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Author

Date

Plotter's matcher

Robert S. Sfeir

4:57 2 Dec 03

Re: Plotter's matcher

Phil Davis

7:17 2 Dec 03

Speed Point in Pt/Pd Printing

Sandy King

9:49 8 Nov 03

I am preparing an appendix on UV light sources for a book on Pt/Pd printing and I have some questions about speed point convention that need to be addressed in my comparison of different light sources.

In silver printing the speed point is defined by ANSI standards as the exposure necessary to produce a print density of log 0.6 over B+F.

In carbon printing, where we have an almost perfectly straight and linear curve, it has been my experience that the silver convention is not the most logical way to establish the effective printing speed of different light sources and I usually find that the point on the curve that has the first maximum black, or some very high percentage of maximum black, is a better indicator.

But the pt/pd curve is of course quite different from both a silver and carbon curve, in fact somewhat intermediary between the two. So I am wondering how we should determine the speed point for for pt/pd printing? Do you think the silver printing convention is a good indicator, or would it be better to set the the point at Dmax, or at some percentage of Dmax? Or at some other point?

Any thoughts on this by Phil or other pt/pd printers would be appreciated.