Eliminate Air Bubbles in Minwax Polyurethane

Minwax polyurethane is a protective varnish that is used to seal wood stain. It is an oil-based, clear finish that is applied in several coats after staining. It is fast drying and appropriate for any indoor wood surfaces, such as cabinets, bookcases, trim and doors.

To prevent air bubbles from occurring, which can affect the quality of the finish, these steps should be followed.

Step 1: Stir the Can Prior to Use

Resist the temptation to shake the polyurethane prior to use. Stir the contents with a paint stick in a gently, swirling motion. This will reduce the chance for bubbles to form and be applied to the wood surface you are working with.

The creation of bubbles is more a function of the motion and speed of the brush than any other factor. What this means is that if you take your time when applying the polyurethane finish to the wood, there will be less of an opportunity for air bubbles to form.

Step 2: Use a Natural Bristle Brush

There are many different types of brushes that can be used to apply finish to wood. However, to reduce the chance for bubbles to form, you should use a natural bristle brush. A natural bristle brush will not create foam or bubbles when used to apply the finish.

Step 3: Avoid Creating Foam

Apply the Minwax polyurethane finish with even strokes to avoid creating foam. Foam will cause bubbles to form and create a messy, uneven finish.

Step 4: Tip-Off Finish

Use a “tip-off” motion when stopping the application of finish on the wood. Tipping off occurs by simply running the brush stroke across the wood and lifting the brush upward at the end of the stroke. Run the brush lightly over the area to pull the finish over the surface. This creates an even application of the finish and prevents bubbles from forming.

Be aware that following these steps recommended by the manufacturer may still not eliminate all of the bubbles. In those instances where bubbles still occur, allow them to dissipate on their own. Any remaining bubble can be removed with mineral spirits for a period up to 20 to 30 minutes after drying. Gently wipe the bubbles away and, if necessary, reapply the polyurethane finish to the area.

Following these steps should help minimize the creation of air bubbles and make your wood finishing projects more successful.