--- In PPLetterpress@yahoogroups.com, Kernow Craig <kernow@...> wrote:
> . . . I¹ve
> been offered a bottom lit vacuum exposure unit. The diffuser layer is
> adhered directly to the glass. Being bottom lit means that the polymer
> plate would lay face down on the film.
With a face-down exposure unit, you will be working blind, so a very clean working environment would be important. That is, you won't be aware if any dust, hair, or other foreign matter is in the image area until you've processed and proofed the plate. These can ruin a plate and require remakes which can become costly.
The normal face-up design, whether glass or krene over the material, lets you see that all is clean and ready to expose.
But if the unit is free or cheap, use it until a better one is available.
--Eic Holub, SF