Temperature Control

[Mickey]

I am new to Large Format but have been doing 35mm and medium format for some time. Since I now have control of individual negative development I want to closely control the temperature during development. My house water is not cold enough to use to bring the temperature down to the right temperature. I have tried ice water baths but that is too unstable.
Has any one encountered and solved this problem?

Thanks

[Ron Marshall]

I hand-roll a Jobo 3006 Expert drum on the $20 Jobo roller base.

In summer I crank-up the aircon, put the Jobo in the fridge briefly, and cool the developer in an ice bath to one degree less than my desired development temperature. By the end of the development time the developer temp is one degree above (I tested this previously, depends on ambient temp.) so the average temp. is what I require.

I could alternatively get stronge aircon that would maintain the air temp at 68, or I could use a higher temp. with a shorter development time. But I prefer not to re-test, and so I stick with the same time.

[Brian Ellis]

"My house water is not cold enough to use to bring the temperature down to the right temperature."

There actually is no "right temperature." While Kodak and maybe other companies specified their times at 68 degrees, it isn't necessary to process at that temperature. You can just as good results at higher temperatures. It's much more important to test and consistently process at the same temperature no matter what it is (within reason of course) than it is to process at 68 degrees. So I wouldn't worry about using ice to bring the temperature down, pick a temperature that is convenient for your situation, test on the basis of that temperature, and use it for all your processing.

[Doremus Scudder]

Brian's answer is right on. If your cold water is higher than 68 degrees F consistent, (say, 74 degrees F) just use that temperature as your standard. You just need to find the appropriately shorter time for the higher temperature. Most modern films can be processed at up to 80 degrees F.

Here is a link to the Ilford temperature conversion chart to help you get started.

http://ilford.com/html/us_english/pdf/tempconv.pdf

However, the above chart is not completely accurate for all developers. I'll take the liberty of quoting David Carper from his response in another forum regarding the Ilford Chart (David worked in the technical dept of Ilford for years and is an authority).

"The tables are based on the combination of ID-11 and FP3 (!). They work quite well with ID-11 and any film; and also work quite well with some other developers, including I think HC110. But some modern developers such as XTol, TMax, or ILFOTEC DD-X do not show the same change in activity with a change in temperature; if you use the chart for these developers, you'll likely end up with underdeveloped negs at higher temperatures. In the last few years, an attempt was made to move away from the charts, and testing was conducted at both 68 and 75 degrees on new films, but the resources were not available to fully test all films at both temperatures. If you are using Delta 400 or 3200, use the times listed in the box; for intermediate temperatures, you can get a pretty good time by extrapolating in a straight line; the variation isn't enough to mess up anything short of scientific work.

If you're using a modern developer and other films, do a little testing. IIRC, for these developers, the chart showed about an extra 50% change over what was really required; so if it calls for 30% less time, test at 20% (but do a test; I'm working from memory here)."

You can find the entire thread at

http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00Ak5S&tag=


Hope this helps a bit.

Best,

[John Bowen]

I live in Richmond, VA and the tap water can be 75 degrees easily during the summer months. I usually try and aviod the darkroom during the summer, but I have found the Zone VI compensating developing timer to be a god send. This timer has a probe that goes into your developer tray (I use tray development) and automatically adjusts the time (faster or slower) as the temperature of the developer changes. I use Pyrocat-HD and the time for my Tmax-400 negatives is 16.5 minutes @ 68 degrees. With my hands in the developer for 16.5 minutes, the temperature rises a few degrees during a normal developing session. The timer speeds up as development progresses and my "16.5" minutes is usually somewhere close to 13-14 minutes of actual time.

This timer has a switch so you can adjust the time for either films or paper. The built in curves were originally programmed for Tri-X and HC-110 dil b and Zone VI brilliant developed in Dektol. I have found that the time/temperature curves for most other films and papers benefit from this compensating timer.

These can be found used on Ebay. I think Calumet stopped manufacturing new ones about two years ago. I have one that is about 15 years old and purchased one of the last new ones Calumet sold so that I would have a back-up should the first one die. I would encourage you to call Calumet if you are interested in one of these. They may still have a few new ones lying around, and the used ones go for almost as much as Zone VI sold them for new 15 years ago.

Good luck,

John

[Bruce Barlow]

eBay prices for the Zone VI Compensating timer have often EXCEEDED what they sold for new 15 years ago (which, if memory serves, was around $400). I baby mine (my second, after my first got zapped when lightning hit our house), and you would have to pry it from my cold, dead hands. It is one of the great inventions of photography.

And while Picker calibrated it for Tri-X and HC-110 for film, and Brilliant and Dektol for paper, it will get you far closer to accuracy with any other combination than nothing.

