Re: Making Silver Oxide From Red Devil Lye: Argyrotype

Michael wrote:

> the lye I have on hand is guaranteed 98.5 per cent pure sodium
> hydroxide, marketed as an ingredient for making soap.

> I'm thinking that this must be pure
> enough for this intended use.

Of course, it all depends on what the < 1.5% impurities are and what
process you are doing! But yes, grocery-store lye is generally perfectly
fine for all photographic uses (as are grocery-store washing soda [sodium
carbonate], baking soda [sodium bicarbonate], sour salt [citric acid], and
borax).

My previous message was directed specifically at Drano brand drain cleaner,
which (in the US) is about 90% sodium hydroxide plus about 10% aluminum
shavings plus coloring and anti-caking ingredients. It's primarily the
aluminum that makes Drano unsuitable for photographic uses. When you put
it in water, the NaOH reacts with the aluminum, giving off hydrogen gas and
leaving aluminum ions in the solution. The aluminum ions then react with
other ions in your coating and/or processing chemistry (particularly those
containing other metal ions), leading to undesired results.

Best regards,

etienne
Received on Mon Sep 5 17:09:25 2005