Marilyn,
All chemicals change their speed of operation with temperature.
Unfortunately they do not all change at the same rate. Hence there is a
limited temperature range over which you can develop and still get basically
the same result (density, contrast range etc.)
Another problem, particularly with older films, is reticulation, the gelatin
emulsion layer shrinking or contracting with rapid changes of temperature.
Hence it is usually recommended to maintain a constant temperature for
processing, and if washing later, have a gradual change to the tap water
temperature at the start.
The Darkroom Cookbook by Stephen G Anchell (Focal Press) has some tropical
developers listed, for processing up to 105 F or 40 C. I suggest you get a
copy of the book, it has a number of references to tropical developers, as
well as modifying developers for tropical use. He also refers to stop bath
for tropical development.
Thought I had seen other references to the problem, but cannot locate them
at present.
Hope this helps, get back to me with any more queries,
Jim Thyer
----- Original Message -----
From: "Marilyn" <marilyn@xxxxxxxxxxx>
To: "List for Photo/Imaging Educators - Professionals - Students"
<photoforum@xxxxxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, August 16, 2005 12:37 PM
Subject: film processing chemicals
Hi All,
I need your help again, please.
Here in the southern California desert cold water coming from the tap is
sometimes 85 degrees. This is hot for processing black and white film
and the times/temperatures on the back of the chemical bottles only go up
to the temperature of 75 degrees. Is there a formula for figuring
adjustments for processing film in warmer water? I can cool water down
by adding cold water from a water cooler, but I need such large amounts of
water to process film, that this becomes difficult.
Using bottled water causes temperature problems, too. Even at room
temperature the water is very warm.
And nooo - I can't switch to digital. I have students who want to learn
film and darkroom work (thank heaven for these students{:->)
Marilyn
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Let no one come to you without
leaving better and happier.
Mother Teresa
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