Re: I stand corrected

[Clay <wcharmon@wt.net>]

And to answer your question, there is no doubt you can get extremely  
dense negatives from combining colors. For instance, a 60% yellow and  
60% cyan mix yield predicted densities of 2.4 and .92 individually on  
my 7800. Combining the two into a green color will get you a predicted  
density of 3.32. This is very close to what I actually see. The only  
joker in the deck here is the total ink percentage. You can see that  
the above example loads a120% ink load onto the film. This is  
dangerously large. I like to keep the total ink % in the 60-90% range.  
Which means that lower percentages of denser inks is the way to go.
On Apr 13, 2009, at 6:30 AM, Loris Medici wrote:

> I inspected the UV transmission density charts Clay kindly shared,  
> and I
> have to correct myself:
>
> Whereas yellow is the densest of all inks - which was one of my  
> points,
> this doesn't necessarily mean that it's even denser than combination
> colors (such as Y+C -> Green). This is proven by the fact that with  
> Epson
> 2400 yellow ink gives log 2.47 UV density by itself (according to  
> Clay's
> datasheet) whereas I'm pretty sure there are persons using this  
> printer
> for processes that require more DR than log 2.47. That proves my  
> second
> point (about printer ink limits and yellow being denser than green)  
> wrong!
> (So many CDRP tests with so many different processes - especially  
> low ER
> processes such as Cyanotype and Gum - got me confused; sorry for the
> inconvenience.)
>
> Regards,
> Loris.