How to Apply Polyurethane Finish
How do I apply polyurethane without getting bubbles? Is it better to apply with a sponge brush or a bristle brush? -Michael
I prefer a high quality bristle brush, though a sponge brush works pretty well and has the advantage of being disposable. Make sure the temperature of the project you are finishing, along with the can of finish itself, are within the range specified on the can, and that both have had adequate time to adjust to it.
Don’t shake the can. Instead, stir the finish slowly until it is mixed well. Whenever possible, apply the finish to horizontal rather than vertical surfaces to prevent runs.
Apply the polyurethane evenly and smoothly, overlapping your brush strokes to keep a wet edge, and don’t go back over the finished work once it has begun to dry. If you notice a bubble while the finish is still wet, try popping it with a pin.
Good luck with your project,