Re: Gum Tri-Color Yellow

I've been reading this thread for several days, and there seems to be a misconception. Katherine states "three saturated primaries will give you black every time". This is not the case. Otherwise color printers (laser, ink jet, dye sub, thermal transfer, etc) would never need a black ink. In fact all computer printers, with their inks tuned by the manufacturers, to get the best colors and black they can, provide black ink, toner, ribbon, etc to give you a real black. I've been working in the printer industry for over 15 years, and I can assure you that the 3 primaries of C, M, and Y will always give you a kind of muddy brown, but never a neutral black. Depending on the primary colors themselves, you might get brownish, purplish, or other colors. Printers are CMYK devices, not CMY.

For this reason, printers (even printing presses) provide a form of "black overprint" to provide a true black.

I find it hard to believe that if you printed a 3 color print, using the same negative, simply overlaying your C, M, and Y and then did another print of the same neg, using only a pure black, say lampblack, you would not see a distinct difference.

--
Bill Leigh
wrleigh@att.net
> Another thought, and this is just musing on my part, so take it with
> salt: it occurs to me that if all formulations of PV19 are as wimpy as
> the ones I have, and this seems likely since Daniel Smith and M. Graham
> tend to be well-pigmented, then in order to get a neutral color balance
> you'd have to back off on the blue and red, and then you'd get grey
> instead of black. I've never understood why anyone would need to add
> black to a tricolor, since three saturated primaries will give you black
> every time, but this offers a hint.
> 
> And that's the real answer to Mark's question the other day about how
> you can tell color balance without using color separations. I guess it
> seemed so obvious to me that I didn't think to say it. If the color
> balance is right, the three together will produce a neutral black in the
> shadows and a neutral grey in the mid and highlights. 
> 
> BTW, and this is something I just learned, since PV19 isn't a color I've
> ever used in my work (don't ask me why I have three tubes of it) there
> are two forms of PV19: gamma and beta. It's the gamma form that gives
> the rose-red color; the beta is very definitely violet, not reddish. The
> rose-red has a distinctly violet cast to it, as I learned when I brushed
> the two versions I have of this gamma PV19 on paper just to look at them
> in comparison with each other.  When I washed the brushes out, the color
> of the wash water was violet, not rose-red at all, even though the paint
> on the brush and on the paper was rose- red. 
> Katharine