This 20 min demo is part of my Choosing and Mixing Color class. An expanded version of it is part of my Painting in Acrylics class.
Acrylic glazing, done by mixing smaller amounts of paint with pouring (liquid) polymer medium, is a great way for painters to control the opacity of their paint mixes. For painters mindful of color, glazes have additional uses. Glazes can be used to add temperature, intensity and contrast to parts of our painting, without the bulk of repeated layers of pigment. They can give a watercolor feel or can be used to create very subtle gradations between values. For beginners, glazes can be a way to “test” a mix.
How Glazes Work
Glazes are semi-transparent and as such rely on light reflected by the layers of paint underneath. So, when painting a glaze over a pre-existing layer, the top layer should not be completely opaque or it will block the light reflected by the bottom layer. The bottom and transparent top layer will combine and will create a third, more luminous hue than if you had mixed them on the palette. In this example, the gray underneath combines with the transparent orange to form a subtle green.
Grisaille as Underpainting
This is a technique that dates back to the times of illuminated manuscripts. Much of the oil painting done before the 19th century was begun with a grisaille. Painters created a monochromatic underpainting in shades of gray as the way to establish volume, and laid glazes on top of it for the hues. A modern example is Tamara de Lempicka’s figurative work.
You put down one color and it calls for an answer. You have to look at it like a melody. Romare Bearden
In this example, the facial structures were laid first with a grisaille, then an orange glaze was applied and reinforced with later glazes of dark orange for the mouth, nose and ears and brown for the darker parts of the face. No glaze was used for the background or the pupils, so that the chromatic Black that I mixed could have maximum opacity.
Building Volume With Glazes
Another way to gradually saturate or desaturate color, or lighten or darken a value is to start with a base color over the whole face or object. In this case, the base color was a rather saturated orange for the skin, laid flat over the whole face. Then I used a glaze of a pastel orange and medium over this to lighten certain areas of her face. I used a dark orange to partially darken other parts. And I used a pastel orange with more white for the highlights. I did not use a glaze to paint the black hair, for maximum opacity. Unlike in the first example, here we are progressing from light to dark. A modern example is the landscape work of Peter Wileman.