put a thermocouple in the water. It works great.

Sounds like the ticket. What PID controller are you using if you don't mind my asking.

Lamar · Apr 9, 2013

Yes, it goes low. I've added marks on the controller to get me in the ball park then it's just a mater of dialing it in. I start by filling it with tap water a little above the required temperature and by the time the fill is complete it is just about right. Ambient temp makes a difference, if it's winter and the house is cooler my thermostat setting is usually a little higher than my mark. It isn't a walk away type setup though; if you walk away for a half hour you may find your temperature has change by several degrees. I Initially check every 5 minutes or so and make fine adjustments to the controller as necessary. After a few cycles of checking and adjusting it will hold the temperature for the entire development process.

bobwysiwyg said:
So the low setting (presumably) holds the temp low enough for the color chemicals? I tested our slow cooker, a different make, and the lowest, stabilized temperature was around 120F.

Chan Tran · Apr 9, 2013

bobwysiwyg said:
Sounds like the ticket. What PID controller are you using if you don't mind my asking.

I use this controller
http://www.newark.com/omron-industr...ontroller-temp-1-16-din-100-240vac/dp/58T9504

with this solid state relay so I can have it switches on and off very rapidly

http://www.newark.com/crydom/d2425/...rydom Top Seller&MER=PSPSO_S_C_Crydom_93K7541

I use them only because I have them on hand. A great number of others will work fine. Pricing about the same for simple one. Or you can buy the one that the OP used.

WayneStevenson · Apr 14, 2013

Finished housing most of mine. It's working great as a tempering bath. I like to let it run in the background. I feel pretty satisfied with it. Hah. Waiting on some more parts for it though, and have a lot of testing to do. I especially want independant power switches for the timer relay (to turn the air pump agitation off) and the two PID controllers as I don't intend to run them both always. Was going to also house the circulation pump inside but I'm thinking it might be a bad idea to have the pump right there. I have two outlets on the outside that I can run pumps with. And the bottom two outlets are isolated from each-other and PID controlled for the heating elements. Since the origional elements aren't a good idea at this point, I don't have a need to house it within the case.

chuck94022 · Apr 16, 2013

Wow, step away for a few weeks, and I see a whole community is forming! Haha!

There are certainly lots of ways to skin this cat. Maintaining temps isn't necessarily rocket science, but it's a lot of fun when you decide to throw a rocket at it! Wayne, I'll be curious to know if the aquarium heaters do it for you. I feel they are sort of weak, and are probably better at maintaining than at initial ramp of the temps. Also, if your container isn't insulated, they might have a lot of work just dealing with the dissipating heat as the surrounding air tries to cool the container.

If you have a big tank, I think your original big heater would be just the ticket. But just make sure you have a strong circulation pump to keep the hot water moving off the heater. If the SSR can drive the heater (big question, make sure it can handle the load), it should cycle rapidly enough that the heater will never get very hot except during the initial heating. Mine cycles at a blindingly fast rate.

My PID controller has the ability to set temperature alarms. You might check that, if you fear the thing getting stuck on. Or, get a separate electronic probe with an alarm if you really want assurance. So far I'm not feeling the need, but I can imagine if you're D&D with big 8x10 sheets you might want some extreme assurance!

I love the simple roaster idea, but for the $ spent, I'm happy with my way-too-accurate bath...

Chan Tran · Apr 16, 2013

But now Chuck, how do we keep the print drum inside the tempering bath while processing like the Jobo?

WayneStevenson · Apr 16, 2013

chuck94022 said:
Maintaining temps isn't necessarily rocket science, but it's a lot of fun when you decide to throw a rocket at it! Wayne, I'll be curious to know if the aquarium heaters do it for you.

IT IS so much fun. Heh.

I used them before in my kitchen sink for my tempering bath before. They're doing it great. Relatively. I have two 50W heaters. In the small tanks they were working beautifully. Two of them in a larger tank and they work beautifully.

Using them separately with larger tanks, I'm maintaining a stable temperature but it's having trouble auto-tuning. Sometimes it does, sometimes it doesn't.

They're in identical setups so when one did tune, I carried over the settings to the other one and it's maintaining no problem.

And yes, initial heatup on a large volume is going to take some time. Taking about 15min. right now. Scale it up using these heaters, and I'm probably looking at an hour long heat-up.

I have three heaters coming in to try out. Three 200w. Including a stainless steel one. Though I think by accident, I ordered a 220V so it's not going to be any better than the 50Ws I am thinking.

But I'm probably just going to go and find me a 1000W or 1500W heating element and be done with it. Which was the way I was going initially, but forgot. And ordered more aquarium heaters............

WayneStevenson · Apr 16, 2013

Oh, and I'll add that the thermostat (or capability) of my particular heaters are maxing out at 42C regardless of how far I turn it around. One seems to actually stop, the other goes round and round. But the temperature doesn't climb any higher than 42C.

chuck94022 · Apr 18, 2013

Chan Tran said:
But now Chuck, how do we keep the print drum inside the tempering bath while processing like the Jobo?

