Waterquality for dichromate sensitizers

Stefan Stecher (sstecher@linux1.rz.htw-kempten.de)
Mon, 27 Nov 1995 14:58:05 +0100 (MET)

Hi to all carbon, gum, oil, or bromoil printers!

Here a short information I saw in a work shop manual published
by the RPS: Pigment Printing Processes by T.I. Williams, MA, FRPS

Relating to discussion about fog problems on this list he wrote:

..In most photographic processes hard water gives little trouble...
..In gelatin-bichromate chemistry, however, it is a peril. Firstly
the swelling power of gelatin is reduced; secondly it affects dichromate
solutions adversely. It was noticed long ago that a bromoil bleacher made
up with hard water seemed to lose power after a week or so, with some effects
on the shadows apparently due to slow interaction between the calcium and
chromate ions giving rise to general tanning.
Also, in the carbro process, hard water in the sensitizer has the
immediately visible effect of eroding the highlights....

Does anybody know more about this and could the same happen with carbon?

Hope this information is helpfull for somebody, :-))

Stefan Stecher