Air bubbles typically occur in a polyurethane hard coat due to moisture. Urethane is a moisture-sensitive material, so if it reacts with a substantial amount of moisture in the environment, it will cause a foaming reaction that generates these air bubbles.

Make sure you’re working in a temperature-controlled, non-humid environment. We recommend applying the material around 72°F. Avoid using hard coatings over a wet or damp substrate. If you apply them over wood, it should contain less than 11% moisture.

Check out VFI’s tech piece to troubleshoot bubbling issues.