I posted some at least of the results of the little ageing test here a year or
so ago, so it will be in the archive. The process samples were rated on the
'blue wool scale' after a fairly lengthy exposure to UV.
<<
Washing out the fixer too well causes mould growth? Never heard tell of
that! I would blame it on dampness. Kodak and others used to have
publications for processing in damp climates. One solution would be to keep
your collection in one area where you can have a small but effective
dehumidifier running through the damp period of the year. >>
It is now apparently generally recognised that a small residual of
thiosulphate helps in the storage of silver gelatin prints. I think both Kodak
and Fuji research has confirmed the desirability of low levels - low, but well
above those that can be achieved by extended washing.
However when I say 'I was told' in relation to mould growth I meant just that
- not necessarily that I believed it. Some chemicals in the gelatin will
certainly inhibit growth of various moulds but I have no firm evidence that
thiosulphate is one of them. It simply amuses me slightly.
In normal years our wet season lasts 12 months, though it has been in short
supply recently. I think it is probably quite a good thing that my prints are
somewhat transient in any case!
The gelatin that remains on carbon prints has been very effectively hardened
as a part of the process which probably makes it less friendly to mould. I've
not seen it on carbons (yet).
Do you have any ideas about the cause of the red stain on the platinums? Can
it be removed by suitable treatment - perhaps edta? If I had it on any of mine
I'd give it a try but of course great care is needed with material of
historical value.
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/