You can use chalk paint straight over varnish as the paint stick to the surface well and doesn’t require sanding or priming in most cases. But it’s a must to apply a sealing coat for protecting the paint. It’s because, although the paint will stick to the surface, there might be some problems like bleeding or cracking of the paint.
So, yes, there’s a chance that you might face some problems. If you’re working on dark wood with light-colored chalk paint, chances are the dark wood will bleed through. Over time, you may notice a crackle effect as well.
And, here’s the good news- you can get rid of the problems by simply sealing the paint with a coat of shellac before you start the project.
Can You Use Chalk Paint Straight Over Varnish?
One of the many benefits of chalk paint is that it adheres to most surfaces without the need for sanding or priming as long as the surface is dry and clean. The same applies when using chalk paint over varnished wood. However, if you ask, I would go for a light sanding first, targeting the rough spots that might exist.
This is because paint sticks better to a smooth, sanded surface. Even if there is only a minimal chance that the paint will begin to peel in a year or so, why should I take the risk?
According to some experts, you can possibly avoid sanding or priming a varnished wood before applying chalk paint if you will wax or seal the paint (with lacquer) after it dries.
In addition, there are two occasions when you shouldn’t use chalk paint straight over varnish. The first one is when the varnished furniture is old, and the second one is when you use light-colored chalk paint over dark finished wood. In both cases, there is a possibility that the wood will bleed through.
In these cases, and according to what Annie Sloan suggests, you should first paint your piece with a shellac-based stain-blocking primer. If you’ve already used chalk paint on varnished wood and are experiencing stain bleeding, you can apply a coat of stain blocker directly over the paint. Remember to use a cloth pad to spread the stain blocker evenly across the affected area. The stain should be blocked with one or two more coats of stain blocker. Wait until it is completely dry before beginning to chalk paint again.