Re: Old Postcard Silver Patina

Tom,

The strong silver mirroring one of the
symptoms what help to identify the silver-
gelatin developing out papers. Mainly the old
ones which has not an extra hard gelatine
protective layer on the surface (for hot drying).

In the pinting out papers (like the albumen) the
size of grains much smaller (it is also a help at
the identification to make different between the
POP and DOP papers). So the much less
amount of silver is not enough to make a
strong, visible mirroring silver layer. Anyway
the degradation process is working in the POP
papers also but the visible result usually the
fading, yellowing.

Bálint.
Budapest, Hungary

http://archfoto.atspace.com/

Date sent: Sat, 07 Jan 2006 11:19:23 +0100
From: Tom Sobota <tsobota@teleline.es>
Subject: Re: Old Postcard Silver Patina
To: alt-photo-process-l@sask.usask.ca
Send reply to: alt-photo-process-l@sask.usask.ca

>
> But I have never seen it on albumin positives. Or perhaps
> I just missed it, I don't know ... Could it be that the bond
> between the silver grains and albumin is stronger and
> doesn't allow migration?
>>
Received on Sat Jan 7 11:24:03 2006