Primer (paint) - Primers For Wood

Primers For Wood

Using a primer on wood before painting is mandatory for several reasons. First of all, wood is very porous and will absorb the solvent from paint, drying the paint prematurely. Because most paints undergo chemical reactions during the process of curing (for example, latex and alkyd-based paints actually polymerize when curing), they depend on water or solvent being evaporated slowly rather than being absorbed quickly by the underlying material. A layer of primer will help the paint to undergo proper, complete curing cycle.

Secondly, without a primer, several layers of paint can be necessary to completely obscure the wood grain and ensure even color.

Lastly, if wood is exposed to moisture, a thin layer of paint will still be water permeable. The end result will be warped parts, mildew, and dry rot. Primer adds to the waterproofing effect of the paint.

Quality primers are often comparable in price to finish paints, their cost influenced by the quality of binders that they use. Some specialty primers are in fact quite costly.

Primers are not necessary for a wood stain treatment that is designed to show the wood grain. On soft woods, a wood conditioner (thinned shellac or varnish) allows for more even coloring of stain. Sealers are designed to promote uniform finishes. They are designed with qualities that promote quick drying and they have high isocynate content and are not sandable. For good sanding we have primer surfacers.