Re: dry pigment for carbon tissue

Pollmeier Klaus (100561.2417@CompuServe.COM)
19 Oct 96 08:06:51 EDT

When Hanfstaengl still used dry pigments for their tissues they used to prepare
a dispersion in stone mills first. The pigment, together with some water,
glycerine and alcohol, was given into a rotating cylinder (the smallest ca. 1
cubic foot) with stone balls inside. These mills were running many hours or even
some days before the pigment was grounded and dispersed fine enough. Using ready
made aqaous dispersions (from BASF I believe) was a big improvement. So ask BASF
for (Colonyl?) dispersions. Should be much cheaper than expensive water colors.

Regarding the hardening in glyoxal: Thanks to Judy's info I switched from
formaldehyde to glyoxal and find it excelent. The only thing I am not yet sure
of is: how effective is it compared to the formalin? So maybe I didn't yet find
the lowest possible concentration. But to harden the final print this may not be
that important, as the relief consists of hardened gelatin allready. I only must
use it prior to the final wash because right now I do the double transfer method
with a final transfer from the plexi (which serves as an excellent temporary
support for development) to a final support paper coated with unhardened
gelatin.

Klaus Pollmeier