Heating of H20 for color film processing

[DanielStone]

hi all, again...

I've decided that I want to start developing my own c-41/e6 at home from now on, rather that using the facilities at my local photo program. This is where I will continue to use the darkroom(not enough space in my house to hold one of my own, i'm the eldest of 4 kids). But I've noticed that there isn't much consistency of the water through the taps at the center when developing. They have jobo's but I have had no luck with them, and being that they are quite well used, the heaters in the tanks don't work as effectively or as precisely as they should.

And now that I'm much more serious about the quality of my work, versus a year ago when I started, I need a heater for my water bucket.

I've heard and read many accounts from people who have used aquarium heaters to much success, but after making a trip to 3 of my local aquarium supplies, they have all said "why do you want to fry your fish in 100 degree water?"

Basic problem I want to solve: Does anyone know of a self-controllable heater that won't break the bank?

 

[martyryan]

Your question got me to looking, the best that I can find would be this http://www.jeffersequine.com/ssc/product.asp?CID=1&pf_id=16047 .

Marty

 

[Nick Zentena]

http://www.wonbrothers.com/product/heater/ICHEATER.htm

Thats the brand I got. It's adjustable so it'll run hotter then the dial reads. So even if it claims 93F you can use it.

 

[nickandre]

You can modify any fish tank heater that uses a mechanical thermostat to reach 100 degrees. You just need to MAKE SURE that it's entirely mechanical. By pulling the magnets and coils around it should work. I might be able to find the article when I get home tonight.

I currently just add tap water to a water bath at intervals. If you're off by a degree or two or three you'll still get fine results. 5 degrees is the upper limit before you get crossover. I can keep mine within a degree of the intended temp (I use 102 degrees to compensate for heat transfer between that and my tank.)

 

[tim_walls]

For what it's worth I used to use an aquarium style heater from Nova Darkroom that did the job perfectly, if slowly. I would hazard a guess it's just an 'adjusted' aquarium heater rather than particularly custom made!

More recently though I've fitted an under-sink electric tank heater of the type intended for second bathrooms and the like, and plumbed it up to a basic Honeywell thermostatic mixing valve that I've set to 38C. This gives me plenty of perfectly consistent 38C water - as my hot supply is dedicated I find it works perfectly regardless of any other water use in the house without needing an expensive electrically-controlled mixer or the like.

 

[David Brown]

http://www.phototherm.com/bath.html

OK, they're a little pricy, :rolleyes: but it's the real deal.

 

[panastasia]

http://www.phototherm.com/bath.html

OK, they're a little pricy, :rolleyes: but it's the real deal.

When I started printing in color in the late 70's I used a Phototherm modular system - separate controller, 200w over the side heater, and sensor - and a home made wooden sink lined with fiberglass (for 3 developing trays). I controlled the sink temperature with this system while reading the developer temperature in the trays, that were set in the sink water, with a certified glass thermometer that could read in 1/10 deg F. I could maintain a constant developer temperature to within 1/4 deg F. while working. I doesn't get better than that.

 

[sam_m]

They're in the UK but you could try emailing them and asking if they'll ship to you:

http://www.novadarkroom.com/product/346/Novatronic_Heater.html

 

[domaz]

I second the Won heater- it works very well. Most other aquarium heaters can be modified by breaking or removing the "stop bit" that keeps the temperature control dial from going any farther than 90 degrees or whatever. I always found it kind of risky to mess with those cheap units though. Break the wrong thing and you could end up making your water bath into a shock bath. Another, probably more accurate option, is to get a generic PID controller off EBay and rig it up to a thermopile for the sensor, and a simple (no thermostat) aquarium heating element.

 

[mrmekon]

I just got the Won 150W a few days ago, as recommended by http://www.dunnamphoto.com/

Preliminary tests show it shutting off at ~99.0F, a little bit too cold. My tank might be too big for it to handle, though. I'm using a 14-gallon rubbermaid tub.

