Learn to paint in Acrylic paints - Step by Step
Once upon a time, when acrylics were relatively new to artists, we had problems mixing our colours. Not only was there this strange colour shift as the paint dried, but our mixes got muddy (as in Yuk!) very quickly.
Reference to this can be found in many books and videos, and is often repeated by those of us who started out in oils and never had problems before. So what gives?
Some sources suggest that limiting the number of pigments that are present in a given mixture will reduce the likelihood of a muddy end product. This is logical as far as it goes, but creates more problems. Many of our professional grade colours contain only one pigment, but some may contain three or more. Sap Green is more than just green if you check the pigment information on the label. Depending upon the manufacturer, Unbleached Titanium White may also contain earthy brown pigments. Not knowing what you are bringing to the table can sometimes result in unexpected results!
Muddy mixes are also much more likely when using mineral colours, that is, natural mineral derived pigments such as the umbers, siennas, ochre, and cadmium based pigments. In contrast, the newer synthetic pigments tend to remain clear and clean in mixtures.
We are left with several different approaches:
- use single pigment colours when possible and/or convenient. Check the label information!
- limit use of mineral pigments in mixtures.
- combination of these (I like my cadmiums! and my earth colours!).
- use another mixing method.
We don't have to get the exact colour first time around, or in a single application. Glazes and washes can be used to layer colours without actually mixing the pigments, providing an optical colour mixing and a different combined colour. This layering technique was used by the old masters to achieve the luminous qualities for which some of them were renowned.
- transparent colours are also less likely to present muddy mixtures than are opaque colours.
Use Karen's mixing charts to get familiar with your colours. By experimenting up front you are limiting problems later on and discovering just how many gorgeous colours you can mix from the tubes on hand.
This is condensed from responses by Karen Ilari and myself to a post by P Turner (21 Jan 2015).