Temperature control in C41 - manual process

hpulley

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I prefer plastic Paterson tanks for C-41, they hold the heat very well and more importantly they don't leak all over the place. I still have 1L of solutions after 24 rolls! Temperature drops very little.

Thin plastic bottles heat up fairly quickly but thick ones take too long to heat up.
 

little-infinity

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It's currently 38C outside here. An excellent day to take in the (not so) fresh air and do your C-41 outside! Just a heads up

All jokes aside, I doubt taking your chems outside on hot days like today would be feasible enough. Would it?
 
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Mike Wilde

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I run my water bath in a cooler that holds about 12L of liquids, between the 1L plastic or glass chemical storage bottles and the surrounding water bath.
I have it fitted with a 300W aquarium glass tube immersion heater and aquarium water pump to ensure the water bath stays moving and unithermal thoughout the bath.
The OEM stops on the mechanical thermostat have been broken off to allow me to set it to 39C.

There is not enough room in this small water bath at the start to warm the fixer bottle when I run E6, but it warms to 32C by sticking it in after the CD has finished.
The up side to the small water bath is that it is easy to empty and store when it is not needed.

I keep the stainless 1L tank in the water bath between agitations.

I find that chemistry will come from 18C to 38C in about 1 hour or so, when you start with a pre heated water bath. This is achieved by using mostly the hot water tap to yield a 45C mix. agitating the developer bottles after a few minutes help if you store developers in glass.

Left overnight with the lid mostly covering the top, there is no problem keeping temperature, even though in winter the house thermostat drops back to 16C.
 

Diapositivo

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That's very interesting, but very challenging for the DIY-challenged like me. I looked on search engines for PID-thermostat, PT100 sensor, I get what you mean, but how do one assemble all those things?

A PID-thermostat is something that controls boilers. How do I connect it to a heating element?
A PT100 sensor is shown (the one I found) with some kind of a round connector. How do I connect it to the PID-thermostat? Is the thermostat voltage-dependant? Do I need to earth some of the above?

Is there somewhere (maybe here on APUG, or somewhere else) a "dummy guide" that specifies exactly what one must look for (without margin for buying errors) and how to connect all the pieces, without margins for fires and shortcircuits? A guide that lets you go to the home-improvement store with a list of things to buy, and lets you assemble them at home, unfailingly well?

Things that look easy for those who know, look mysterious for those who don't know, you know
 

olleorama

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It's not really that hard. My pid-thermostat had screwconnectors for all cables. All you need is cable stripper pliers (or a knife/scissors) and a small screwdriver. But my thermostat is not chinese, so I don't know how to hook those up, some of them need an external relay, mine has an internal relay. I can take some pics in the morning if you like. The things you need aren't found in a home-improvement store though, I'm afraid. Well, maybe you can find a cooler that you can use.

The ebaystore mixtea has sensors, SSRs and thermostats. The sensor is easy to hook-up, just remember to use shielded cable if you need to extend the cables. The thermostats he sells must be used with a relay, use a solid state one (SSR). There is a pdf on sestos site which tells you which terminals to use.

Basically you screw or solder the SSR (solid state relay) on to two terminals, your mains cables on to two terminals, and the sensor on to two terminals. And then you hook up your heating element to the SSR and mains (depending on how the SSR looks). Easy peasy.
 

nworth

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The really critical step is the first developer (E6) or developer (C41 and RA4). You can usually manage to get the developer to some known high temperature before you use it, at least for a few minutes. The instructions for the original Mitchell Unidrum (same as Beseler, but a bit earlier) included a chart for the drift through method for processing prints. If you know the room temperature and the development time, you could look up a starting temperature for the developer that would produce good results as the developer cooled down and drifted through the target temperature while you developed at room temperature. You usually started at something like 104 (for 100 F processes) or 77 (for 75 F processes). The idea would probably still work for film and prints, but you might have to do some experimenting to determine the right starting temperature. The other solutions all work to completion and are less critical for temperature. Plus or minus 2C is usually OK. It is pretty easy to build a solution warmer to keep solutions at a elevated temperature. Start with a container that will hold the bottles with some room to spare (fish tank?) and use a fish tank heater with a built in thermostat to maintain the temperature. It works quite well.
 

Diapositivo

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Stock fish tank heaters never arrive to 38 °C because fishes would not survive at that temperature. So if you use a fish tank heater you have to modify it (read: break the temperature limiter) so that it can reach 38 °C.
 

