RE: wiping KM73 polymer plates

[Loris Medici <mail@loris.medici.name>]

AFAIK, you can't use in-camera "negatives" with photopolymer process
since it requires a "positive".

Probably useless info but IIRC, people are using negatives with DR
values ranging from 1.7 to 2.4 for "copper photogravure" (makes sense
since you're exposing a carbon tissue when making coppergravures -> you
can vary the tissue contrast considerably by changing dichromate
strength).

I can't say I know the photopolymer process well (only outline info) but
it seems that there are many parameters to consider (screen type and
resolution, type/brand of plate and so on...) therefore my bet would be:
it's a matter of trial and error (= no absolute DR requirements, can
vary according to one's materials and procedures...)

Regards,
Loris.

-----Original Message-----
From: Don Bryant [mailto:dsbryant@bellsouth.net] 
Sent: Thursday, February 08, 2007 8:41 AM
To: alt-photo-process-l@usask.ca
Subject: RE: wiping KM73 polymer plates


Hi Jon,

 
What a fascinating thread you guys have going.

I've noticed that so far people have mentioned digital negatives for use
with Solar Plates. But what about traditional in camera negatives? Is
there a specific density range that is desired for film work? Apologies
if this has been addressed already.

Thanks,

Don Bryant