>
> It is my opinion that most, if not virtually all of us, wash alt-photo
prints far far to long.
>
>
> This comes from A. Adams, Minor White, et al. We all learned our chops
printing silver bromide and this the catechism is: wash wash wash.
>
>
> Why? Because of three things: silver, sulfur, and gelatin. Sulfur attacks
silver. Gelatin traps sulfur.
>
>
> Sulfur compounds are very large molecules. Gelatin is a big huge stringy
molecule. Washing sulfur out of gelatin is like washing ball bearings out of
steel wool. It takes lots of washing
>
>
> Most non-silver alt-photo processes do not have these three elements and in
my mind can be washed in 5 to 10 minutes and probably even less. I believe
that extended washing will degrade the image quality of noble metal process
prints, though this is surmised from theory, not empirical observation.
>
>
> Comments please.
>
>
> Dick Sullivan
>
Dick
I think alt-processes are a pretty varied bunch, so I'd be surprised if any
one statement covered them all.
However I think the problem with silver prints is NOT washing stuff out of the
gelatin. RC prints - where this is all that is happening - will wash in 2
minutes. It is the paper fibres that hold more tenaciously to the silver
complexes and thiosulphate.
Also i think it important to look at the quality of the wash as much as the
time - the number of complete changes of water. Of course this has to remain
in contact with the paper for long enough to get somewhere near equilibrium
between absorbed substances and those in solution.
Also pH of wash water is going to be important - if your water is alkaline it
may never wash out a kallitype properly.
However I suspect all things considered, 30 mins to an hour is not going to be
far from a rough all-round suitable figure - after all that is probably what
most of us have used for a while and it seems to work!
Peter Marshall
On Fixing Shadows and elsewhere:
http://faraday.clas.virginia.edu/~ds8s/
Family Pictures, German Indications, London demonstrations &
The Buildings of London etc: http://www.spelthorne.ac.uk/pm/