[Jim Jones]

I tray to maintain the temperature of the darkroom between 68 and 75 degrees. Chemicals, tanks, and wash water are stored in the darkroom, and should stabilize at a practical temperature. Developing time is adjusted to accomodate the ambient temperature.

[paulr]

I'm not a fan of compensating timers, because in addition to costing a lot, they assume that all developers respond the same way to temperature. Which isn't the case. Hydroquinone is much more temperature sensitive than metol, for example. It has a steeper activity/temperature curve, and actually becomes innactive below 64 degrees or so. So a developer with a higher proportion of HQ to metol will respond to temp changes differently one with a lower proportion. And very differently from a metol only developer. And this is just one example using a couple of the most popular developing agents.

If you're going to compensate, it's best to test your individual developers at a few different temps, and write down the results.

Since I've always had darkrooms with huge temperature swings from season to season, I find it easier to just do it all at 68. Hot water bath in the winter, ice water in the summer. It's second nature ... easy to keep everything within a half a degree, no matter lattitude it feels like in the room.

[Mickey]

Thanks for the helpful hints.
I'll look for the Zone VI Timer and I will use the temperature conversion chart.

Mickey

[jstraw]

I wonder if those of us with Zone VI compensating timers could work together to develop a set of tests for other common chemistries besides HC 110 and Zone VI Print Developer so that we could do better than just guess that the device works better than nothing with other formulations.

Where would one start? Was Paul Horowitz involved with designing this product?

[paulr]

It would just take 20 minutes or so to test one. Use water starting at 60 degrees or so, and with a regular clock or timer, figure out how much it compensates. Warm up the water a bit, and repeat. Do it up to the highest temp you care about. You can graph the results and see the built-in response curve.

Testing your various developer formulas is actually simpler than you might think. You can testt them with test-strip sized bits of photo paper, all given identical, brieff exposure. Under constant agitation, time the point at which the image first emerges, and record it. Repeat at different temps, for the developers you're curious about. Graph the results for each developer.

This works because it's been demonstrated that the emergence time of an image is directly proportional to it's total developing time. Even if this isn't precisely true, it seems to be close enough to provide a good working model.

You can compare your curves to the one the compensating timer gives you. My guess is the timer was calibrated for a middle of the road metol-hydroquinone formula, since that would be close to what most people use most of the time.

There's no doubt the compensating timer is bettter than nothing. I'm sure it's much better than nothing. It just strikes me as a lot of $$$ for something that's actually less accurate than a post-it note worth of of your own test results.

[jstraw]

It would just take 20 minutes or so to test one. Use water starting at 60 degrees or so, and with a regular clock or timer, figure out how much it compensates. Warm up the water a bit, and repeat. Do it up to the highest temp you care about. You can graph the results and see the built-in response curve.

Testing your various developer formulas is actually simpler than you might think. You can testt them with test-strip sized bits of photo paper, all given identical, brieff exposure. Under constant agitation, time the point at which the image first emerges, and record it. Repeat at different temps, for the developers you're curious about. Graph the results for each developer.

This works because it's been demonstrated that the emergence time of an image is directly proportional to it's total developing time. Even if this isn't precisely true, it seems to be close enough to provide a good working model.

You can compare your curves to the one the compensating timer gives you. My guess is the timer was calibrated for a middle of the road metol-hydroquinone formula, since that would be close to what most people use most of the time.

There's no doubt the compensating timer is bettter than nothing. I'm sure it's much better than nothing. It just strikes me as a lot of $$$ for something that's actually less accurate than a post-it note worth of of your own test results.


Thanks, that's very helpful!

One thing you should keep in mind is that the impetus isn't just to compensate for a constant temperature that diverges from 68 degrees, it's to compensate for temperatures that drift over the duration of a session.

[PViapiano]

When it gets too hot here in southern California, I sometimes put a large pyrex or two of water in the fridge and temper the amount needed at processing time with warmer tap water.

[paulr]

Thanks, that's very helpful!

One thing you should keep in mind is that the impetus isn't just to compensate for a constant temperature that diverges from 68 degrees, it's to compensate for temperatures that drift over the duration of a session.

Definitely. Although I find this to be much more of a concern when printing than with film. Film processing is quick and easier to control, so I just hold the solutions at the same temperatures. With prints I check the temp whenever I put a new sheet of paper in the soup and compensate accordingly. It's not going to drift significantly in the time it takes to develop that one print.

[Alan Rabe]

I used to live in Arizona and developed a trick. I use 8x8x1 inch blue ice containers. Depending on the tray size I take them out of the freezer place a wet lab towel over them to help in the heat transfer and to keep the tray from sliding around. Once the liquid gets down to teperature they will maintain an even temp thru out the developement cycle.

