hello , the tail of my surfboard got broken and I am planning to fix it as boards over here costs a fortune , so basically what I did is that I bought polyurethanfoam of the same density and poured it into the broken part to fill it up , I couldnt get it perfect , would that ruin my board ! and can I apply the new layers of fiberglass over the old fiberglass or do I have to remove it completely ? .
My second question is that am building a skim board out of blue xps and I got lots of epoxy residue after gluing the stringer on top and bottom of the board and it is preventing me from making the rocker , I am using hand file sanding paper ,I cant seem to get over that epoxy , can you please tell me what should i do ?