A varnish topcoat can protect your painted kitchen cabinets from premature wear; however, you don't need the clear sealer if you've chosen the appropriate paint. Unfortunately, many amateurs choose less durable paints for their cabinets. Learn which paints require a protective varnish sealer and which do not, or you could end up with fading and/or chipping.
If you paint your kitchen cabinets with the correct type of paint, you don't need to apply any sort of varnish sealer. High-sheen paints, such as gloss latex and acrylic enamel, provide good protection against stains and wear. Moreover, the chemicals that provide the paint with sheen may prevent the varnish from adequately adhering.
Low-sheen paints, such as eggshell, flat and satin latex, aren't well-suited for kitchen cabinets because they aren't stain-resistant, are difficult to clean and more prone to premature wear. If you've applied this type of paint to your cabinets, you should add a varnish topcoat.
Not all types of varnish will bond to every kind of paint. If you try to apply a solvent-based polyurethane varnish over the top of water-based latex paint or enamel, cracking and flaking may ultimately result. To ensure good adhesion that will contribute to a durable finish, apply a water-based polyurethane.
Even eggshell and satin latex paints possess a small amount of sheen that could inhibit adhesion. Before you apply varnish over the top of these paints, lightly sand the cabinets with a fine, 200-grit sandpaper.
Varnish tends to sag down vertical surfaces. Over-application is the primary cause for this. When applying varnish to your kitchen cabinets, add a pair of thin coats rather than a single, saturating, heavy coat. Use a soft-bristled polyester paintbrush that will promote a slick, flawless finish; do not use a nylon brush, or the varnish may dry with ugly marks.