How to spray paint wood. Choosing the materials

How to spray paint wood. Choosing the materials

Spraying wood with an aerosol paint has its own specifics, and ignoring them puts a good result out of reach. Let us take it in order.

Surface preparation – priming

There are several reasons why wood has to be primed before a paint or a varnish goes onto it.

First: to deal with the raised grain that makes the surface so rough it becomes unpleasant to touch. When the first coat of a coating material goes onto bare wood, the wood fibers stand up and leave the surface unpleasantly rough. Further coats will not remove the raised grain. That is why the surface has to be sanded with fine sandpaper once the first coat has dried, and only then the following coats can go on. Good choices against raised grain are the universal acrylic primer KUDO® KU‑210X and the nitrocellulose matt varnish (it works very well as a primer) KUDO® KU‑9009. The alkyd primer KUDO® KU‑200X is the least convenient against raised grain: it dries slowly and sands poorly once dry.

Second: to hide the grain of the wood and some minor defects and to get a level, smooth surface. The best option here is the universal acrylic primer KUDO® KU‑210X. It fills the pores well, hides small irregularities, can be applied in a fairly thick coat and can be sanded. Paint applied over this primer lays down evenly and does not sink into the wood, so the surface comes out level and smooth. And if the grain of the wood has to be preserved, it is better to prime with the nitrocellulose matt varnish KUDO® KU‑9009. Third: extra protection of the wood against the weather. The alkyd primer KUDO® KU‑200X is good here, but it makes sense only once the grain has been raised by a first coat of another primer and sanded down.

Applying the paint

Wooden surfaces can be painted with acrylic, alkyd and cellulose ester (automotive metallic basecoat) paints.

Acrylic aerosol paints fall into solid colors (non-metallics) and metallics. The non-metallics of the KUDO® range are the satin SATIN RAL and the universal fast-drying RAL paints, high gloss and matt. SATIN RAL and the matt paint can be applied without priming. The painted surface then keeps its texture and looks original and attractive in its own way. SATIN RAL is also very pleasant to the touch and gives a silky feel. A gloss paint should not be applied without priming: in places the coating sinks into the pores and looks like a defect. If the texture is not wanted, acrylic paints have to go onto a primed surface, and the best primer for that is the acrylic KU‑210X.

Acrylic metallics SILVER GRAIN FINISH, REFLECTIVE FINISH and MIRROR FINISH differ in the type of pigment (more about pigment types here), but all of them go onto a previously primed surface only. The primer is the acrylic KU‑210X.

Cellulose ester automotive metallic paint also goes onto an acrylic primer.

Alkyd aerosol paints directly on wood make little sense — sanding the raised grain becomes a problem, so the wooden surface has to be primed first. Alkyd paints behave in their own way during application, drying and polymerization, so we recommend reading about them here first. The primer can be either acrylic or alkyd.

Topcoat – applying the varnish

A varnish can go both over the paint and directly onto the wood.

The paint has to be varnished only if it is a cellulose ester automotive metallic: there a varnish is mandatory. The best choice is the 1K acrylic automotive KU‑9010, and the universal acrylic KU‑9002 and KU‑9004 (gloss and matt) can be used as well. Varnishing wood, on the other hand, can serve several purposes. In any case, do not forget that the first coat of varnish has to be sanded down to remove the raised grain.

Improving the look of a wooden surface. Acrylic varnishes KU‑9002 and KU‑9004 (gloss and matt) and nitrocellulose varnishes KU‑9008 and KU‑9009 (gloss and matt) are used for this. Acrylic varnishes give a level, smooth surface and moderate protection against the weather. Nitrocellulose varnishes emphasize the grain and are meant for interior use only.

Protecting wood against moisture and other weather exposure. The best option is the alkyd spar varnish, KU‑9003 gloss and KU‑9005 satin. It has an alkyd urethane base and therefore dries fairly slowly, so the first coat can be the nitrocellulose matt KU‑9009, which dries very fast: it deals with the raised grain, and the spar varnish coats go on after it. The result is a gloss or matt, perfectly smooth surface with no texture. One more way to protect wood against the weather is Wood Stain & Varnish KU‑904X, which at the same time protects the timber from biological damage: blue stain, mold, rot, fungus and wood-boring insects.

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