I'm repairing my boat where I bumped up against the dock. It made a mess there the dock dug in. I ground the fiberglass down to where it was not damaged any more. I filled with fiberglass resin and mesh. It's all sanded smooth and I'm putting the gel coat over the repair to seal it. I'm brushing the gel coat on with a small brush. I'm getting tiny Bubbles in gel coat repair. They are very similar to the bubbles you get with drywall when it's spread. My surface is clean and dry and wiped down with acetone. What is causing this, and how do I get rid of them?