U of S | Mailing List Archive | alt-photo-process-l | Re: my pigment dilutions

Re: my pigment dilutions

See a new scan:


I have put few drops of water over half of the black patch and brushed
over this. The result is a warm gray. The rectangle on the left reads R157
G149 B128, the one on the right reads R218 G214 B200. From this, can we
draw the conclusion that I have to use less concentrated yellow? (About
1/3 less, keeping the concentration of M and C constant.)


26 Ekim 2008, Pazar, 12:50 am tarihinde, Loris Medici yazmış:
> Katharine, see below:
> 25 Ekim 2008, Cumartesi, 10:15 pm tarihinde, Katharine Thayer yazmış:
>>>> Dear All,
>>>> At this URL I posted a visual of my pigment dilutions:
>>>> http://christinaanderson.visualserver.com/Text_page.cfm?pID=2076
>>> Thanks for that, that's helpful. Will analyze more deeply (by
>>> comparing
>>> our yellows) but at first sight it seems that both of the my planned
>>> magenta and pthalo concentrations are considerably stronger (in
>>> proportion
>>> to yellow) than yours.
>> I think this may have more to do with pigment choice than
>> concentrations, Loris.   The PY 151 is a very light pigment; to my
>> mind it simply can't hold its own with most magentas and cyans and
>> for that reason I don't recommend it for tricolor but prefer yellows
>> with a little more oomph to them.
> I've just made a test (albeit a clumsy one):
> I mixed 2.5 to 3 part PY151 + 1 part PV19 Rose + 1 part PB15:3 over a
> sheet of Yupo. I didn't measure exactly, just eyeballing the squeezed out
> paint amnts. Hence the designation "clumsy", and the uncertain proportion
> of Yellow.
> See the result below:
> http://www.loris.medici.name/gum/2.5-3Y_1M_1C.jpg
> The black section above is a fully exposed and developed glossy RC print
> that I use as reference black in scanning (log 2.0 or slightly more print
> density). Below this, you can see a patch made by mixing paints. I
> averaged inside the white square and the color sampler says it's R17 G15
> B13 (L2 a1 b1 in Lab mode) relative to Dmax of a glossy RC S/G print. From
> this I understand Y > M > C; Yellow is pulling both Green and Red Up, and
> since Blue is less than Green that means Cyan is weaker than Magenta (if
> not, then Blue would be stronger than Green). Correct me if I'm wrong
> please - because all this color stuff is still new to me. Anyway, this is
> quite convincing black (both in terms of density and neutrality), would
> you agree? In the light of this, can we say PY151 can hold its own with
> PV19 Rose and PB15:3, or should I test it using a different method?
> Thanks,
> Loris.