Home Forums The Learning Center Color Theory and Mixing Combining transparent and opaque paints

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  • #993327
    Barbareola
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        When I paint with gouache, by definition the paints are opaque. The watercolour paints I use are all transparent and staining. Thus when I use these media, it is either transparency or opaqueness.

        However with the acrylic paint that I use, some colours are transparent, some are opaque. Recently I have run into problems with using them in the same painting. I’m having especially problems with painting pink and rose flowers. I tried to use a quinacridone magenta as a base colour. Toning it down for shadows while keeping the transparency was no problem. But when I tried to add zinc or titanium white for the highlights, the paint turned totally opaque which clashed ungainly with the transparent parts of the picture. That was made all the worse because not only did the paint turn transparent but it also shifted the hue dramatically towards blue.

        So I wonder – how do manage to combinde transparent and opaque paints in a single painting so that the painting still looks harmonic? How do you make pinkt lighter without making it also bluer?

        I hope you have some tipps to share. Thanks in advance. :)

        #1237131
        KolinskyRed
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            What would happen if the Quin Magenta were applied so thin so that it’s transparent over top the white of the support (No Titanium White)? Or mixed with a glazing medium? Or does it look like the same effect? Samples here:
            http://www.goldenpaints.com/products/colors/heavy-body/quinacridone-magenta

            And a comparison of reluctance curves between a Quin Mag + Gel and QM+ TtWt, Graph 7 in Sarah Sands excellent article the “Subtleties of Color”: http://www.justpaint.org/the-subtleties-of-color/

            I really enjoyed the article, very helpful. The following comment explains Graph 7 (I know the text says Graph 4, but look at Graph 7), noting what she wrote about a “scintillating pink”:

            “Another aspect to notice is the difference between the mixtures of Quinacridone Magenta with gel versus Titanium White (Graph 4). While the one with gel reaches a level of reflectance for cooler reds that is nearly equal to the same mixtures with white, there is a continued, extremely shallow level of absorbance in the 525-575nm range, which would be descriptive of a complementary shade of Green. Because this complement is suppressed, this transparent mixture is able to possess a very high and brilliant chroma, creating a scintillating pink that is impossible to achieve when adding white.”

            I enjoy reading the articles in Golden’s Just Paint archive. They’re great.

            As to transparent and opaque passages together in a painting, I’m not advanced enough to say what I would do, but as I’m climbing up the learning curve, I see a lot of advanced painters implement this. I think the rationale is a systematic approach where it becomes part of the design. Opaque has an effect on the pigments versus the transparent, both stand alone and in mixes, grading from a strong opaque mix to semi opaque to more transparent. Paints can “look” different in those states. “Classic painters” would in a most general nutshell, reserve the transparents for darks/shadows, and use the semi-opaques in the lit areas, and use opaque paint, often thickly, on the very lights, and highlights – conveying a solidity, almost 3-D effect if they wished. But I don’t think a painter has to go that far (the 3-d/structural part). Is the transition between the two effects too much? Perhaps creating more of a gradation reserving an abrupt change for visual effect?

            I remember reading that Lucien Freud remarked it took him his whole life to realize that learning to paint was learning about paint (his paintings, during his lifetime, sold for millions).

            Hope this might be of help. The attachment is from the same article, a pdf link at the bottom of the article page where the graphs can be seen in great detail (the left one is Quin Mag with Gels, the right one is with Titanium White).

            #1237130

            Nice reply from KolinskyRed there, very technical. Golden is a remarkable ressource for data that way, I agree.
            The trouble using gel instead of titanium white, to avoid the shift towards blue is, I guess, that you want opacity here, to make the highlights lighter than the underpainting.
            Opacity is not binary, pigments have varying degrees of opacity/transparency, and paints even more so, due to varying degrees of pigment and possibly filler content, as well as the binders own slight color, at least until cured. Some of your watercolors are probably less transparent than others. If pigment load is high, some might very well be semi-opaque, undiluted. And indeed your gouache is only always opaque if chalk (or the like) was used to make it, or if no transparent pigments were used. If you have done the same flowers in quinacridone magenta using gouache, your gouache definately contains chalk to make it opaque.
            Then, maybe try the same with your acrylic painting? Various molding/modelling pastes of different sorts are made with chalk. Or use Zinc White (That should contain less blue, I believe, and it is much less opaque). Or a combination :-). If what you’re dealing with, is a difference in gloss level, between the quinacridone magenta and titanium white, remember you can fix that by adding a bit of gloss gel or gloss medium on top.
            You are using artist grade paint, right?

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