 

[domaz]

Actually the Won heater I use is this one. It has a digital display unlike the Won IC. It has no problem letting you set the temperature up to 110F.

 

[ajuk]

H2O do you mean Dihydrogen Monoxide?

 

[Kevin Caulfield]

Yes, also known as "water".

 

[mrmekon]

I was overestimating. My Won 150 was shutting off at 94F. I got a Won 250 today to speed it up, but they both shut off at the same point, right at 94F. No good for color development.

I just opened it up a few minutes ago. It looks like the big knob on the front is a rheostat (variable resistor), and there's a 10k trimmer connected to the thermistor, which is just a variable resistor itself. Resistance decreases at temperature goes up. The rheostat and the trimmer are both connected to a painted IC, but I'm pretty sure it's just acting as a comparator. When the resistance of the thermistor through the trimmer matches the resistance of the rheostat, the circuit shuts off the triac that powers the heating element. Anyway, what matters is my trimmer was set at 1.6k ohms on the 250W unit, and I twisted it clockwise to the end so now it's reading about 5 ohms, or basically a short. There are a couple other fixed resistors in the circuit, so the total resistance is still positive. The effect was that with the thermistor in 99.8F water, the heater shuts off when the rheostat is at about 86 degrees on the dial. I haven't been running it for long enough to see how high it will go, but I'm guessing way past 102F.

Summary: Buy a cheap Won heater, take off the four screws on the back cover, twist the trimmer where the thermometer connects all the way clockwise, and put it back together. It'll probably work. I got mine for $20 shipped on the *bay last week. Not my fault if you kill yourself!

edited: Now with illustration! Confirmed it works the same with 150W. Both were still on at 104F when turned to max.

 

[mts]

I use hot water from the faucet. The water bath easily holds 100F for the 4 min or so of the C-41 developer, and the remaining bleach and fix can be done over a wide range of temperatures because they proceed to completion. I find no need to use any sort of electrical heaters around my sink! I fill the water bath with hot water at around 130F and in a few minutes as it cools the developer bottle is right at 100F, as is the bath surrounding it. As said above, simply start processing around 101F and you will be fine.

 

[fschifano]

edited: Now with illustration! Confirmed it works the same with 150W. Both were still on at 104F when turned to max.

OK. That's good to know. Does the thermostat still work? Can you set it to hold 76 deg F now, or did the mod ruin the thermostat?

 

[mrmekon]

The thermostat still works, but the whole range is shifted. I didn't test the lower range, but it might be unsuitable for B&W temperatures now. The minimum temperature may have bumped up to the 80s. I'll check it out when I have some time.

I kept about 8 gallons of water at 100.5F +/- 0.2 for a few hours in a 72F room, so it looks like it's very stable at the high end.

 

[Tim Gray]

Looks like a winner. I think I'll pick one up soon. Though this one looks nice for not too much more. I don't know where I found the reference to this other one; either here or somewhere else.

heater

 

[fschifano]

Look again. That's just the controller. You'd need to purchase the heating element separately.

 

[Tim Gray]

Noted. Still looks interesting. Here's one with a 300w heater:
controller + heater

 

[panastasia]

You also need something to stir the water. I use a home made sink with a small submersible pump - found in garden supply stores for use in small artificial garden ponds. Also the heater should be matched to the volume of water being heated. Too little and you can't maintain the developer temperature when the room is cold, and too much will make it difficult to hold a set temperature as it will fluctuates wildly. My sink is 2'x4' w/3" deep water and I found that a 200w heater is minimum; 300w is ideal; 400-500w is overkill and raises the electric bill unnecessarily.

 

[nickandre]

I just busted open my heater and it is mechanical even though it says electronic. I'll get to modifying it sometime.

 

[markbarendt]

I have a Tetra Whisper for 30 t0 60 gallon tank.

I moved the knob to the hot end and then pulled the knob straight off turned it back a 1/4 and slipped it back on to the stem. works great.

Got it at WalMart for about $20 I think.