[pure-silver] Re: Chemical subsitution
- From: Eric Nelson <emanmb@xxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 26 Apr 2007 22:52:11 -0700 (PDT)
Thanks Steve & Jurgen.
I had only somewhat confirmed on the Tech Chem site
(http://tinyurl.com/296j62) by their listing there, so
I wanted to get independent confirmation.
Eric
--- jswitalski@xxxxxxxxxxxxxxxx wrote:
> In solution they are the same thing. I believe that
> you can use about the
> same mass of either compound.
>
> Jurgen
>
>
> On Thu, 26 Apr 2007 18:25:43 -0700 (PDT), Eric
> Nelson wrote
> > I have discovered that I am out of sodium
> bisulfite
> > and need to make some HCA tonight for prints I
> just
> > finished.
> > I have tons of sodium metabisulfite and have
> looked
> > through the archives to see if this compound is
> > specifically addressed as an AKA or substitute
> > compound for sodium bisulfite.
> > I've included some quotes below of Richard's that
> seem
> > to answer this question, so I'm wondering if there
> is
> > a definitive answer out there as to whether I can
> use
> > metabisulfite in place of bisulfite gram for gram
> in
> > the HCA formula or at what ratio it would need to
> be
> > at.
> >
> > I'm a cook not a chef so molar aspects of these
> > compounds and the Avogadro's number will go over
> my
> > head. ;-)
> > And what the heck is bisulfite lye? Found that
> > mentioned in one of my search results.
> > Eric
> >
> > "Long ago there was a discussion of what exactly
> was
> > meant
> > by sodium bisulfite in Kodak and other formulas.
> It
> > appears
> > that the compound is actually metabisulfite, or
> mostly
> > so.
> > Sodium metabisulfite is much less expensive than
> real
> > sodium
> > sulfite and is certainly suitable for this
> formula."
> >
> > ."various MSDS list either Sodium Bisulfite or
> > > Sodium Metabisulfite.
> > > > Kodak
> > > > Sodium Bisulfite appears to be mostly the
> > > metabisulfite. Evidently it
> > > > does
> > > > not matter which is used.
> > > > Because the formula is not published the
> amount of
> > > EDTA and Citrate are
> > > > not
> > > > firmly established. The MSDS for the
> concentrate
> > > (powder) lists the
> > > > amount
> > > > of either as 1 to 5% by weight. It disappears
> from
> > > the working solution.
> > > > It's possible the amount in the stock should
> be
> > > only 1 gram of each but I
> > > > think from Haist or somewhere I got the idea
> that
> > > it should be more.
> > > > Perhaps a compromise of 2 grams each should be
> > > used.
> > > > I think 15 grams of the
> bisulfite/metabisulfite is
> > > correct. In any case
> > > > the
> > > > target pH is 7.0"
> >
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