Ha, Chan Tran, for that you need a Jobo! Or a Sidekick.

Seriously though, I think your best bet is engineering something that keeps trays at temp for printing. Drums add all kinds of other variables, like rotation control, for example. Going there, I'd just buy a Jobo (which I used to own).

WayneStevenson · May 31, 2013

So for those of you wanting to use aquarium heaters to temper your water / chemistry, I have come across several different types that require different methods to adjust beyond their "maximum" temperature.

These heaters are all goverened by a thermostat that prevents them from heating water past a safe temperature for your fish. Which is always around 32C.

But the thermostat is capable of going above, or when using a PID controlled thermostat, disabled altogether.

In each case, the thermostat appears to be set with a screw on the end of the heater where the cord comes in. Turn one way and a plastic rod screws in to decrease the max temperature, screw the other way and the rod is pullup in the opposite direction.

They all use some sort of plastic limiter tab that prevents the knob from turning too much either way.

Sometimes they are built into the knob. So you remove the screw from inside the knob so it can be pulled off when it can't turn any more. And brought to the lowest temperature indicator, and you do that over and over again until you can't move it any more.

Others use a pointer on the knob that hits a plastic block. You can cut the block off or the pointer so there is nothing to stop it from turning all the way around.

Two other methods had internal blocks. One required pulling up on the knob once it reached the maximum and wiggle it to get past the block.

The other required the removal of the insides to cut out the plastic block. On that particular one, the insides are not epoxied or anything. Just set into a rubber bung to seal everything. Carefull pulling on the cord and knob slowly eased the bung out.

They're in a glass tube so don't put a knife or anything in it to pry it out or you'll just end up breaking the glass. Small $10 loss as that's all these things cost on eBay. But you can often be waiting for up to a month for them to come across on the slow boat.

madgardener · Jun 1, 2013

The best aquarium heater I've found for this purpose is the one Walmart sells. The Tetra 30-60 aquarium heater. To adjust it, simply pull the knob off, re-position it, and keep cranking it to raise the temperature, I've gotten it to hold the temp at 101.8(F). It cost $15.

When my finances improve, I want to find a PID controller with a controlled outlet and let that control the temperature instead of the internal heater thermostat.

WayneStevenson · Jun 3, 2013

The PID controller is definately worth it.

And really, if you're DIYing, isn't that expensive.

My breakdown was this:

PID controller was $13, power switches and socket go for $4, thermocouple is $4, $2 for the plastic Dollarama bucket, $10 (5 each) for DC pumps, $3.50 power cord, $7 heater, $14 for GFCI recepticle. Plus some wire, solder (not necessarily needed), morettes (again, not needed), electrical tape, etc. Everything but the GFCI, wires, electrical tape, etc. were ordered off of eBay with free shipping.

I also purchased relays, but ended up killing one and went without as the PID controller already has.

Shootar401 · Jun 4, 2013

I use a microprocessor controlled water bath I bought off ebay for $20. the tank it roughly 20" x 20" and 6" deep. I can set it for 105 degrees for E6 and it holds that temp within a quarter of a degree.

I tried the DIY/cheap way out and it was actually more expensive to go that route with buying all the parts and the time involved.

Chan Tran · Jun 4, 2013

chuck94022 said:
Ha, Chan Tran, for that you need a Jobo! Or a Sidekick.

Seriously though, I think your best bet is engineering something that keeps trays at temp for printing. Drums add all kinds of other variables, like rotation control, for example. Going there, I'd just buy a Jobo (which I used to own).

but a Jobo is very expensive.

AnselAdamsX · Jun 4, 2013

FWIW there is a PID library for arduino http://playground.arduino.cc/Code/PIDLibrary

chuck94022 · Jun 5, 2013

Chan Tran said:
but a Jobo is very expensive.

Well, Chan, if you are serious about using a roller drum, I would suggest that you build the tank to the dimensions you require, then build a platform so that the rollers sit at a depth sufficient to roll the drum through the hot water, just as a Jobo's bath does. If you have seen/used a Jobo, you know that the drum isn't fully immersed in the water. Instead, the machine holds one side of it in the water, and rolls it in this little hot puddle. You could create yourself a little structure like this yourself, suspended above or within a water tank. I'm not doing rotational processing, so I've left this as an exercise for other creative users.

WayneStevenson · Jun 6, 2013

"I tried the DIY/cheap way out and it was actually more expensive to go that route with buying all the parts and the time involved. "

Absolutely. But sooo much fun.

"Well, Chan, if you are serious about using a roller drum..........."

That is the route that I am taking now. I've just done some initial testing with SS reels and tanks on a Unicolor drum roller. Results are acceptable as far as even development. I have to fine-tune rotation speed mind you, and / or development time.

To head off the "get a Jobo" comments, I do have an ATL. It just isn't cut out for EFFECIENT volume processing. I have at least 10 SS tanks that I use when I do my processing marathons.

I plan to rig up a couple rollers and DC motors into a wide wallpaper trough, using my "maguyvered" tempering bath controller to keep my chemistry and tank at process temperature.

