How To: Paint MDF
Want to makeover your MDF cabinets or shelves? Follow these steps to give this increasingly popular material a clean, smooth coat.
Medium-Density Fiberboard, known simply as MDF, is common for both furniture and home construction these days. The inexpensive engineered wood material—a composite of sawdust and resins, fused together in a high-heat, high-pressure process—comes in 4’ × 8’ sheets and smaller project-sized boards ranging from 1/4” to 1” thick, much like boards of plywood.
But unlike plywood, which is manufactured from many thin sheets of wood veneer, MDF is free of the knots, rings, and grain of real wood. The result? A composition that is very easy to cut, and therefore often used for such upscale applications as custom trim work and cabinetry. Plus, its hard, smooth surface takes veneer and paint very well.
Painting MDF requires an understanding of the material, however: It comes from the factory sanded to a 150-grit smoothness, so the face is ready to paint, but the edges are more porous—almost fuzzy—and require some prep for a smooth, uniform finish. Additionally, the material’s porosity also makes it unsuited to water-based products for the initial coat. Follow the guidelines here for how to paint MDF and your colorful project will turn out great!
If working on a piece of furniture, remove any hardware and set aside until paint has thoroughly dried. Then protect the work area with drop cloths to make cleanup easier. MDF produces a lot of dust when sanded, and the fine particles can irritate eyes and lungs, so be sure to wear protective eyewear and a tight-fitting dust mask.
Whether your MDF project has a factory edge or has been custom routed, the edges must be sealed to accept paint in a way that matches the smoother face of the material. Seal the edges by running a generous coat of drywall compound over them with your finger. Once it has completely dried, sand edges smooth with 220-grit sandpaper. Fill any scratches on the face of the MDF with drywall compound as well, as any mars or scratches will be painfully obvious once painted. Sand the entire piece with 220-grit sandpaper, then wipe it all down with tack cloth to remove fine dust and any remaining dirt or debris.
Prime the MDF with a solvent-based primer, such as Zinsser (buy online) or KILZ (buy online). Avoid water-based primer, as it may cause the wood fibers to swell, resulting in a surface that appears to have a raised grain (no matter how much effort you put into sanding). Use a brush, roller, or spray gun to apply the primer—whichever is appropriate for the project.
After it is sealed, painting MDF with water-based paint will produce the same results as painting it with an oil- or lacquer-based product. In other words, you can use your preferred paint on primed MDF, and you can apply the paint finish with your preferred applicator, be it a brush, roller, or spray gun—whichever best suits the project. Once the first coat of paint feels dry to the touch, assess if your work needs a second coat. If you spot any patchiness, cover the entire MDF project with another layer of paint.
Allow paint to dry thoroughly. Then, apply preferred sealer (polyurethane, lacquer, wax, etc.) if you expect your MDF project to get daily use in order to preserve your paint job. For example, painted cabinet doors could benefit from an extra layer of protection from wear and tear; MDF crown molding, on the other hand, will be out of reach and therefore not necessitate a sealer.
When project is completely dry, replace any hardware you may have removed and step back to admire your work. After a coat of color, MDF will look just like any other painted wood. In fact, DIYers can create custom trim, wainscoting, or furniture partly with MDF and partly with wood, and once painted, the final piece will blend seamlessly together.