Hello,
Thanks for answers regarding finding the appropriate density. The
density wedge is the way to go it seems. Another question comes to my
mind: would you put process colour step wedges on the same sheet to
determine the dotgain, or in a next printing run with the same density
across the width of the sheet?
I'm asking this, because when you take the route of the density wedge
to find the appropriate density, you must put the step wedges in one
row, perpendicular to the density wedge. Say you find that zone 14 has
the best density for cyan, you then look in that particular zone for
the cyan step wedge to determine the corresponding dotgain.
But: density can vary across the sheet in the printing direction. You
risk writing down dotgain results for an area that does not have the
same density as at the bottom of the page. I recently measured M 1.54
at the bottom of a page, M 1.44 in the middle op the page where the
step wedge was, and 1.54 again at the top. Dotgain for M at the bottom
was 19%, and 17% in the middle. No big deal maybe? I realise that after
putting appropriate correction curves in the rip to compensate for
extra dotgain, a new print run is needed to verify the results.
Sorry to bother you with all this, but practical advice is hard to find.
Have a nice weekend,
Yann Bouckaert
Sagam NV
Drongen, Belgium