Water temp.

[underground]

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does anyone Know of a device that will control water temp. for darkroom

or home use? or a good technique to do this without such a devise for

color negative development?

 

Thanx in advance

Dave Mac

[andybarton]

Very hard to do unless you have a Jobo water bath with a thermostatically controlled bath

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There are thermostats for fish tanks. I don't know if they're accurate enough, though.

[DOUG66]

Have a look at my post on this forum "Them. compensation of E6 and C41 processing using a HP 48G calculator". I have never used a temp. controlled bath and have been using this method for at least 25 years. It is reliable and produces very consistent results.

Doug.

[underground]

Doug, So as the temp. drops you compensate developing time with your

formula?

 

I am Green with this, and it's a little over my head. I have not done this in

many years.

 

also just for fun, I have a Iron tea pot that holds 720ml of water. I ran 100 deg.

water in it and put it on the stove under low gas flame until it raised to 110 deg.

Then i shut off the gas and it dropped one degree in 6 min. 30 sec. That's much

better than my plastic container.

 

The plastic container melted all over stove and made a hell of a mess.

[Jeff S]

Don't know about color, but for b&w there are certainly temp regulators for sinks...either built in on as separate add-ons. Companies like Delta and Arkay have these, along with some others.

 

The old Zone VI had a device (compensating developing timer) to attached to a developing tray and adjusted the time (based on a given temp) over a long print session if the temp varied up or down. These might be available used, and I think that another company might produce something similar (can't recall where I saw it).

 

None of this is necessary really for b/w if the water temps in your area are reasonable and stable, and if your print sessions aren't incredibly long. I lived in one area (high desert) where the water temp would vary greatly depending on season and time of day. I needed to be watchful for both film processing and print making.

 

Jeff

 

PS Here's something I Googled...http://curtpalm.com/Software.html

Edited April 17, 2010 by Jeff S

[DOUG66]

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Hi Dave,

The method is based on Newton's law of cooling, in which the rate of cooling

is dependent on the difference in temperature between the developer temperature

and the room temperature. The temperature is measured at five time intervals

and a cooling curve is established. This is then used to predict temperatures

over the full range of developing times. The activity curve for the colour

developers is known ( it is the same for both E6 and C41 developing agents

as they are similar ammine compounds, note that one of the constants is 10 PI ).

A numerical integration of the effective development time over short time intervals

is then carried out, which results in the required development time.

The method is independent of tank type and volum of solution used and is simple

to use.

I originally wrote the program in Basic for a BBC computer, but I had a power out on a

night when I was developing some films, needless to say the results were not up

to standard as I had to use guesswork. I then moved to a HP 48G battery powered

programmable calculator and the programmes are written in RPN assembly language.

I use a calibrated +/-0.3 deg mercury thermometer but in the last number of years

I have used a Hamilton digital thermometer which reads to 0.1 deg C and is acuarate

to +/- 0.3 deg C.

 

Doug.

[sulskyr]

I recently purchased a Delta Water Temp II with Temperature Lock for ~$60 at B&H. This is a device that monitors (but does not control) water temperature. It is simply a valve with a large dial thermometer. The temperature probe sits in the water stream. It is much less expensive than a thermostatic regulator and, for my purposes, seems to do a good job. Once I adjust the hot and cold water taps to the desired temperature, I can open and close the valve as needed. Temperature variability over the course of a day's work in the darkroom has been negligible.

 

 

 

 

 

Delta

Water Temp II with Temperature Lock

 

B&H # DEWTMfr # 65010

 

Price:$59.95

[earleygallery]

There are thermostats for fish tanks. I don't know if they're accurate enough, though.

 

I used to do this for my colour chemicals, it worked well enough.