Re: Sodium Bisulfite

Giovanni Di Mase wrote:
>
> Thanks Katharine for letting us know.
> Honestly, I took the word of Photoformulary as real and didn't have the time
> to test it as you did.
> What Alberto was mentioning to you is that there are two color stains, the
> "dichromate stain" and the "chromium stain" and apparently the sodium
> sulfite does not work on the last one.

Hmm, that's interesting. I didn't see Alberto saying that, and as far as
I know, that distinction came from me; I tried to introduce that
distinction several years ago and got nowhere with it and gave it up. If
he means "dichromate stain" to mean a bright yellow stain that is made
almost entirely of dichromate, (a rare kind of stain that I've only
seen with certain paper/size combinations or when a drop of dichromate
was spilled and got picked up by the back of the paper) and a "chromium"
stain to mean a brown stain that is something else, then I disagree with
the above statement, because it was the brown stain that the sulfite
dissolved.

> Something else that Alberto mentioned to me is that he doesn't use and
> clearing agent but leaves the print on just water the whole night and he
> said it works better for clearing purposes.

Well then what he got isn't actually a stain. A stain is something that
won't dissolve in the water bath and needs more aggressive treatment.

> Regards,
> Giovanni
>
> ----- Original Message -----
> From: "Katharine Thayer" <kthayer@pacifier.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Wednesday, October 13, 2004 5:56 AM
> Subject: Re: Sodium Bisulfite
>
> > Katharine Thayer wrote:
> > >
> > > Giovanni Di Mase wrote:
> > > >
> > > > There is also sodium sulfite that works as sodium bisulfite according
> to
> > > > James book.
> > > > But I was told that the sulfite does not create the solution acid and
> > > > therefore the cromium component becomes insoluble cromium.
> > > > What does this mean in terms of stains I don't know.
> > > > Can anybody help?
> > >
> > > Giovanni,
> > > I'd say, given the contradictory information you've been given, that the
> > > best way to find out how sulfite compares to the others is to try it
> > > yourself, side by side with sodium bisulfite or potassium metabisulfite,
> > > and see what happens.
> >
> > Hi Giovanni,
> > Just out of curiosity I did this comparison myself. I was going to show
> > the results, but my scanner is scanning too red and in trying to fix it
> > I'm not getting the results the right color and tone to accurately
> > reflect the originals, especially to show a very very faint blue-grey
> > tone accurately. Since I don't have any more time to spend on it, I'll
> > just have to describe the experiment and results:
> >
> > I deliberately made a dichromate stain by coating paper (Fabriano Uno)
> > with unpigmented dichromated gum, setting it in the sun for five
> > minutes, then developing and drying it. The stain was tan-brown, the
> > usual dichromate stain color. I cut the paper in half and put half in 5%
> > potassium metabisulfite and half in 5% sodium sulfite. The half in
> > potassium metabisulfite cleared in 5 minutes. The half in sodium sulfite
> > also cleared completely, but took longer. After an hour, the tan-brown
> > was completely cleared, but there was still a grey tone that I didn't
> > like, so I left it overnight. This morning it was pristine white in the
> > bath. Both of the cleared stains looked paper- white when wet, but on
> > drying took on a slight bluish grey tone, very faint. The two halves of
> > the cleared stain look so exactly the same color and tone that they look
> > as if the paper had been cut after clearing rather than before; there is
> > simply no discernable difference between the two halves of the stain.
> >
> > So I guess my answer to Giovanni's question is yes, sulfite works the
> > same, but takes a bit longer. I'm wondering if it could be speeded up by
> > increasing the concentration, but I don't have time to test that today.
> >
Received on Fri Oct 15 10:19:57 2004