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Re: Hypo Eliminators
Thanks, Sil, you're really an asset to the list, with your strong chemistry
background.
Joe Arkins
Sil Horwitz wrote:
> At 2000/03/26 02:51 PM -0500, Joe Arkins wrote:
> >Does this mean a sodium carbonate (10%) solution used as a washing aid for
> >pyro
> >negatives should not be used, because of potential harm to the image and/or
> >gelatine.
>
> Sodium carbonate is NOT "caustic soda" and has a much lower pH than the
> hydroxide. A 10% solution will not harm gelatin during short immersions,
> but you will get a safer effect with the Kodak wash accellerator, which is
> a buffered sulfite solution plus additives.
>
> >If so, is it possible to buffer a sodium carbonate solution to avert this
> >harm,
> >and if so, what would be a suitable compound with which to do so?
>
> Yes, you could buffer the carbonate, but there would be no point, as you
> will be reducing the alkalinity, and the sulfite solutions for the purpose
> are better. That's why Kodak uses sulfite. Sulfite is the photographer's
> universal reagent!
>
> Sil Horwitz, FPSA
> Technical Editor, PSA Journal
> teched@psa-photo.org
> silh@earthlink.net
> Visit http://www.psa-photo.org/
> Personal page: http://home.earthlink.net/~silh/