Will Acrylic Latex Paint Adhere to Varnish?

Compatibility

• Latex paint is a bit of a misnomer these days as it no longer contains latex, which used to act as the binder in water-based paints. Acrylic resin is the binder of choice now, appreciated for its hardness and durability. Varnish is an old-fashioned, oil-based sealer that is thinned with mineral spirits rather than water. The standard wisdom regarding compatibility is that you can usually put an oil finish over oil or latex, but never latex over oil.

Preparation

• One issue with varnish is its gloss. Varnished surfaces need to be de-glossed by sanding with 120-grit sandpaper, which roughens up the surface enough that primer will stick to it. You'll also need to prime the sanded varnish. Primers provide a suitable intermediate layer between incompatible materials such as varnish and acrylic latex paint.

Choosing a Primer

• You cannot put latex primer on top of any oil-based finish, including varnish. You'll need to use a solvent-based primer, such as oil primer or white-tinted shellac, which is alcohol-based. Oil primer is the old-fashioned favorite and does a good job. Shellac primers have the advantage of being quick-drying. They also have excellent stain-blocking qualities.

Tips

• Sanding between coats of primer and top coat ensures a smooth finish and excellent adhesion. Don't sand after the last top coat. You can use either a brush or a roller, depending on the texture you want to achieve. As an alternative to acrylic latex paint, you can use an oil-based top coat and forgo priming although you'll still need to de-gloss.