Iron and conservation issues and argyrotype

As i did not receive this via the list on first time of sending, I have
revised it incorporating some other points that occurred to me subsequently.

Terry

In a message dated 27/3/06 5:49:46 pm, wcharmon@wt.net writes:

> Without knowing the exact procedure used, how
> it was checked for total clearing and so forth, it seems to be a large jump
> in
> reasoning to pin the 'browning' wholly on EDTA. Sort of the 'cum hoc ergo
> propter hoc' logical fallacy.
>
>
.
My experience is much the same. Some platinum prints suffer from iron
contamination which only becomes evident after many years.  I assume that these 'old'
prints were cleared in HcL and washed in water. This is the approach I use
myself after many years of trying other approaches including clearing in EDTA
and citric acid. Mike Ware suggested the HcL approach in one of his early
manuals, ie three 5 minute clearing baths of 1% HcL followed by a long wash in
water. It works for me.

My comments relating to EDTA arise from my own printing experience as well as
finding gold and platinum prints which had been kept in a box for many years,
which had turned brown and which, I was told  by the person who made them,
had been cleared in EDTA. There is also anecdotal evidence from students and
others including the correspondent of US Photography who attended the first APIS
in 1997, whose usual answers to questions was 'Didn't you read my article in
US Photography in  1942', who said ' EDTA never cleared anything' In other
words, the comment was not based upon one example which would have been a
logically invalid as it would have been an argument from the particular to the
general. It would not have been an example of''post hoc ergo propter hoc', this
happened after that so it must be a result of that, as has been suggested, but
  a valid inference, rather than a conclusion, drawn from experience. But as
will be seen later, there may be yet another explanation.

I have never had any difficulties with VDB prints which i find easy to print
with satisfying results that have lasted for well over twenty years with no
trace of 'browning' or foxing..(It is also significant that although Nicol got
it wrong when he 'developed' the original VDM or kallitype process, subsequent
work has made the VDB/kallitype as archival as any other silver process).
In the light of this experience, I have never made an argyrotype, the pocess
had not been discovered when I started, and have never commented on their
appearance or longevity. I have though, asked the question, why go to more trouble,
when there is a simple and effective alternative. I asked my original question
" What advantages are there in making argyrotypes" as i wanted to be aware of
the experience of others. I have had those comments and I am grateful.

It is perhaps, worth adding that Peter Marshall and I, and probably others on
the list, have made our own variations on the iron/silver processes to see
what would happen.

Michael Maunder's articles in AG are also worth consulting as he, as I have,
has gone back to Herschel's work in the 1840s, when he set out the effect and
potential of iron and other elements in the making of photographs.

It is also significant that I had some of Peter's silver gelatine prints in
the same box as the brown, but ETA cleared, gold and platinum prints. Peter's
s/g prints were as beautiful now as when he made them, he is a fine
photographer and fine craftsman, but his mounts had turned a brown of the same hue as
the EDTA cleared prints, that is the print area not the paper on which the
prints were made. This could be coincidence but one could have contaminated the
other. But was it the mounting board which contaminated the EDTA cleared prints
or the other way round. Other prints, including gum and other processes, have
not been affected by this change.

Terry

Terry
Received on Tue Mar 28 04:18:14 2006