You do not need to apply a polyurethane finish to painted kitchen cabinets if you've used a durable paint. If you chose a less durable paint, a clear polyurethane topcoat can help prolong its life by protecting it from premature wear. Unfortunately, not all polyurethane finishes are suited for all types of paint. Learn which paints require a polyurethane finish and which do not. Choose the correct type of poly, or finish failure could result.
High-sheen paints, such as gloss latex and acrylic enamel, are stain-resistant and durable enough to withstand duress. If you've painted your cabinets with one of these types of coatings, you do not need to add a polyurethane finish. If you painted your cabinets with a low-sheen flat, eggshell or satin latex paint, you can add a polyurethane topcoat to protect the finish from stains and fading.
Solvent-based polyurethane is suited for cabinets coated with oil-based paint. It is not suited for cabinets coated with water-based flat, eggshell or satin latex paint. if you apply a solvent-based polyurethane over a water-based finish, potential adhesion problems could lead to flaking. Because solvent-based polyurethane is less flexible than water-based undercoats, cracking can sometimes occur. For best results, use solvent-based polyurethane with oil-based finishes.
Water-based polyurethane is well-suited for low-sheen flat, eggshell or satin latex paint. If you painted your cabinets with any of these paints, apply a water-based poly over the top to prolong the life of the finish. Do not apply water-based polyurethane over the top of gloss latex and acrylic enamel. Not only is this unnecessary, but the high sheen is likely to prevent the poly from properly adhering.
Choose the proper paintbrush when applying polyurethane. Use a natural-bristle paintbrush when working with solvent-based poly; use a synthetic brush to apply water-based polyurethane. Though you can use a synthetic nylon-bristle paintbrush to apply a water-based poly, a polyester-bristle brush will provide slicker, more attractive results.