ChrisC

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Thankfully my gas hot water has a digital temperature regulator on it which is pretty stable, so I use that for the pre-soak (usually a 2 step bath, just to make sure), then I just heat up my chemicals in an old microwave until they're 1ºC or so warmer. While the developer's doing it's thing I get a stop bath running from the tap water while heating up the blix in the microwave, then it's all downhill from there.

Eventually I'll make one of these http://www.youtube.com/watch?v=suQTE3wx_Jk with a water heater/thermostat inside it to make everything idiot-proof (which I could probably do with) and I'll be away laughing. I'll probably forgo the relay and just put in a manual reversing switch like I have in my current motorbase, though I've run it without reversing before and didn't notice any adverse effects.
 

fumblingwithfilm

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How to guide on temperature controlled water bath


I saw this post a while back and it stuck with me. Eventually I decided to try it out and I've found a lot of success with it. I put the water in the bucket, turn on the system and it regulates the temperature to whatever I set. I've developed many rolls of c-41 with this system, and it's always at 39C, no matter what.

I've written up a tutorial on how to make your own system using the basics that olleorama laid out, with some additional information pulled from home-made sous-vide machines. Like he said, it's a pretty simple setup that won't cost too much to put together. In the end you'll have a highly reliable system that will make your life easier.

Check out my site for the tutorial:
Dead Link Removed
 
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chassis

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Adding to this thread:

I use a typical picnic-style plastic cooler as the water bath and processing tank/sink, approximately 50 liter/ 48 quart size. No electric heater is needed. The important piece is the use of an insulated tempering bath, which in this case is a cooler. This process is carried out in a walk-in shower where ready water supplies and drains are available.

Mise en place:
- cooler as noted above
- chemistry in 1 liter plastic bottles
- film developing tank (I use a Paterson System 4 tank)

Place all chemistry bottles in the cooler, fill with 125-130 deg F water, nearly to the necks of the chemistry bottles. This is the maximum temperature I can achieve at home. Close the top door (lid) of the cooler. The chemistry arrives at 105 deg F in 5-7 minutes. Measure the developer temperature, and wait, if necessary for the temperature to arrive at 105 degrees F.

Open the cooler lid and drain tempering water out through bottom drain in cooler, to the depth slightly less than the cover of the Paterson tank. Place the Paterson tank, with film, into the bath, and weight it with, for example, the rinse solution bottle. In 5 minutes the film and tank will be warmed.

Start the C-41 process when the developer reaches 101-102 deg F. During the bleach step, drain 2 liters of tempering water, and add 2 liters of water at 110 deg F. Again during the fix step, drain 2 liters of tempering water, and add 2 liters of water at 110 deg F.

Using this method, tempering bath temperature has never been lower than 102 deg F. I am pleased with the film results so far. I have processed 4x5 film with this method, and plan to use it also with 120 and 35mm film.
 

GregW

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I've started using a surplus laboratory water bath from Labline, there's a whole category of water baths on ebay under lab equipment. They can go for very little money. Mine was 17.99 and 22 for shipping. it's about 20" x 20" x 10"? or so. Stainless steel. Some have digital temp readouts, mine is just a dial that the scientist who had it before me marked with temps. I fill it up put the lid on it and leave it for a half hour then return, stand or float my chem bottles in it, wait another half hour everything is at the perfect temp and I can go from there. I set my tank inside when i'm not agitating. I dip water out of it to rinse between steps. I'm using a SP-445 btw. sometimes I stand a couple pitchers of water in for rinsing to make it easier.
 

Gerald C Koch

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If you read the Kodak instructions the temperature latitude is given for each step of the processing for C-41 and E6.
 

Gerald C Koch

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brucemuir said:
I agree for C41 Jerry,
I'm still on the fence for E6 though.
The longer times can drift a but with ss but plastic doesn't loose the heat so fast.
Click to expand...

I have processed many rolls of color film including today's C-41, E6 and ECN. Never had any difficulties. It certainly helps to follow the French cooking dictum mise en place. Have everything in place before you start.
 

Chan Tran

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It's easy to make the water bath but even with the water bath the temperature drops during processing.
 

Gerald C Koch

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Chan Tran said:
It's easy to make the water bath but even with the water bath the temperature drops during processing.
Click to expand...

There are several ways around this problem. A bottle or tank of hot water in the bath will help keep the temperature up. I also check the temperature often and add hot water directly to the bath. The times for the first developer are so short that this is really not a great problem.
 

chassis

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I agree with Gerald. Temperature of my tempering bath is 102F after the full C-41 process, ending with the rinse step. Temperature of the film-developer interface cannot change in a meaningful way, even when the tank is removed for agitation. The short agitation time and thermal mass of 1 liter of chemical + film + reel + tank will not result in a meaningful temperature drop.