I have way too much time on my hands. Heh.

nworth · Jun 7, 2013

A fairly cheap alternative is a fish aquarium. You can get recirculating water filter/heaters for them that can be cranked up to the proper temperature. Usually they are a bit too deep, so you have to find some sort of a filler or platform to put the bottles on.

chuck94022 · Jun 8, 2013

nworth said:
A fairly cheap alternative is a fish aquarium. You can get recirculating water filter/heaters for them that can be cranked up to the proper temperature. Usually they are a bit too deep, so you have to find some sort of a filler or platform to put the bottles on.

I'd wager that my plastic tub was a lot cheaper (and lighter) and not nearly as deep as a fish aquarium! And the styrofoam container I used as an outer insulator was free.

In my case, the water pump was for either a large aquarium or a water fountain. The aquarium heaters have the issues discussed (and worked around) above. Personally, I think if you use a PID (which is accurate to .1 degree C) you're better off using a stronger heating element. But that's a personal preference. I have no idea how accurate the controller is in an aquarium heater, but I doubt it is as accurate as a PID controller. But it is probably good enough.

nworth · Jun 9, 2013

chuck94022 said:
I'd wager that my plastic tub was a lot cheaper (and lighter) and not nearly as deep as a fish aquarium! And the styrofoam container I used as an outer insulator was free.

In my case, the water pump was for either a large aquarium or a water fountain. The aquarium heaters have the issues discussed (and worked around) above. Personally, I think if you use a PID (which is accurate to .1 degree C) you're better off using a stronger heating element. But that's a personal preference. I have no idea how accurate the controller is in an aquarium heater, but I doubt it is as accurate as a PID controller. But it is probably good enough.

You're probably right. I've used a variation of this myself. The tub I had had a motor to keep the water circulating (avoiding hot and cold spots), and I was able to use a simple, cheap immersible fish tank heater to control the temperature. Proportional controllers are nice, but fairly expensive. Adjustment of things like fish tank heaters can be tedious, but once adjusted they stay set quite well, and I've found them to be quite adequate.

Chan Tran · Jun 10, 2013

Good idea. I am going to get a Jobo drum and then somehow putting 2 roller rods under the water. The rods need not be driven just free rotating. Putting the drum on top of them and then a motor driven rubber roller pushing down on the drum would drive it.

madgardener · Jun 12, 2013

I just finished my first 2 rolls of C-41 in my home made setup. The 200 watt heater seems to be undersized for my setup, it seems that there will be a 300 watt sometime in the future. For right now though, it works ok. Without anything in the container, I can get the water up to 102(F), but as soon as I put my chems in to warm up, the temp dropped 6 degrees and stayed there. So I put the chems in the bathroom sink filled with very hot water to warm them up. Once warm and put in the bath, they held just fine and the heater was able to keep the temperature stable during developing.

As soon as the negs are dry, I'll scan them and post the link for some critiques.

clayne · Jun 12, 2013

This is what I use:

1. Blueline 250w titanium heater element (http://www.bluelineaquatics.com/products/heaters/).
2. Blueline temperature controller (http://www.bluelineaquatics.com/products/heaters/).
3. Koralia Pico Evolution Evo-Mag 300 GPH Nano Aquarium Pump (bunch of ebay sources).
4. Coleman 28qt cooler I picked up at Bevmo for beer during get-togethers.
5. 3 1L accordion containers for FD, CD, BX or 2 1L accordion containers for CD, BX (Freestyle).
6. A couple small bricks I picked up from Home Depot to keep the containers from floating around.

I bought the heater+controller for 95$ as a combo deal on eBay, the pump for 20$, and the Coleman for 20-30$ but it's cost was of course amortized against it's intended use: beer.

The reason I specifically went for a titanium element and an external controller rather than an all in one cheapo-unit is that the former usually go beyond 100F (even if unsafe for fish) just by design. One is able to set temps of up to 110F if I remember correctly. The controller itself uses an external probe and is basically a fancy relay for the heater itself. The pump you just plug in. I fill the Coleman up with 90F+ water from the sink, turn the controller on to 37-38C, place my 1L accordion containers containing FD, CD, BX (E-6) or CD, BX (C-41) and let it stabilize for 20-30 minutes. I don't bother heating the stab for either processes. The bricks I just submerge and wedge against the containers to stop them from floating or moving around.

Heating element, pump, probe in water:

External controller:

My coveted mercury-based Kodak Process Thermometer:

2-stage C-41 setup:

First roll of Astia (E-6) I developed with the setup:

Another roll of Astia (this one in Polyester fold-flaps, so there's reflection glare):

Nothing beat the moment I pulled the slides out of the tank and saw such jeweled color against the light. It was better than the first time developing black and white, honestly. Recently I picked up a Phototherm bath but haven't used it for any development other than testing that it worked properly. It's cost was around the same aggregate cost for the ghetto-route, but I can tell the temperature stabilization is more precise and the built in pump is nice. It's entirely self-contained and well-designed but I don't think it'll make a difference in the final product (just less hassle).

MacGyvering a tempering bath for color development

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