Re: Opacity of digital negative substrates, was Re: Gum a la Sam Wang

Somewhere along in here Sandy made an analogy to carbon printing, or
anyway dichromate exposure with gelatin. I HATE to be wrong in print, but
I have an idea that analogy doesn't hold. I don't see how you can talk
about *speed* for a gum print without the variable of pigment
concentration -- or at least some reference to that -- or at least how the
"speed" is to be figured, unless of course the referent is gum +
dichromate tone only.

Although I've done various tests on Pictorico, I haven't printed with it
enough to speak with assurance of its printing qualities (tho I still
doubt it's slower than film as seems to be the consensus here -- tho maybe
it was the black ink that blocked less UV than silver blocks, even though
it read the same on the Macbeth.???)

HOWEVER, that issue aside, how do you measure "speed" when you're adding
pigment -- say, SO MUCH pigment that the steps block up, so you only have
3 instead of 5 or 6? Would you measure by the top step? But even then
you couldn't count just the substrate, you'd still have to factor the
variable of pigment & amount of pigment.

?

J.
Received on Sun Nov 23 22:58:47 2003