I have two pencil eraser size chips on back of boat (bottom). I have a white gel coat and have been thinking of using the evercoat scratch repair gel coat system. Now, I have read the reviews and most say it did not harden. Is this because they did not block the air from the repair? Has anyone here used it with success? If so any tips? I know color matching is a challenge but you will not ever see it unless you crawl under.