Re: bichromate gum

[sam wang <stwang@clemson.edu>]

Don,

That's actually a good way to control brush stroke patterns - take  
your time coating with just the dichromate first, and then the gum  
with pigment. This is especially useful in spray or airbrush coating  
of gum, so that the end result will still have the brush markings and  
you don't have to worry about breathing in the dichromate.

I suspect that the higher contrast is due to the reduced amount of  
dichromate, which would be a good thing to practice but you will need  
to test and make a curve to fit that.

As Judy would suggest, start with printing a step tablet and that  
should tell you a lot.

Sam

On Jul 7, 2008, at 5:53 PM, Don Sweet wrote:

> Christopher James' new book mentions, as an untested idea, something  
> that I
> read recently in a Barnet text from about 1898, namely that you can  
> put the
> dichromate coat on after the size has hardened and leave the paper  
> for some
> time before putting the paint/gum coat.  From memory the Barnet text  
> (too
> dear to buy) suggested the resulting image would be more contrasty  
> with less
> highlight details than a conventional gum print.  Can anyone cast any
> further light on this idea, or suggest any starting points for further
> experimentation?
> Thanks
> Don Sweet