Re: Sodium Bisulfite

According to the Merck Index, tenth edition, "The bisulfite of commerce
consists chiefly of sodium metabisulfite, Na2S2O3 (all numbers should be
read as subscripts), and for all practical purposes possesses the same
properties as the true bisulfite."
The formula for metabisulfite is NaHSO3. One metabisulfite, plus one water
equal two bisulfites. I think it rearranges when it is dissolved, kind of
like dissolving chlorine gas into water gives hypochlorous acid (HClO).
----- Original Message -----
From: "Christina Z. Anderson" <zphoto@bellsouth.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, August 25, 2004 5:48 PM
Subject: Re: Sodium Bisulfite

> Katharine, Giovanni, Kate, etc.,
>
> Now that I am not in a rush to prepare for class and can think
> concisely, I'll reiterate my points:
>
> Giovanni asked if you could use sodium sulfite. I said yes. I qualified
> that with a caveat for longer wash times. (Nadeau, BTW, says p 40 that sod
> *bi* requires at least a half hour wash time--nothing about washtime with
> pot metabi, but he says p. 25 that sod "metabi" is less odorous.)
>
> I said in my post, "Henney first to say pot metabi more effective than
alum
> or sod bi in 1939--**no mention of the wash
> time**" so Henney does not fit your qualification for a reliable wash time
> source either. It looks like Scopick is the one; you may have to email
> Scopick and find his source, and you are absolutely right on the Crawford
> citation. Crawford is not guilty of saying pot metabi washes out quicker.
> My bad. (BTW, I'm surprised you say you haven't studied Scopick, as I
> remember a long convo about his book with you...)
>
> I said "Sod bi and alum were actually the clears of choice, alum the most,
> until the 70's until its archivalness was questioned." Let me add exact
> data here, and offer an opinion (not fact). Here is the fact part: in 36
> sources I have quotes from on clearing, 27 mentions of alum, 15 sodium
> bisulfite, 3 sodium bisulfate, 3 sodium hyposulfite (now thiosulfate), 3
> sodium sulfite, 14 pot metabisulfite, 3 sodium metabisulfite, and one
> potassium bisulfite. Now I hope I have my "ates" and "ites" correct--and
my
> "ph" and "f". Chemists can explain what the differences are between pots
and
> sods and metabi, bi, ites and ates.
>
> One of the reasons I put my notes in chronological order is to see the
> change in the process over time, and to try to see where a thread of an
idea
> starts and is continued. There is a shift from the alum and sulfite to pot
> metabi thru the years, just like there was a shift from pot di to am di
over
> the years (a whole 'nother story).
>
> Anyway, opinion here: the fact that one or another was preferred could
have
> more to do with availability, price, convenience, or some other factor
than
> performance. Alum is called into archival question only as of late, even
> tho in the old lit it was also said to create grain and shrink the paper
and
> take a long time to clear the di stain out--even when it was the drug of
> choice.
>
> Giovanni or Kate, this is why people didn't clear until the last multiple
> coat was put on, usually--paper registration as well as gum softening;
> perhaps the paper shrinkage had nothing to do with alum but they thought
it
> did. We have to think back to the time before multiple coats occurred
> regularly--coats were thick and juicy and exposed lightly, so to
immediately
> put a fresh gum into a clear was sketchy. Once dried it was more stable.
> But one of the fascinating things I found in research was they thought
> multiple coats weren't possible--that the next gum coat would soften the
one
> below. Now we're the smarter.
>
> To me, gum is a practice more than a science, and if there is a hint that
> some clears require longer wash times, they are (unscientifically) guilty
> until proven innocent in my book. But whichever sulfite/ate wins the
race
> to leach out into the wash water the quickest is for a chemist to answer,
> or maybe Getty would take on this task, scanning for residual chems in
test
> gum prints cleared with different clears and times of clearing.
>
> And, as far as clears go, in the olden days people didn't clear if they
> didn't SEE the need to, so, so much for having to clear in the first place
> for archival reasons.
>
> I think I've "cleared" enough.
> Chris
> PS Katharine, I read your article in Lenswork and LOVED it. Here's to
> post-postmodernism--something my thesis is going to touch on. I'm going to
> quote you, and I'll even cite you correctly.
>
> ----- Original Message -----
> From: "Katharine Thayer" <kthayer@pacifier.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Wednesday, August 25, 2004 7:06 AM
> Subject: Re: Sodium Bisulfite
>
>
> > Christina Z. Anderson wrote:
> > >
> > > Katharine,
> > > The chemists in the group can answer your question better than
I,
> so
> > > y'all have at it.
> >
> > > The necessity for a longer wash is in the lit since 1898 (Packham
> in
> > > Barnet's book). Warren recommends hypo with a long wash (1898,
Handbook
> to
> > > the Gum Process). Maskell says sod bi is extremely soluble so wash a
> minute
> > > or two (one refute). Sod bi and alum were actually the clears of
choice,
> > > alum the most, until the 70's until its archivalness was questioned.
Or
> the
> > > sun, as we have talked about here a year ago. Henney first to say pot
> > > metabi more effective than alum or sod bi in 1939--no mention of the
> wash
> > > time. Scopick says this p. 42 and and sources Wm Crawford.
> >
> >
> > Hi Chris,
> > Actually, Scopick cites Crawford for the assertion that chrome alum
> > "threatens image permanence," not for the assertion that potassium
> > metabisulfite is more soluble than sodium bisulfite and therefore
> > doesn't require such a long wash time; that latter assertion is made
> > with no citation to sources.
> >
> > Crawford was my bible when I was teaching myself gum printing, and I was
> > thinking that if this assertion was in there and I never noticed it in
> > all my poring over that book, then I'd have to eat crow over my
> > assertion that I'd never seen this idea before. (I have Scopick in my
> > library but have never spent much time studying it because I discovered
> > it long after I'd perfected my own gum process.) So I had to look up
> > Crawford to see if I was wrong, but thank goodness, I'm in the clear on
> > this one. Crawford does indeed say "Alum is often mistakenly
> > recommended but should not be used because it threatens image
> > permanence" exactly as cited and quoted by Scopick, but Crawford is not
> > responsible for the assertion about the relative solubility and wash
> > times of sodium bisulfite vs. potassium metabisulfite; he simply says
> > you can use either: "You can clear the print in a 5% solution of
> > potassum metabisulfite or sodium bisulfite." Nothing more.
> >
> > Whether
> > > all these authors are repeating misinformation or not, who knows.
> >
> > Well, I only see two in the above mini- lit review that actually make
> > the assertion about the relative solubility and required wash times of
> > the two: Henney and Scopick (ignoring the mistaken citation to
> > Crawford). Scopick (I don't have Henney so can't comment on that)
> > offers no reference or experimental findings to back up the assertion.
> > And if it's a fact as you say that sodium bisulfite was the favorite
> > next to alum until the 70s, the assertion must not have carried much
> > weight among practitioners of the time.
> >
> > I wonder what the percentage is that use one or the other today.
> >
> >
> > <snip>
> > All I know is I use pot metabi
> > > because I feel confident that a 10 min wash is sufficient therefore.
If
> I
> > > clear.
> >
> > Well, I guess I need more, some experimental data that show this
> > clearly, before I feel at all confident that there's a meaningful
> > difference between the two in terms of practice. As I say, I need to
> > clear so seldom that it's not much of an issue for me, but it sparks my
> > intellectual curiosity.
> >
> > Katharine
> >
>
>
Received on Wed Aug 25 20:00:02 2004