Painting Over Varnish With Latex

Properties

• Two primary types of finishes are used to protect wood, including penetrating finishes and film-forming finishes. Varnishes, latex paints, oil-based paints and solid color stains fall into the film-forming category. Varnishes dry clear, allowing the natural wood grain to be visible. While varnishes are hard, they are also subject to degradation by exposure to the elements, particularly full sun. According to the U.S. Department of Agriculture, the life span of varnish is only two to three years before it begins to crack and peel.

Latex Paint

• Latex paint is another type of film-forming finish. Latex, or water-based, paints have color pigments that completely shield the coated wood from exposure to ultraviolet solar rays. Latex paints also allow the wood beneath the coating to breathe and expel water, which may contribute to a longer life span of seven to 10 years. If you wish to take advantage of latex paint's longer life span by painting over a surface that has already been coated with varnish, you will need to first prepare the surface.

Surface Preparation

• Latex paint will not adhere to a varnished surface. Neither will oil-based paint. You must first prepare the surface before applying a coat of paint; otherwise the paint will peel off in sheets once it has dried. Start by removing the old varnish by sanding down the surface. Be sure to get all the nooks and crannies. Any area that still has varnish on it will allow the paint to be easily shed. Remove all dust from the surface by cleaning it with a household cleaner such as ammonia. Rinse the surface with water and a soft cloth to remove any remaining cleanser and dust. Allow the surface to dry completely before applying a coat of latex paint.

Painting

• Once you have properly prepared the surface, you should apply a coat of primer that is specifically designed for that purpose. Allow the primer coat to completely dry. Apply the latex paint to the surface using any method that is appropriate to the surface. If you are painting a large, flat area, such as a wall, you may wish to use a paint roller. If you are painting a decorative piece, such as a picture frame, you may wish to use a brush. Allow the latex paint to completely dry before touching it.