From: Judy Seigel (jseigel@panix.com)
Date: 01/26/02-08:06:07 PM Z
On Sat, 26 Jan 2002, Bob Kiss wrote:
> The old Hypo Eliminators, made by both Kodak and Heico contained ammonia
> and hydrogen peroxide. Some researchers said that they eliminated TOO MUCH
> sulfur (usually in the form of Silver thoisulfate complexes) and minute
> trace amounts of sulfur were actually better for image permanence. They
> also said that residual ammonium peroxide may be left in the image which
> also might be bad for print longevity.
Yes, Bob, that's what I was referring to. Tho I didn't recall the details
as precisely as you state them here, I did remember that hypo eliminator
was eliminated, or supposedly so. Which was why I raised the question,
because, hypo eliminator was cited as a possible option, making me think
it was reinstated, & I wondered about that. Is that perfectly clear?
I recall some tests by David Vestal, or maybe he was simply citing tests
by others, that showed a certain amount of residual hypo (ie, sulfur) did
improve longevity (as you note below), but the archivalism-for-dummies
explanation was that by sulfiding the silver with the sulfur residue, the
acid or whatever effect from bad air was cut.
cheers,
Judy
> Hypo clearing agent contains, among other things, Sodium sulfite, EDTA,
> and Sodium meta borate, all pretty benign stuff that gets the
> sliver-thiosulfate complexes out via both a replacement reaction (leaving
> behind the trace amounts of "good" sulfur) and by moving the ph of the
> gelatin zwitter ion (has a basic ion at one end of the molecule and an
> acidic ion at the other) to the right point to release (unbond) unwanted
> ions from either end of the molecule. At least this is what I was taught
> by dear ol' Dr. T. H. James. It is a decent first approximation to a much
> more complex process.
> Soooooooo, Hypo eliminators have a bad rep and hypo clearing agents a
> good one.
> CHEERS!
> BOB KISS
>
> ----- Original Message -----
> From: Sandy King <sanking@clemson.edu>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Friday, January 25, 2002 9:37 PM
> Subject: Re: Kallitype vs. PT/PD
>
>
> > Judy Seigel wrote:
> > >
> > >
> > >
> > >I think palladium costs as much as platinum now, doesn't it, or is that
> > >just rumor?
> >
> >
> > I only use the platinum #3 solution for toning, which I think is a
> > mixture of palladium and platinum. It is fairly expensive.
> >
> >
> > >
> > >But I wonder about your mention of hypo eliminator. Last I heard (long
> > >ago, admittedly) experts said don't use that, bad for SG prints. Is that
> > >now inoperative?
> >
> >
> > What I use is a 3% sodium sulfite solution, followed by a wash of
> > about 15 minutes.The sodium sulfite does not eliminate the hypo but
> > converts it into something that does not react with the silver. Or at
> > least that is what I read somewhere by someone who should know and
> > that is why I use it. I understand that Kodak Hypo Clear is of
> > similar composition?
> >
> > Sandy
> >
> > --
> >
>
>
>
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