I assume if I increased
exposure times by 25% with the KM73 I'd have blown out highlights. Based on your notes, I'm assuming here that the ratio shifts by some factor as the exposure times increase or decrease. I'm wondering if you have some data on what that factor might be (yes, I'm being lazy).
Also, how do Elizabeth Dove's screens differ from Dan Welden's? Do they use a different pattern? More or less coarse? Thicker plastic?Dove's are MUCH thicker plastic, much sturdier, and under a loupe it is the same pattern as Dan's but coarser. However, Dan's has a noticeable line pattern running through it, like it was printed on a computer or something...which Dove's does not.
Yes, my theory is the ratio shifts with different exposure times--made apparent to me by the 4x positive to 1x aquatint in Ponsaing's book. Don't have R and D for you at this time, so can't save you any blood sweat and tears, but you can be sure I will let you know when all is said and done. One thing I will say about solarplate/photopolymer--I can't "assume" anything because it usually is the opposite of what I assume. But at least I have solved 1) why such a variance in exposure and 2) the ratio is what is important, thanks to reading between the lines in Longely, Welden and Ponsaing's books, and then applying that knowledge to PDN. If I had my own press I could do all this testing in 1/10th the time...