U of S | Mailing List Archive | alt-photo-process-l | separations for gum printing

separations for gum printing





All,
This recent discussion on tricolor gum printing sparked my interest. My printing times are about the same with all colors, but perhaps I compensate with development time, these two variables are related. But that is not what I wanted to discuss. Mostly everybody agrees that B channel (in the RGB color space) intended for yellow printing always requires a different curve then RG channels. This is also my observation and practice. The B channel is almost always much 'flatter" then oher channels and requires a more pronounced curvature. Quite frequently I do not have enough definition in the B channel to get enough contrast resulting in prints with overall yellow cast.
Since CMYK space and separations are intended for printmaking, which is what we do in gum I started making CMY separations with K set to zero. There is a visual difference on how the pictures look on screen in these two color spaces (anyone interested should try to toggle between spaces in Photosop) and also how the Y separation looks compared to B channnel in RGB color space. It also seems like the colors are less muddy. I have only done a few pictures so far, but I want to see if anybody is doing different methods of generating separations for tricolor gums.
Marek 


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