Terry,

You can also try making 1:5 top and bottom portions and half baking
(15min cure at 70-80=B0C) a 1:20 layer between as a glue layer.  This =
can be applied via spin coating, although if you don't have one
available, you can also lightly smear it on with something that has a
reasonably straight edge - e.g. a coverslip, slide, or even a piece of
office grade overhead transparency.

Lee Pang
[email protected]