Sometimes. Chalk-style, mineral and milk paints are designed to go onto bare wood without a separate primer. Standard latex or acrylic paint usually needs one on bare wood, because the wood soaks up the paint unevenly and can bleed through over time. The rest depends on the wood, its condition and the colour you are painting.
When you can skip primer
- Chalk-style paint on clean, sound wood. Chalk-style paint is made to adhere to bare wood with little preparation.
- Mineral and milk paints on bare wood, when the product label says it suits bare wood. See can milk paint be used on wood.
- Sound, previously painted wood in good condition, scuff-sanded and clean. A new coat of latex or acrylic can go over a sound old coat.
- Casual or decorative pieces where a rustic, textured or vintage look is what you want.
Self-priming paints are designed for clean, sound, previously painted surfaces. They are less reliable on bare, tannin-rich wood.
When you need primer
Use a primer when any of these apply:
- The wood has knots, especially in pine.
- The wood is tannin-rich: oak, mahogany, cherry, redwood or cedar.
- The finish is glossy, so the paint needs a bonding layer.
- The piece is laminate or MDF edges, which are non-porous or absorb unevenly. How to paint MDF cabinet doors covers sealing MDF.
- You are going from a dark colour to a light one, such as dark wood to white.
- You are switching from an oil-based paint to a water-based one.
Tannin bleed shows as yellow, pink or brown stains, often through white or light colours. It can appear days or months after you paint, so it is not always visible straight away.
What goes wrong without primer
- Uneven absorption. Bare wood acts like a sponge. Standard paint sinks in unevenly, so the finish looks blotchy and needs extra coats.
- Bleed-through. Knots and tannins migrate into the paint, causing stains.
- Poor adhesion. Without a sealing layer to grip the wood fibres, a topcoat can chip, crack or peel sooner.
Adding more topcoats will not stop knot or tannin bleed. It only hides the problem for a while.
Raised grain on bare wood
Water-based paint raises the grain of bare wood, leaving it rough. Dampen the wood lightly, let it dry, and sand with 220 grit before you paint. You can also sand lightly after the first coat, once it has dried, and before the second.
Pick the right primer
For tannin-rich wood, knots or a white topcoat over dark wood, use a shellac-based primer such as Zinsser B-I-N. Oil-based stain-blocking primers also work. Water-based bonding primers grip slick surfaces well but block tannins poorly, so do not rely on them for bleed-prone wood. For a full comparison, see the guide to the best primer for wood furniture.
The same reasoning applies to pine. See can you paint straight over pine for the knot-sealing steps. For the wider choice of paint types, see which paint to use on wood furniture.
Safety
- Shellac primers are alcohol-based and flammable. Ventilate and keep flames away.
- Wear a respirator with organic-vapour cartridges for solvent primers.
- Test old finishes for lead before you sand.