[alt-photo] Re: gold toning

[Richard Knoppow]

----- Original Message ----- 
From: "Marek Matusz" <marekmatusz at hotmail.com>
To: "alt photo" 
<alt-photo-process-list at lists.altphotolist.org>
Sent: Monday, April 26, 2010 10:40 AM
Subject: [alt-photo] Re: gold toning


>
> Chris,
>
> A few years back I went to a show of large albument prints 
> of Carleton Watkins. These prints were the original turn 
> of the century albumens. You could easily pick  gold toned 
> prints. The colour was well preserved, with no fading and 
> beautiful reddish tone. On the other hand there were some 
> prints that badly faded to brownish yellow. It seems that 
> similar observations can be made from numerous 
> reproductions of albumen prints.
>
> Albumen seems to be very suseptible to fading if not 
> toned, at least on the 100 year time frame. Gold was a 
> standard toner back then. Platinum can also be used for 
> black or grey toning.
>
> I actually naver had good luck with palladium as it 
> frequently leaves a yellow stain that I found impossible 
> to remove.  The stain is a function of paper/size, but as 
> I said, the formulas that I used were not very consistent.
>
> So my vote is toning.
>
> Gold toning is applied before fixing
>
>>From a personal perspective I made very few albumen prints 
>>way back when I was printing from in camera negatives, 
>>which now I know did not have enough density for this 
>>process.
>
> Marek

     From what I understand gold toning serves two purposes: 
in the case of POP or similar processes where the silver 
image is formed of extremely fine grain silver it prevents 
bleaching of the image by the fixing bath. Secondly, gold is 
very effective in preventing oxidation of silver images by 
peroxides and other polutants in air or polutants in the 
paper. It is effective for all types of silver images 
including conventional "silver-gelatin". Gold toning is a 
standard method for protection of microfilm. The use of a 
sulfide toner of the polysulfide type (Kodak Brown Toner is 
an example) has become a more or less standard treatment for 
microfilm in recent years because it is significantly 
cheaper than gold toner and the previously used Kodak Rapid 
Selenium Toner was found to be inadequatly effective when 
used in the originally recommended high dilution (1:19) and 
in higher dilutions has too much effect on image structure 
for use on microfilm.
     Both polysulfide and KRST will tone undeveloped silver 
halide as effectively as metallic silver so are not useful 
in pre-fix toning plus KRST has a significant amount of 
ammonium thiosulfate in it which will cause fading of the 
unfixed image. I am not sure if this is a factor for salt 
and albumin prints but think it probably is.

--
Richard Knoppow
Los Angeles, CA, USA
dickburk at ix.netcom.com