From: Christina Z. Anderson (zphoto@montana.net)
Date: 02/24/03-08:28:37 PM Z
Shoot; OK, this is the quote:
"The clearing step is intended to remove dichromate residue, not hardened
gum, but as a matter of fact sodium bisulfite does soften the hardened gum,
too. The "various sulfites and sulfates" which clear dichromate stains have
different qualities, being different compounds, and while they may be
roughly interchangeable for the purpose of clearing dichromate stains, they
are not interchangeable in all respects. Sodium bisulfite, by many accounts,
is the strongest and most likely to soften and lift the hardened gum, which
is why I recommended it for gum removal, and why something like potassium
metabisulfite, which removes dichromate stains but isn't so likely to
disturb the hardened gum, would not be useful removing hardened gum. Sodium
bisulfite, having rather strong fumes, should be used outside or in a
well-ventilated area."
----- Original Message -----
From: "Katharine Thayer" <kthayer@pacifier.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Monday, February 24, 2003 11:08 AM
Subject: Re: gum printing
> Christina Z. Anderson wrote:
> >
>
> > I also notice Livick uses a 1% pot metabi clear, because it doesn't
> > soften the gum like sod bisulfite, which is what you, Katherine, said a
> > while back.
>
> I said that? I don't remember saying that, and without context, I don't
> know why I would have said it, since in my own practice, I haven't found
> that sodium bisulfite softens the gum appreciably, once it's been
> hardened. I mean it probably does a little, but not enough to be an
> issue, certainly not enough to change clearing agents over. Since I
> haven't used a clearing agent much, my experience probably isn't enough
> to judge by, but I've never had the image softened or lifted by the
> sodium bisulfite.
>
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