[Harold_4074]

A very nice way to handle single sheets is to use something like divided D-23 in one-liter tanks with sheet film hangers. If your darkroom is near process temperature, you can adjust the solution temperature before starting and it will not drift appreciably during one development cycle. A plastic ice chest makes a good container for blending tap and cold water to the target temperature, and with a suitable rack it will also make a decent water jacket (with "thermal inertia" even better than a single tank).

If you are going to routinely do single sheets, you should probably plan on using either a one-shot developer or a sufficiently large amount that the exhaustion by each individual sheet is negligible (hence the D-23 suggestion). With one-shots, the volume needed for handling will probably be large compared to what is needed chemically, and with the large-tank approach you will have to deal with developer that is slightly different (exhaustion, oxidation) each time. In either case, when you have everything dialed in and decide to do four or six sheets at once, you should expect lower density and less contrast! Of course, there are also replenishers to introduce additional uncertainty....

The tray-within-a-tray tempering bath certainly works---if the humidity in the dark room is high enough that the dew point is close to process temperature! In my neighborhood it is dry enough that a tray of 68F water will cool by several degrees in the time that it takes me to presoak and develop one sheet of film; this is, after all, the principle that evaporative coolers work on.

All things considered, tanks and hangers are probably the easiest solution; your (warm) hands stay out of the solution, there isn't much surface for evaporation, and the since you are handling the hangers and not the tank (unlike 35mm/120) body heat doesn't enter that way either. Make up the solutions with 75 degree water, and stand the tanks in a couple of gallons of water at the same temperature, and you should be able to concentrate on all of the other sources of variation with a clear conscience.

[Wayne]

I am new to Large Format but have been doing 35mm and medium format for some time. Since I now have control of individual negative development I want to closely control the temperature during development. My house water is not cold enough to use to bring the temperature down to the right temperature. I have tried ice water baths but that is too unstable.
Has any one encountered and solved this problem?

Thanks


get a chiller and install it into a water tray that your developing tray fits in.

http://www.jbjnanocubes.com/index.html?lang=en-us&target=d782.html

I was going to try it myself this summer. I didnt have time for darkroom in the summer, but I dont see why it wouldnt work.


Wayne

[Ed Pierce]

My experience with the z6 compensating dev. timer is that they are not all identical. I have two of them, and three sensors, and I've run them in various combinations together. One always runs just a little faster than the other.

Calumet still sells replacement sensors, but they are not the original plastic ones with the clamp.

It's a very helpful device, but I still make sure that the solution is at the same temperature for every run, just to be sure.

[Donald Miller]

I wonder if those of us with Zone VI compensating timers could work together to develop a set of tests for other common chemistries besides HC 110 and Zone VI Print Developer so that we could do better than just guess that the device works better than nothing with other formulations.

Where would one start? Was Paul Horowitz involved with designing this product?


Yep Horowitz was involved...to the best of my knowledge.

This testing would require a ton of work to see how the timer's curves would match the temperature correlation with all of the different developers used today. I use mine with Pyrocat and have no problems maintaining the negative DR I want with temp variances ranging from above 90 degrees in the summer (cold water temp) to a more normal 65 winter (cold water temp) but I do use ice in the summer.

[Mickey]

Wayne suggested a water chiller and I think that might be a good investment. I can also use it to cool my outside aquarium on those dog day summer afternoons here in Florida.
Thanks

[Wayne]

If you try it, let us know how it works


Wayne

[Don Wallace]

The simplest method of temperature control is a Jobo. I have an older CPE-2 that I bought used and it works great. This model only raises the temperature but if I put ice in the water to take it way down, the heater mechanism kicks in, and I can maintain a temperature below the normal tap water temperature quite easily. You can also develop at a higher temperature which makes the work of the Jobo even easier. I use 68F as a standard only because most of the year my tap water is around or below that.

[Dan Jolicoeur]

I simple way to make a chiller is to take a smalll dorm size refridgerator. I have one here in my office I put my lunch, and drinks in.

All you have to do is make a copper coil around a 3" in pipe maybe about 3"-4" long, and run that into your bath/tank, jobo or whatever you are using.

Chillers can get very expensive. You can get a refregerator guy to make this for you for about $50-$60 bucks if you can do some of the pre work of coiling the line so they just have to put a couple shut of valves and solder this line in to the loop. Close the valves and it can still be used as a beer fridge for the dark room!

Just a thought,
dan

[Leonard Evens]

Every film data sheet I've ever seen includes a chart telling you how to adjust development time for different temperatures. My experience is that these methods work pretty well. If you use something other than one of the standard developers specified in the data sheets, there are general rules about how to compensate, and one of the above responses gave a link for that.