Re: Mylar as carbon tissue support

s carl king (sanking@hubcap.clemson.edu)
Thu, 25 Jan 1996 20:41:50 -0500 (EST)

> Well it happened to me as well but only with heavyly pigmented emulsions.
> Using large amounts of pigment caused fogging problems and poor high lights
> so I reduced the amount of pigment to the absolutely minimum, necessary
>
Although I work mostly in the traditional way and prefer paper as
the base for most of my work in carbon and carbro, I recognize that
the use of a polyester base such as Mylar offers several advantages.
I have used Mylar on several occassions in the past without experiencing
the problem you describe, i.e., the tissue sticking to the carrier during
warm water development.

I suspect that what has happened is this. In reducing
the pigment to an absolute minimum to avoid fogging problems you created
another problem, namely the light during exposure is penetrating all the
way through the tissue to the base, and those areas resist separation
during warm water development. The problem is this. When you use the
*bare* mimimum of pigment to get good blacks the line between adequate
exposure and too much (which causes the sticking problem) is a very'
precarious one.

Your logic that this is caused by the water not being
able to penetrate through the plastic to the gelatin, and Peter Charles
suggestion that you solve this problem with tiny perforations, both miss
the real point, that is, the tissue simply received too much exposure
for its specific opacity.

Sandy King
Sanking@hubcap.clemson.edu