From: Keith Gerling (keithgerling@att.net)
Date: 06/15/03-09:24:10 AM Z
No, it doesn't smell. But I've been storing it in bright sunlight. Not a
good idea, I guess. I just noticed a warning on the label: "Pure gum arabic
has a limited shelf life. Do not use after six months from purchase". I
guess I had better get busy...
-----Original Message-----
From: Katharine Thayer [mailto:kthayer@pacifier.com]
Sent: Saturday, June 14, 2003 6:17 AM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: a newbie's first post: gum, temperaprint, oil printing,
sizing,and computer negatives
Hi Keith,
Does it smell funny? If not, it's probably not actually souring. As a
general rule, gum that is purchased in a liquid form contains a
preservative (although it's also generally not specified that that's the
case) and should keep for months without souring, if not years. I
suppose the longest it's ever taken me to use a jug of gum was two
years; there was no souring in that time. In my experience, liquid gum
does darken with exposure to light; for that reason I keep my gum jug
covered with black plastic to keep the gum light and clear. The
darkening of the gum doesn't change its functional properties, but since
I mix colors by eye rather than by weight, it's important to me to work
with clear gum that allows me to see the colors accurately when
mixing.
Katharine
Keith Gerling wrote:
>
> On Fri, 13 Jun 2003, Judy wrote:
> > There's
> >also the fact that we don't know what the hell Demachy was using for gum.
> >He probably mixed it himself, it may have been sour, which changes its
> >behavior
>
> How does being sour change its behavior? I recently purchased a gallon
of
> 100% pure gum. 14 baume. It was crystal clear when I opened it last
week,
> but now its turning yellow and I suspect its beginning to "sour". Still
> working fine now, but what should I expect?
>
> Keith
>
> website: http://www.gumphoto.com
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