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

On Sunday 26 June 2005 04:56, 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!)

        I'm guessing fibre paper. How much toner is in the paper at this point? 
At 
some point the paper would just get totally soaked in toner and the dilution 
of the wash water isn't an issue. The dilution in the paper itself would be 
the thing. That's my guess.

        Nick
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