Re: Pigments for neutral color balance in gum: (Re: Fish Eyes again)
Loris, the starting "colors" you use are important for sure but the proper color separations may prove more significative in obtaining neutral print values. But you will need special tools and software to do this but it will also take the guess work out of the process. I would argue that this problem is one of the many reason color management was design for. To my knowledge, there is even a special algorithm design for this specific problem, if memory serve me well I think it is called the gray axis algorithm. Combine this with a software program that can create the required separations and you should be in business. Hope this helps, Yves ----- Original Message ----- From: "Loris Medici" <mail@loris.medici.name> To: <alt-photo-process-l@usask.ca> Sent: Thursday, September 18, 2008 6:59 AM Subject: Re: Pigments for neutral color balance in gum: (Re: Fish Eyes again) > Thanks Katharine. Before dismissing PV19, I will first try using PB15:3 as > the blue. Since the spacing between PY42/43 and PV19 is fine (albeit in > the opposite direction of what McEvoy suggests; a yellow closer to the > magenta instead of a magenta closer to the yellow), and PB15:3 is right > opposite to them. If that doesn't give me acceptable results, then will > try with a brighter / colder yellow and a redder magenta. For the moment I > like PY42/43 because if gives nice / contrasty gradation gradations unlike > the brighter yellows (I simply can't see the gradations when printing with > a bright / transparent yellow). > > Regards, > Loris. > > > 17 Eylül 2008, Çarşamba, 5:38 pm tarihinde, Katharine Thayer yazmış: > > Hi Loris, sorry about taking off on a tangent. I'm just guessing > > here, because I've not used that yellow (and would recommend using > > handprint's mixing triangle as an initial screen, as I suggest on my > > tricolor page) but I would definitely suggest a less blue magenta > > with your combination. I've had good results with PR 175, a deep > > scarlet, with ultramarine and PY110, and Marek recently reported > > doing well with perylene maroon (PR179)-- which has a very similar > > hue to PR175-- with PY 150, which is also kind of an off-the-beaten- > > path yellow, and indanthrone, which like ultramarine, has more red in > > it than a true cyan. > > > > It's a casual observation (I haven't done a careful study of this) > > that PV 19 is more likely to be implicated in those ugly purplish > > brown "neutrals" than other pigments; I use it only with yellows and > > blues that stay pretty close to the pure primary hue. Since the > > ultramarine is redder than a true cyan, you need a yellower red > > rather than a bluer red like PV19 to balance it, and so forth. The > > way I think of it is that in order to produce neutrals you need your > > three colors to be sort of equidistant on the color wheel, and if one > > is hue-shifted in one direction, then the others need to be shifted > > in the same direction. Which is an implication of Bruce McEvoy's > > mixing triangle: the triangle needs to enclose the center of the > > triangle in order to be able to produce a neutral black; if the > > triangle is way skewed from equilateral, it may not contain the > > center (black) and the three colors layered won't add to black. If > > that doesn't make sense, then I need to find a way to write it better. > > Katharine > > > > > > > > > > On Sep 17, 2008, at 12:08 AM, Loris Medici wrote: > > > >> "PV19 -> strong paint" is a side note, irrelevant to the main subject > >> fisheyes... I use very little of this when compared to the other > >> colors > >> I'm currently testing/trying for tricolor (BTW, it occured to me > >> that it's > >> stronger than Ivory black). So far it gives me nice reds (when > >> combined > >> with Schmincke Yellow Raw Ochre 656 - a mixture of PY42 and PY43) and > >> violets (when combined with PB29 Ultramarine Blue). But I can't get a > >> neutral black with this combination (but brown). What other pigment > >> would > >> you suggest for being able to get neutral black in tricolor printing? > >> (Tricolor -> Cyan from Red, Magenta from Green and Yellow from Blue.) > >> > >> Thanks, > >> Loris. > >> > >> > >> 16 Eylül 2008, Salı, 7:12 pm tarihinde, Katharine Thayer > yazmıÅ�: > >> > >>>> On Sep 15, 2008, at 11:33 PM, Loris Medici wrote: > >>>> > >>> > >>> > >>>> I have the same problem with the same pigment, Schmincke Ruby Red > >>>> 351 > >>>> PV19. BTW, it's a very very strong paint... Do you think that adding > >>>> alcohol to the coating mix can help? > >>>> > >>> > >>> > >>> Sorry, this doesn't make sense to me, Loris. In the pigment lexicon > >>> I understand, strength of pigment refers to its mixing power (or > >>> layering power, in our case); a strong pigment needs to be used > >>> sparingly in order to keep from overwhelming the other colors that it > >>> is mixed or layered with. In other words, with a strong pigment, > >>> you need to use much less pigment to get the same color intensity > >>> that takes more pigment to achieve with a weaker pigment. (I'm not > >>> the first person to notice this; I recently came across a paper where > >>> Demachy was making the same point.) > >>> > >>> So if the PV 19 is a strong pigment (in my mind, PV 19 is, yes, > >>> fairly strong as magentas go, but not as strong as lamp black or > >>> pthalo) then it stands to reason that you should be using less of it > >>> to balance the other colors than you might use of a different pigment > >>> (PR 209, for example, requires a much larger amount of pigment to > >>> achieve the same effect) and I would think that it would be a mix > >>> that had more pigment in it that would require smoothing out with the > >>> Everclear, not one with less pigment. Unless the purpose of the > >>> Everclear is to smooth out a watery mix rather than a more heavily- > >>> pigmented one. Or unless you're meaning something entirely different > >>> by the term. glad you're back, by the way. > >>> Katharine > >>> > >>> > >> > >> > >> > > > > > >
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