Re: [APML] Film Desiccation

["Bobby Middleton" <bobm@koyote.com>]

Good info Joe. Maybe with a long dry-down with dessicate in the chamber we
can get results close to high-vac dry-downs.
Bobby Middleton


http://www.koyote.com/users/bobm/word.htm
----- Original Message -----
From: Joe Celmer <celstar@frontiernet.net>
To: Post Astro-Photo Message <astro-photo@seds.org>
Sent: Monday, June 05, 2000 12:20 PM
Subject: [APML] Film Desiccation


> Dear APML,
>
> I recently did some gravimetric tests regarding film desiccation, which
> I would like to share FYI.
>
> I oven dried a strip of PPF film at 105 degrees C for 2 hours. The
> weight loss was 3% (repeated twice). One would assume that this loss
> includes moisture and any other volatiles in the emulsion, and may
> represent the maximum potential desiccation loss for the film.  The film
> was allowed curl up freely during drying, and was like a spring when
> removed, similar to descriptions of film desiccated under high vacuum.
>
> I then desiccated another strip of the same film in under "normal"
> vacuum (27" Hg) with desiccant in the chamber, for 4 days. The strip was
> held in a spool. The resulting weight loss of the strip was 2.5 %. The
> indicating desiccant had pink coloration on the edges of many of the
> granules.  The strip was more relaxed in the long direction, possibly
> due to being restrained in the spool, but had a some curl in the cross
> direction.
>
> One might conclude that normal vacuum desiccation can reach over 83% of
> the potential moisture and /or volatile removal of the film.
>
> Comments?
>
>
>
>
> --
> ________
>
> Clear Skies!
>
> Joe Celmer
> celstar@frontiernet.net
> http://www.frontiernet.net/~celstar
>
>
>
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