lars_h_gglund

Struan, Any inert powder pigment could be used, says the book. I´ve

also found a part in the book about carbon prints on porcelain. I will

send a scan to you personally.

Lars

"THE POWDER PROCESS

<p>

This process is based on the facts that colloids lose their tackiness

on exposure to light in contact with a bicromate. It is rarely used

for paper prints, and its chief application has been for the

preparation of reversed and duplicate negatives for photomechanical

work, or for making ceramic enamels. For the latter process the image

was produced on collodionized glass, to facilitate stripping, and the

image transfered to the enamel plaques."

<p>

From "Photographic facts and formulas" by Wall and Jordan Revised by

Carrol.

<p>

You can also find the formulas for this process in the book

<p>

Lars

Matt, reciprocity also have an effect on the negative contrast.

Because the shadows on the negative are hit by light of less intensity

than the highlights, they are more affected by reciprocity failure.

Thats why the contrast of the neg increase, and we need to shorten dev

time to compensate

Try this site http://ourworld.compuserve.com/homepages/Staffan_Johansson/sharp.htm

Lars