Varnish finishes protect wood floors from moisture and scratches. But they also make floors resistant to painted finishes. If you roll a coat of paint directly over a varnished floor, the paint will start peeling soon after application. A base coat of primer can help promote adhesion. You need to use shellac primer or the primer will not adhere well to varnish topcoats. If you want to transform the look of your varnished floor with a painted finish that will last, prepare the floor correctly and use the correct tools.
Clean the varnished floor using a mop. Let the floor dry for about three hours.
Sand the varnished floor using a floor sander. Move the floor sander in the direction of the wood grain to prevent splintering. Continue until the floor appears slightly dull.
Remove visible sawdust using a shop vacuum. Remove unseen dust particles by wiping the varnished floor with tack cloths.
Coat the varnished floor with a shellac primer using a roller. Attach your roller frame to a roller extension pole to ease the application process. Start at the end of the floor farthest from the doorway. Move the roller across the varnished floor in a vertical motion. Work toward the doorway. Let the shellac base dry for three hours.
Wash your tools with denatured alcohol.
Paint the varnished floor as you primed it. Use an acrylic paint specifically made for flooring. Let this finish dry for three hours before stepping onto the floor.
You also can finish the floor using an epoxy floor paint.
Latex primer won't stick to a varnished floor. Use a shellac primer, or the finish will come loose.