[alt-photo] Re: Salted paper pH
photographeur at nerdshack.com
Tue Oct 11 20:49:11 GMT 2011
>Should the paper for salted paper be pH neutral, acid or alkaline during
>the process? Alkaline buffering post-processing seems prudent, but I'm
>wondering about during salting, silvering, exposure and processing.
That depends on the particular process you use. The paper will be
close to neutral if you sensitize with a plain chloride bath and a
silver nitrate bath. However, as photographers discovered in the
1840s, one obtains better results if the salting bath has an active
organic component. This is almost always acidic (commonly citric or
tartaric acid), which will result in an acidic coating prior to
drying and exposure.
The initial post-exposure rinse should be neutral. Gold toners are
alkaline, and platinum toners are acidic (I use both, gold followed
by another rinse, then Pt). The fixer should be alkaline, and most
washing aids are also somewhat alkaline.
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