Re: [APML] Air vs O2 vs N2 vs ....

["Bert Katzung" <katzung1@attbi.com>]

Ah, dry AIR! Very different!! Air is "only" 20% O2 and 80% N2. Drying air
and flowing it over film has been used for some time (I think Herm Perez
introduced it and popularized it with a good illustrated write-up on his
website. See http://home.att.net/~hermperez/dry_air_purge_setup.htm. This
was as a substitute for nitrogen or forming gas.
It's apparently the moisture in the _film_ that's important in reducing
sensitivity (increasing reciprocity failure) and causing film creep and
other focus-damaging effects.
Bert

Bert Katzung
katzung1@attbi.com
www.astronomy-images.com

----- Original Message -----
From: "Joseph/Leslie Schaefer" <schaefer@htva.net>
To: <astro-photo@seds.org>
Sent: Monday, August 26, 2002 11:29 AM
Subject: Re: [APML] Frist images with my C11


> I should have pointed out that Jim's system force surrounding air through
a
> desiccant canister to
> remove the moisture. The dry air prevents moisture form forming inside the
> camera body.
>  Here is Jim's system:
>  http://flyboy999.freeyellow.com/LinksPage/PurgeSystem.htm
> Joe.
> ----- Original Message -----
> From: westergren <westergren@netzero.net>
> To: <astro-photo@seds.org>
> Sent: Monday, August 26, 2002 2:13 PM
> Subject: Re: [APML] Frist images with my C11
>
>
> > Joe,
> > I would recommend using dry nitrogen rather than oxygen for a camera
> purge.
> > The pure oxygen creates a fire danger within the camera, and I think it
> > could affect the film over a period of time.  I say the film might be
> > affected based on the idea that we hyper film to get better response by
> > displacing the oxygen in the film substrate with the hydrogen in forming
> > gas.  Nitrogen would be completely neutral to the film and camera.
> Nitrogen
> > makes up 92% of forming gas in the hypering process, and is used
> > specifically to eliminate the fire danger of the hydrogen gas.
> > Don
> >
> > From: "Joseph/Leslie Schaefer" <schaefer@htva.net>
> > Subject: Re: [APML] Frist images with my C11
> >
> >
> > > No I'm not using any kind of purge system yet. I'll read over the
latest
> > > purge string.
> > > I think I'll start with a dry Oxygen purge system first. Jim Ives is
> using
> > > one that he made and the
> > > price for the hardware is reasonable.
> > >  Do you think the color in my images would benefit from a dry Oxygen
> > purge?
> > >  Thanks, Joe.
> > >




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