From: Katharine Thayer (kthayer@pacifier.com)
Date: 02/24/03-01:00:26 PM Z
Well, there you are. Go figure.
Christina Z. Anderson wrote:
>
> 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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