From: Richard Knoppow (dickburk@ix.netcom.com)
Date: 01/21/01-04:55:50 PM Z
Date: Sun, 21 Jan 2001 17:33:45 -0500
From: "Robert W. Schramm" <schrammrus@hotmail.com>
Subject: Re: film reticulation and lens website
To: alt-photo-process-l@sask.usask.ca
Reply-to: alt-photo-process-l@sask.usask.ca
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Comments: "alt-photo-process mailing list"
Judy and the group,
I tried for some time, without success, to reticulate film. At the time I
was using Kodak T-Max films. More recently I have switched to Illford
films, viz. Pan, FP4, HP5. I discovered, accidentally, that these film
recticulate very easily. Almost too easily. I use these films with Xtol
developer.
I have been told that the Kodak films have built-in hardners and the Ilford
films do not. Perhaps that is the reason.
Bob Schramm
All film has some hardener added in manufacture, although it is different
hardener than that used in fixing baths. Its possible that T-Max films also
have some plastic added to the gelatin. T-Max films are hardened like color
films to take 100°F processing, Tri-X and other older type films are not.
The hardener can be undone by treating the film in a bath of carbonate,
about 2% to 5% before trying to reticulate it. Dektol will work if you
don't have carbonate. The alkaline bath makes the gelatin swell and undoes
some of the cross-linking caused by the alum.
Emulsions have become increasingly harder as emulsion making progresses.
Until about 1940 the standard temperature for processing was 65F, at that
time it was raised to 68F, not a big difference, but it indicated that the
emulsions were less vulnerable to damage. Most modern emulsions can
tolerate temperatures up to about 80F, and, as above, some films are
hardened to take 100F processing.
Reticulation is caused by softening and swelling of the gelatin. This can
be produced by both high temperatures and sudden changes in pH such as
going from a hydroxide high contrast developer into a strongly acid stop
bath even when both are at the same temperature.
---- Richard Knoppow Los Angeles,Ca. dickburk@ix.netcom.com
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