From: Sandy King (sanking@hubcap.clemson.edu)
Date: 02/01/01-06:34:17 PM Z
Nelson Goforth wrote:
>I tried the BTZS tubes for three sets of negatives (mostly doing the tests
>to determine proper dev time), and liked them save for one problem - I got,
>on at least one neg per batch of 6 - flaking of the emulsion. One small
>flake (not a scratch, but an irregular flake) that had come loose and then
>laid back down on the emulsion.
>
What caused the flaking of the emulsion in your use of the BTZS tubes is a
mystery to me but but this is a very unusual problem. What film was it?
Some films have very soft emulsions that will flake off rather easily, FP5+
for example.
I don't use BTZS tubes but I do develop in tubes, in tubes made from ABS
plastic for 5X7 and 6.5X8.5, and in print developing drums for 7X17 and
12X20 film. I find this type of development highly consistent and reliable.
Phil Davis pionered the use of film developing tubes because tray
processing was simply too inconsistent for sensitometric use in his BTZS
sensitomety workshops. As is commonly known, uneven development is very
common with tray processing, for a variety reasons I won't go into here.
Persons with refined technique who understand the nature of the problem
inherent in tray processing can come close, but in my opinion not exceed,
the level of eveneness possible with rotary develoment in tubes.
I switched from tray processing to tube processing a number of years ago
and have never looked back. I prefer it for the following reasons.
1. Most of the film processing can be done in the daylight. After many year
of working with photography I have a profound aversion for standing around
in the dark for long periods of time.
2. With the larger film, which is rotary processed in tube on a motor base,
I am free to do other things while the film is developed.
3. Development in tubes has almost entirely eliminated the problem of
scratching and gouging of the film that plagued my tray processing.
4. Development in tubes by rotary processing gives more even development
than tray processing.
Sandy King
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