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 Wed Oct 13 10:54:33 2004