FW: An exchange with Mike Ware (on Argyrotype)

Thanks Mike. Will seach for test methods in the internet. Hope to be
able this test in the future. Will certainly let you know the objective
results.

I don't exactly understand your last sentence; you say you don't see a
reason why properly processed - for instance, just as I described before
- Vandykes (or Kallitypes) shouldn't be as stable as Argyrotypes, then
you also say "but how stable that is, remains". Are you referring to the
stability of colloidal silver in general or are you hinting that
Argyrotype may still have the edge. If the latter, why? (This goes back
to one of my guesses / speculations in my original question to you:
since there's any silver nitrate dissolving effect over elemental
silver, the particles may be slightly bigger in Argyrotype when compared
to Vandyke - therefore exhibiting less surface area to pollutants /
oxidisers... On the other hand; since you said silver nitrate does so in
acidic environment, Kallitype - which is developed in alkali environment
- remains protected from silver nitrate's effect over elemental silver.)

Best regards,
Loris.

-----Original Message-----
From: Mike Ware [mailto:mike@mikeware.co.uk]
Sent: 23 Mart 2006 Perşembe 12:43
To: Loris Medici
Subject: Re: An exchange with Mike Ware (on Argyrotype)

On 23-03-06 09:12, Loris Medici wrote

> Maybe you can describe me a method for testing that so that we can all
> know if iron is left in paper even after clearing with citric acid.
> Testing for thiosulfate also is possible and easy. I can make both of
> these tests on some of my Vandykes.

When I was developing argyrotype, I was able to have the removal of iron
confirmed by X-ray fluorescence spectrometry (XRF) at a National Museum.
However, I appreciate that not everyone has access to that facility!
There are a number of colour spot tests for iron(III) in the chemistry
textbooks: ferrocyanide, thiocyanate, and Tiron (a proprietary reagent),
for instance. Feigl's 'Spot-tests' is a good source, or Vogel's
'Textbook of Qualitative Chemical Analysis'.

> If I can't find either thiosulfate or iron in the paper, can we draw
> the conclusion that if properly processed (leaving no residual
> thiosulfate and iron in paper), Vandykes (or Kallitypes) should be as
> stable as Argryrotypes?

Certainly, I can see no reason why not. But just how stable that is,
remains an open question.

Best wishes,

Mike
Received on Thu Mar 23 05:05:53 2006