Preventing Bubbles In Urethane Floor Vinish

Diluting the poly.

Preventing bubbles in urethane floor vinish.

I was applying semi gloss finish polyurethane on an oil stained birch tabletop. To prevent air bubbles from occurring at all follow these tips. Resist the temptation to shake the polyurethane prior to use. I had tried every option i could think of.

The only remedy is to sand out the bubbles and apply another coat of finish more. The most common causes for bubbles are shaking the can and improper brush prep you don t stick a brush into the finish without first soaking the bristles in mineral spirits for oil based polys or in water for water based polys. The stain may feel dry on the surface but still be wet below the surface causing the finish to bubble. This happens to floor finishers who drag the finish applicator aggressively and then must stay off the floor until the finish dries.

Stir the can prior to use and take your time. Nobody wants to do all the work of refinishing and end up with bubbles in the finish. Very smooth surface preparation. Finish brushes delicately lay on a thin clear coat to accentuate the surface below.

Stir the contents instead with a paint stick in a gentle swirling motion. I had similar problems with very fine bubbles in topcoat. Sanding between coats with very fine grit paper 220 and finer. There are several things that can cause bubbles in the finish.

Stain that has not dried before the first coat of finish can cause bubbles. Some brands of finish are known to bubble more than other brands. However if you re not careful small air bubbles can mar the beauty of the finish permanently. Heavy coats of paint levels as it dries flattens out to hide brush marks and minor defects.

When the finish hardens you have to sand them out and apply a new finish.