Re: [APML]: Storing TechPan

[Alfredo Zanazzo <alferd@mbox.lol.it>]

Brad Wallis wrote:> re: ZIP LOCK bags and FG purge or N2 purge for
storing ....
> 
> When you go to store your Tech Pan in the refrigerator or in the freezer,
> the enemy here is moisture....  If you freeze it in a purged hypering
> tank that is *really* air tight that will keep the film the driest and
> will preserve it the best...  If you place the film in a ZIP LOCK bag
> for storage then you should place some dessicant into the bag ( indicator
> dessicant is best since it tells you when it is saturated ) then
> you will keep it dry and help the preservation of the hypered film.
> Purging the ZIP LOCK BAG with FG or N2 is only useful for very short
> storage periods ( like 1-2 days ) as the gas in the ZIP LOCK BAG leaks
> out osmotically and you have your basic AIR in the bag after only 1-2
> days ( tested with an O2 monitor and an N2 purge ).
> 
> Storing the film in N2 or FG in the freezer will preserve the hypered qualities
> the best.  This is a chemical process and thus works as all chemical processes
> work:  If you lower the temp by 6-7 deg C you will slow the process by a factor
> of two ...
> 
> I will add a piece on the Storage of Tech Pan at our WEB SITE, I am trying to
> fill in the need for FAQs for this mailing list.
>        http://voltaire.csun.edu/hints.html
> 
>I knew I was going to catch you in my trap asking easy TP questions.;-)
but now, why dont' you reply to another pertinent question about TP:
you have mentioned that you keep TP in N2 WHILE EXPOSING at the
telescope.
Did I get it wrong or is it a secret?:-) (I have saved that message)

Alfredo
 
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