Re: Merits and Demerits of Salted vs. VDB

[Sandy King <sanking@clemson.edu>]

At 9:16 AM -0600 9/1/07, Christina Z. Anderson wrote:
> However, in my packet of step wedges and test prints and tonal 
> palettes printed in both, I notice that there is a fading and 
> yellowing and mottling in the VDB packet I do not see in salt. The 
> salt prints look exactly like they did the day I made them.  In the 
> troubleshooting section of my VDB chapter (Alt Proc Condensed) I 
> have a quote from Mike Ware via Wynn White: "Most sources state that 
> Vandyke prints can be cleared in plain water.  In Mike Ware's 
> description of the argyrotype process he explains the problems 
> iron-based silver processes have.  If processed in an alkaline 
> solution residual ferric iron is left in the print which will 
> eventually cause it to fade since iron (III) will oxidize silver."
>
>
> Chris

There are two important steps that if carried out will dramatically 
improve the quality of VDB prints. The first is to make absolutely 
sure that the first wash is carried out in water that is slightly 
acidic. If the water is alkaline iron hydroxide will be set in the 
paper and this can can be removed in subsequent processing. However, 
don't make the first bath too acidic because it might bleach the 
silver.

Second, bite the money bullet and buy some noble metal solution 
(gold, pallaidum or platinum) and tone the print before fixing. This 
will eliminate bleaching and give you the deepest possible shadow 
values.

Sandy King