Excluding the, short as noted, developer step, the rest of the process proceeds within Kodak temperature specification when using a sufficiently large and replenished water bath.
 

mklw1954

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I use a small 6-pack cooler as a water bath for keeping the tank temperature constant.. Of course, stainless steel tanks and reels are better for temperature control. First I bring the tank/reels/film to 102F in the water bath before chemical addition, using a digital thermometer with a wire probe in the water. I start off with water at about 104F and, as the tank warms and the water cools, add small amounts of hot water, as needed, to bring the tank to 102F and maintain that temperature. I use an Extech TM20 digital thermometer with a wire probe, calibrated to a color thermometer. When the water bath temperature is constant the tank/reels/film have attained the 102F temperature. During development, small amounts of hot water are added to the bath to maintain 102F. Subsequent steps have some leeway in the 102F temperature so you just need to stay within the range for bleach-fix and washing.

Using a separate digital thermometer, I bring the pre-soak water and chemicals to temperature in a pot of very hot water and start when the tank and the chemicals are at 102F. I monitor each chemical's temperature before addition, placing the bottle in the hot water pot again if necessary before use.

I use Unicolor powder kits and get great results. Development is sufficiently consistent because, for the same film, I am able to use the same enlarger color filtration settings, making RA4 printing easier.

I use this approach to temperature control for black and white as well.
 

Chan Tran

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I have no problem keeping the temperature of the bath constant. But when I pour the chemical in the tank even the tank is in the bath the temperature still drops.
 

Gerald C Koch

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Chan Tran said:
I have no problem keeping the temperature of the bath constant. But when I pour the chemical in the tank even the tank is in the bath the temperature still drops.
Click to expand...

Are each of the solutions at the correct temperature? They should each be brought up to temperature and also be in the bath before you start.
 

bvy

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A water bath will work fine, but you should do some testing in advance since there are a lot of variables at play (ambient temperature, tank material and size, water bath container and volume, etc.). You can do a simulation with empty reels in your tank. First prepare a water bath of water at X degrees (X is what you're trying to solve). Use a probe thermometer to measure the temperature of the developer itself; the thermometer should sit in the developer until you're ready to use it and should be gently stirred occasionally. When the developer is at 101F, pour it into the tank. Agitate as you would normally, replacing the tank in the water bath between agitation cycles. Afterwards, pour the developer out and immediately probe its temperature. You want a temperature of around 99F. (I'm allowing a one degree drop for pour in and pour out.) Whatever X returns the developer at 99F is a good starting point. For your simulation, you can use water in place of developer. Remember to hold certain things constant: use the same water bath container and same volume of water, use the same volume of developer and the same development time. My X's are 105F for a tall (two 120) stainless steel tank, and 120F for a standard (two 35mm) Paterson tank. I use a small Playmate cooler with water maybe two inches deep and 600ml of developer.
 

mnemosyne

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For meaningful results, it's better to probe the temperature in the tank. It's the only way to actually know at which temperature you are developing. So fill the tank, do the initial agitation cycle, replace tank in water-bath, pull the cap and do a quick probe with a pre-warmed digital thermometer. Then process as normal and do a second probe at the end of development just before pouring. The two numbers will show you a couple of things: First, if your actual processing temperature is in the ballpark. Second, how much the temperature of the developer will cool down during filling the tank (depends on ambient temperature, see below). Third, how much the temperature will drift during development (depends on the temperature of the water jacket and ambient temperature).

As noted by some, pouring liquid in and out WILL change the temperature of the liquid depending on the ambient temperature and other factors. I did some testing and IIRC at 20 C ambient temperature have recorded a temperature drop of as much as 2 C between the temperature of the developer before filling the tank and later in the tank after the initial agitation cycle, even if the tank was in a water bath and had been brought up to temperature by 3 cycles of prewet @38 C with one minute each. But I should add that I prefer to fill the tank outside the water jacket.

What you do is that you finetune the prewarm temperature of the developer solution up to the point where your test show, that after the initial agitation cycle you have a temperature of 37.8 C within the tank; then you finetune the waterjacket temperature to the point that the temperature at the end of the 3m15s has not drifted too far from the 37.8 C. IMHO this is really the only way to do it. Simply adjusting the water bath temperature and the temperature of the developer to 100F/37.8C and hoping that the temperature inside the tank will also be 100F/37.8C is a bit overoptimistic.
 

Harry Stevens

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