Prepped the aft side of the firewall for single ply BID ply. I sanded it with course sanding paper to open the grain of the wood, I then vacuumed it and took a damp cloth to wipe it down and further open the grain. After allowing to dry, I made the one ply BID layup. First I put a thick coat of pure resin and let that soak in a bit. Then added the cloth and more resin, straightened the fibers, wet it out and covered with peel ply and wet that out.
