Air bubbles sometime happen. They are an absence of resin. The next time you laminate over fin boxes wait a few minutes and if you see any air bubbles use the extra resin left in your mixing bucket (or off the floor if you have none left) and dap more resin into the air bubble. It will force the air out and have a clean lamination over the fin box.To fix these voids simply mix a small batch of resin and drip it into the holes. Fill them up then sand them down flush with the board again.