Regarding KM73s and polymer photogravure: Keith's method of drying the transparency for 20-30 minutes on low heat,followed by dusting both it and the plate with baby powder, the doing 3 minute drawdown prior to exposing the image prevented the patches from showing up. Tones were smooth and perfectly gradated. This is not trivial to me. This problem has plagued me since about 2004. When and how did you decide to dry your OHP transparencies in a plate drier for that long, Keith? Whatever the reason, I'm ecstatic!
Likewise, Keith's method of drying the polymer plate for 5-10 minutes under the heat of a hairdryer after washout and before post-exposure got rid of the problems I have been having with scratches. I even used tarlatan that had crusty ink on it from over a year ago, vigorously scrubbing the plate trying to mar it. It remained tough as nails.
Who'd have thought we'd need to dry ANYTHING in Colorado, but that's clearly the solution. I stopped using the hair drier after washout when an instructor in the process told me it was unnecessary. Clearly he was quite wrong and heat is critical to the curing of the plate and that post-exposure is only part of it. When I think of all the unnecessary hours of bulb use I wasted on my Olec unit trying to mitigate the problem of scratches, I cringe.
Moving ahead, this fills in two serious, long-standing, quality issues I've had using the KM73s, in spite of all their advantages. So much advice from so many people it's difficult to know exactly how I wound up doing what I have been to process plates, but my on-line procedure is due for a critical overhaul. I'm so excited. I can use tarlatan again! Smooth tones again without worry! That's not the half of it.
I'll let you know when my procedure has been revised and will ask for comments and feedback at that time. Keith I'm so very grateful you can not imagine. Send me your mailing address off-line. I want to send some goodies your way as a thank you. I wish it could be a case of KM73s, but after I make my first million dollars making intaglio plates and prints, expect a delivery of that too!
Thank you all so much for engaging in this discussion.