Whether your kitchen cabinets are natural wood cabinets or you've painted them, a polyurethane coating gives them that extra durable finish to help them last. Polyurethane finishes protect cabinets from stains and water damage. Both finishes come in semi-gloss, satin and gloss sheens. When you decide on a product, consider which characteristics of both water-based and oil-based polyurethanes will produce the desired effect for your kitchen cabinets.
Water-based polyurethane finishes are easy to apply due to their thin consistency. You can use a bristle brush or foam brush to apply the finish. This finish dries quickly and produces slight odors in comparison to oil-based finishes. You need to lightly sand painted cabinets to prepare the wood to ensure the polyurethane adheres properly. This process dulls only the sheen of the paint and the polyurethane finish restores the shine. Sanding the surface before you apply this finish is especially important, as the water in the material can raise the grain of the wood as you apply it, leaving you with an uneven finish on the cabinets. Cleaning kitchen cabinets with a water-based polyurethane finish is a breeze with only soap and water.
Oil-based polyurethanes have a thicker consistency than water-based finishes. You need to ensure you have proper ventilation when you apply this finish, as it produces strong odors. The finish goes on fairly easily in thin coats with a bristle or foam brush, or you can thin the material with paint thinner and apply it by wiping a cloth along the grain of the wood. This type of finish works well with natural wood; over time it produces an amber tint on the wood. Clean cabinets with an oil-based finish with mineral spirits to protect the coating.
You can apply either water-based or oil-based polyurethane to unfinished or latex-painted cabinets. Oil-based products require two coats to sufficiently cover and protect the wood finish. You need to apply at least three coats of water-based products, due to the thinner consistency and tendency to show wear faster.
Regardless of the type of polyurethane you use on your kitchen cabinets, preparation is the key to a well-done finish. You need to ensure that painted cabinets are clean and dry before you add the protective finish. Sanding between coats of polyurethane ensures the material penetrates the wood and provides the best protection. If the cabinets currently have high-gloss paint on them, use low-gloss polyurethane to counteract the sheen of the paint.