Re: Mylar as base for carbon tissue

Pollmeier Klaus (100561.2417@CompuServe.COM)
21 Apr 96 18:47:24 EDT

When we developed the color carbon tissues at Hanfstaengl's in 1992, we tested
two subbing layers for the polyester film. (Without subbing layer, the emulsions
were lifting off too easily). One they called *micro wax coating*, but didn't
tell me exactly what it consisted of. Probably some kind of wax in a solvent.
This coating should ensure temporary adhesion of the pigmented gelatin and
enable us to peel off the backing prior to development - to make development
easier, faster and more even. But it turned out that even with this subbing
layer, the emulsions came off the polyetser during drying. The other layer,
which prooved to be better, was some kind of artificial coutchouc (again I know
no details). With this layer the gelatin sticked to the polyester even if we
didn't use any glycerine in the sensitizer.

A proposal: If you don't need a clear and perfect back (in the case you do not
expose from behind, although by doing so you could avoid the transfer), just
sand down the side to be coated or give it a thin coating of collodion (or PVA?)
before you apply the warm gelatin.

Klaus Pollmeier