[alt-photo] Re: salt prints

[etienne garbaux]

Margaret wrote:

>I am having some trouble with salt prints I made about 4 years ago, 
>some of them are starting to lose detail, for example the faces in 
>one portrait are starting to disappear, not fading exactly just loosing detail.
>Does anyone have any idea what might be causing the problem.

You do not mention whether the prints were toned.  If they were not, 
the most likely causes would be not having fully fixed the prints 
and/or not having fully washed out the fixer.  People often fix too 
little, because the fixer tends to bleach salt prints due to the 
extremely fine grains of silver produced, so prints are snatched from 
the fixer early.  Thorough washing can be very difficult, due to the 
fragility of the paper substrate (compared to silver gelatin photo paper).

Next would be atmospheric degradation and/or bleaching from exposure 
to light.  Again, because of the extremely fine grains of silver in a 
salt print (and also the lack of a protective medium such as 
gelatin), the image is very fragile.  Four years strikes me as a bit 
soon for atmospheric degradation, though, unless you live in a 
horribly polluted metropolis, so I'd be more inclined to suspect 
improper fixing and/or washing.

People who are serious about the longevity of salt prints tone them 
in Pt and/or Au (early practitioners sometimes used sulfide toning, 
and modern printers sometimes use these or Se toners), which also 
minimizes density lost in the fixer (toning is typically done before 
fixing).  Some also finish them with a gelatin or lacquer protective 
layer in the hope of delaying atmospheric degradation.

An excellent reference (Reilly's The Albumen and Salted Paper Book) 
is available on-line at:

http://albumen.conservation-us.org/library/monographs/reilly/

Best regards,

etienne