How to Apply Polyurethane to Cabinets without Bubbles

Mix the polyurethane carefully with a wooden paint stirrer. Stir very slowly so the liquid is well mixed. This will prevent air from getting whipped into the polyurethane, which will cause tiny bubbles that may get trapped in the finish.

Pour the polyurethane directly onto one of the horizontal surfaces of the cabinets. Keep the can close to the surface and pour slowly. Spread the polyurethane with a foam or lamb's wool applicator. This type of tool won't leave brush marks and makes it easier to prevent bubbles from forming since there are no bristles where air can get trapped and transferred to the finish.

Work slowly, making full, even, straight strokes with the applicator. The faster you move the applicator, the more likely you are to create bubbles with the friction. Don't stop moving abruptly and try to drag the tool from one edge to the other whenever possible. This method will promote a smooth, even coat.

Allow the first coat of polyurethane to dry. As it dries, it tightens up while bonding to the wood, which may make the wood grain rise slightly -- this is normal. Sand the polyurethane very lightly -- just enough to scuff it up a bit -- with 400-grit sandpaper.

Wipe the cabinets down with a damp cloth, which will remove any dust you created by sanding the polyurethane. Apply between two and four more coats of polyurethane in the same fashion.