Wayde Allen wrote:
>Unfortunately, the one time I tried this, I used a piece of window glass
>to which the gelatin layer decided to stick. The casting surface must be
>very clean to prevent the gelatin from sticking. The gelatin might be
>less likely to stick to the plexiglass? I'm also wondering if waxing the
>glass or plexi would help prevent sticking? Would a wax film possibly
>introduce a new problem?
Don't make the coating operation more difficult than necessary. The best
approach is to mix a gelatin % solution that will set at 68-72 F in five
minutes or less and avoid the complication of a frame to serve as a dam. I
coat tissue right to the edges without the use of any kind of dam and only
rarely does it flow off the paper.
Klaus wrote:
>When I still did single transfer, I used sodium bisulfate. However I
>noticed that the yellow stain is transferred to a brighter grey/greenish
>"fog", esp. after using a higher (3-5%) concentration of dichromate as
>sensitizer and with thick transfer papers. It just became visible at the
>edges where the tissue was. I got rid of this by "painting" the transfer
>paper with sensitizer while the sandwich was waiting for development. So
>it became grey everywhere...
>Now I develop on plexi or white plastic and then transfer to paper and
>see no need for clearing.
I clear prints developed on paper in sodium bisulfite. This solution does
exhaust and when this happens I have observed what Klaus describes above,
i.e., the yellow stain becomes green/gray (or as I recall/ green/gray/blue.
Prints developed on plexi or plastic will not of course require clearing.
I avoid bubbles in the gelatin/pigment solution by leaving the jar of
solution for 12-24 hours in a water bath. When using anything other than
ink for the I generally mix the solution in an electrical mixer at a low
setting for aboute 5 minutes, which does a wonderful job of dispersing the
pigments . Afterwards I strain the mixture (nylon panyhose works well)
into another beaker or jar and leave in the bath overnight to coat the next
day. You can mix a lot of the solution at one time and freeze part of it
for use later.
Sandy King
>
>
>- Wayde
> (wallen@boulder.nist.gov)