[pure-silver] Re: Direct toners- the Viradon mystery

Bisulphate will not act as a stopbath, 10% bisulphite (or sulfite) will.

Walter

Christopher Woodhouse wrote: 
Until recently I have always used odorless sepia toners, normally
indirectly, following a short bleach. Having seen some prints of Ralph's I
thought I would try Viradon 'new' for the first time and was amazed at how
it reacted in the wash. I know all that stuff about using a Bisulphate stop
bath, but what I was wondering is it goes against everything I thought I
knew about chemistry. I always thought that chemical activity goes down with
lowered concentration. Watching through the side of my archival washer, the
print continues to get browner and browner, changing even after 20 minutes
gentle washing.

I'm intrigued, what is the mechanism that allows it to continually change
colour when the concentration must be extremely dilute? I thought for a
laugh I would put another print into extremely dilute Viradon - nothing
seems to happen. What am I missing? (polite responses only!)


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