I'm wanting to make a portable UV exposure unit for my ImagOn plates. I was considering using a contact print frame to hold the plate and transparency together. This would be instead of a larger, heavier, and more costly vacuum frame.

Will this method work? I know contact print frames are used for solar plates and of course for photo contact printing, but there is always the issue of "light leak" with photo-polymer films if there is not good enought contact between the plate and transparency.

Best, David.

Greetings, I do not know how portable the exposure frame needs to be, but I have had good results with a homemade frame. Basically a wooden box with a hole in the side big enough to stick a vacumn hose snuggly in. The top of the box is made of masonite pegboard with a piece of flexible plastic hinged on top. It is a good idea to support the middle of the pegboard with a small piece of wood to keep it flat when the vacumn is on. The frame in the attached pictur has five pillars. You can spot them by the screws in the pegboard.

You can never get good contact without a vacuum, some areas of the plate will be tight and others won't. If you are doing fine halftones, you will get extremely unpredictable results. Coantact frames will work well for very graphic lines or text though.
Sundial, thanks for sharing your DIY vacuum frame, looks like it works great!
Jennifer