Polyvinyl Acetate Emulsion

PVA, Vinyl Polymer Tempera - The Colors

Pigments may be ground in advance with plain water and stored in jars, as in egg tempera technique. The pigment pastes may be taken from the jar as they are needed and tempered with the PVA medium. Such paints containing PVA cannot be kept long either in jars or tubes, but must be made up fresh as they are used, just as in encaustic or egg tempera painting. Dry pigments may be combined directly with the medium, without previous grinding with water. In this case care must be taken to mix the pigment and the medium well, so that no clumps of dry pigment particles remain unbound in the film . As in the egg tempera medium, the PVA paint should be checked to see if the proportion of pigment to binder is satisfactory. If a well-dried paint sample is rubbed with a clean cloth, it should not give up any color. Overpigmentation will cause cracking. As in any technique, pigments and aggregates must be well ground and thoroughly dispersed in the binder, or faulty films will be produced. The painter can add inert aggregates such as fine sand, marble dust, and powder clay to produce paints with heavy body or with textural granulation. The white color of the liquid PVA makes the paints look slightly whitened while they are wet, but they become darker and more intense as the PVA dries and becomes clear. [p. 203]

[Kay, Reed. The Painters Guide to Studio Methods and Materials. Englewood Cliffs, NJ: Prentice-Hall, Inc., 1983.]