> . . .
> It is puzzling why Fresson whould spin coat as it seems to be a piecemeal
> approach when roller "kiss" coating would make more sense. I fail to see
> what the advantage would be to them, though there very well may be one.
>
Richard,
At least with my DP3 Process, coating eveness is CRITICAL to image
quality. Any flaws in the coating (ie - runs, ripples) wind up in the
finished image . . . think about the physical abrasion development.
Spraying can apply very very thin coats, I build up the needed layer
thickness through multiple thin spray coats as you saw in my slides at
APIS. In addition I re-heat the coating to raise it above its gelation
temperature and flow the coating while the sheet is horizontal . . . again
aimed at achieving an even and flat coating layer.
The manner in which one sprays I seriously doubt matters. Spin coating
versus current compressed air spraying . . . who cares (though I would
guess that spin coating is more energy efficient but probably wastes a lot
of the fluid being sprayed).
Also . . . though I didn't have time to explain at APIS, I have coated
using alternate methods and produced very good quality DP3 prints. It
just wasn't very efficient nor would it lend itself to multiple layers
needed for full color work.
Roll coating works very well with a continuous web of material, but not
cut sheets. Now think about doing color where each print it coated,
exposed and developed four times . . . the coating of sheets is the
target.
Sincerely, Art
Art Chakalis
Columbus, Ohio, USA