What Is Wood Primer For?

Disadvantages

• Wood is a porous substance that can suffer from moisture penetration. Entering water may warp the material if it is left exposed to the elements. Many insects consider wood a necessary food source and habitat, while mold and rot thrive in it. These organic attacks can speed up its deterioration. While the patterns of wood grain may be desirable in furniture, they may be unwanted when showing through the single layers of paint on a wall. Wood in its natural, untreated form may prove less durable and desirable than other non-renewable substances such as plastic or stainless steel.

Primer

• Wood requires a primer before it receives paint. The main characteristic of primer is that it sticks to the top layer of wood and seals it. This makes it more impervious and more resistant to organic damage from mold, mildew and insects. Primer forms a nonporous layer that paint can stick to. Without primer, the solvents from paint may penetrate the wood, causing the substance to dry prematurely and improperly and peel. Primer makes only one or two coats of paint necessary to completely cover the grain and form a solid seal. Without primer, many layers of paint may be needed.

Types

• Like paints, primers may be water- or oil-based. The Home Depot recommends water-based primers for most applications because they are less toxic and dry more quickly. However, they work only under water-based paint. If the wood is stained and tends to bleed sap or tannin, it requires an oil-based primer. This type of coverage also accepts both water- and oil-based pigments. Primers are formulated for specific materials such as wood, concrete, iron and aluminum. Be sure to pick the correct one for your construction.

Use

• Before applying primer, allow the wood to fully cure and season to eliminate any internal moisture. This may require exposure lasting from several months to one or two years depending on the wood. Wood purchased from lumberyards and home centers already is properly seasoned for construction. Fill any cracks or holes with wood putty or other filler, and then sand the surface to a relatively smooth finish. Apply the primer according to the manufacturer’s instructions, which typically involves using a brush. Only one coat is necessary, so wipe off any excess primer. Wait for the surface to dry fully before painting.