Warning: Tech Alert… The information below may seem somewhat technical, but it is important to the painter who wants to create a painting that will stand the test of time and to the collector who wants to understand how paintings are created and how they will last.

Acrylic paints are made up of tiny particles of plastic called acrylic polymer suspended in water colored with pigment.  When paint is applied to a support, the water begins to evaporate and the plastic particles move closer together and form a glue-like bond between the pigment and the support.  The bond is the strongest on absorbent surfaces like paper, cloth, and wood.  Plexiglas, metal, and other smooth surfaces must be roughed with sandpaper to allow the paint to stick.  The strength of the bond is important to ensure that the next layers of paint and varnish don’t peel or crack.

The strength of the paint film is also affected by the amount of water in the paint.  If the paint is diluted with too much water, the acrylic particles will be too far apart to bond properly.   Therefore it is necessary to use a low viscosity medium to thin paint for transparency rather than adding more water.  The exception is applying acrylic to paper.  Because the surface is absorbent, the paint sinks into the paper to form the bond.  So acrylics can be thinned with a lot of water for watercolor effects on paper.

Next time…. If you know how to make the paint stick, you also know how to keep it from sticking.   How does that knowledge help you?