Acrylics, Pigments, Color and Plastic Goo

I had an interesting conversation yesterday with an online friend/fellow artist, in which my friend asked me about color theory and pigment in acrylic painting. The conversation was interesting enough, in fact, to inspire a blog post here!

All artists deal with color theory. Perhaps I should say that all artists deal with the elements of color, which are hue, shade and highlight. Even artists who work exclusively in graphite or in pen and ink create highlights and shades by use of more or less of the medium. But as soon as you add color, you get a much more complex palette of shade and light. You have the element of the color of the subject, which we call local color; you also have the colors that define shadows; and finally you have subtle hues and shades of color that help the eye discern form and texture. For acrylic painters. all of these elements must be expressed by using the palette of paint colors and textures available to us.

Diana

A painting of the Goddess Diana, above, shows how extremes of dark shadows can be expressed in what might be considered bright colors. This painting used a lot of synthetic pigments (see below).

To first discuss pigments in acrylic paints, let’s look at what we mean by acrylics.To quote this site,

Acrylic paint consists of pigment suspended in a binder of acrylic polymer emulsion. Water is the vehicle for the acrylic polymer emulsion.

In simpler terms, acrylic paints, whether purchased in tubes, in jars, or mixed by the artist, are bits of color (pigments) in a viscous goo of liquid plastic. They are water soluble when wet, and various amounts of water can change the viscosity of the paint; once dry, they are impervious to water. In fact they are tenacious; if acrylic paint dries on your clothing, it will never come off (as every art student finds out, for better or worse). This is why acrylic paints are used on every surface (ground), from house walls and exteriors to fabrics to wood to canvas to paper to rocks.

dancer sketch

Dancer: in this painting acrylic paints were used with a lot of water, giving them a ‘watercolor’ look, on paper. The greens used are synthetics (see below).

Since the polymer, the clear plastic goo which houses the color, is identical in every jar or tube of acrylic paint, the element we need to focus on when painting with this medium is the color, which is infused into the polymer by pigments, or bits of a colored substance.

To quote this site:

Pigments traditionally started out as earth or rocks. Some of the oldest pigments are made from coloured earth, like yellow ochre and are called earth colours, they tend to be muted in colour. Different oil colours have been created as new pigments and manufacturing methods have been developed. These modern pigments are brighter and man-made.

(If you are scientifically minded, take a look at this discussion of the chemical processes of polymers, binders and pigments).

Basically there are three types of pigments, and each respond to a surface (ground) differently:

  • Inorganic earth pigments, such as yellow ocher or raw sienna; these come from mineral sources.
  • Organic, usually from plants; cadmium acrylics are among these.
  • Syntheticl pigments; usually with long chemical sounding names, like dioxazine or phthalocyanine.

(This manufacturer’s website includes a full rundown of the make-up of each paint’s pigment, and can give you a really good idea of the materials used in each type of pigment).

Paints either coat a surface or stain/dye a surface: the more natural pigments coat a surface, while the artificial pigments stain or dye the surface. Here’s an overview of each type of pigment:

The most “pure” paint is the inorganic pigment paint. These were the first paints ever used by humans, and include various ochers, siennas and umbers. These are all made from natural earth sources, rocks and dirt; they are the types of paint that prehistoric people used to paint cave walls. You also have things like cobalt blue and ultramarine (made from salt and aluminum). When applied to a ground, such as canvas, these paints will give matte colors but they will spread evenly and catch light beautifully.

aimee 2

Aimee; almost exclusively using inorganic paints, especially yellow and red ocher.

Organic colors are just a tiny bit trickier, as they are brighter, so harder to match with each other. It is important to remember that a color is only light or dark compared to the colors around it; so when using organics, like cadmium red or orange,  you may need to surround them with inorganic colors to emphasize their brightness. Otherwise you get a palette that is glaringly bright, which can look amateurish or “crafty.” Of course some artists can pull off a really bright palette; I guess it depends greatly on your technique and subject matter. (I should mention here that I always have a color wheel nearby when I paint!).

Finally there are the synthetics, which I think are the hardest to use. They are dyes, and when used without an inorganic underpainting they will be somewhat transparent, like watercolors. If you want a transparent palette they are perfect to use. But if you have areas of transparency and areas of opaque on the same ground, your work may look inconsistent and perhaps odd, as areas are catching light very differently. Again, a clever artist might be able to pull that off.

I use synthetics very sparingly in my painting, and I will often use synthetics over an undercoat of inorganics: I might for instance use phthalo blue over a base of colbalt, or over a cadmium hue. Remember that the undercoat will show through the synthetic, so you will get a slight blend of the tones. So if I want a slight purple, let’s say to harmonize a bright green subject, I might paint a base coat of Prussian blue and place a quinacridone violet above it to get a purple sheen (though the violet will be the perceived, or local, color).

At some points in my painting career, I only used inorganics, especially ochres and siennas, with a very small amount of organics in my subject. The Bear Wife is a good example. Everything in the painting is an inorganic, except the blanket and the bear’s eyes, which are cadmium red (even the blue is inorganic, as it is ultramarine, made of aluminum and salt).

The Bear Wife

sketch 4

Above, this sketch book study used only inorganics, especially yellow ocher, raw and burnt sienna, and raw and burnt umber.

Uksakka (below) is much brighter due to the use of both organic and synthetic greens: in the background, I used layers of organic and synthetic colors to get a bleed of reds, yellows and greens that show brown or burgundy when seen in various light sources (to simulate the different stages of blood drying, as Uksakka is a figure in Sami mythology associated with menstruation and birth).

Uksakka

Arianhrod is also all inorganic (Cadmium reds and yellows) , but they appear bright due to the black background.

Arianhrod

Juksakka

Juksakka uses some synthetic paints, especially in the background. This gives the canvas a slightly airy, sky-like feel.

The best way to get a feel for the coverage of each type of pigment is simply to use them! Make a color wheel of each type of paint, first separately (all inorganics, all organics, all synthetics), then using all three types. Mix colors from each with its own type, then combine colors across types. Experiment with how synthetics sit on top of inorganics or organics. Experimentation is better than fifty written sources on the subject!

I hope this discussion of pigments is helpful to some artists. Blame my art school professors: they were very concerned with color and viscosity. All artwork in this post are mine: please do not use without permission. Thanks.

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