TotalBoat varnish will seal and protect the wood from moisture while it remains intact. Once it ages and cracks, moisture can penetrate the wood and cause rot, so it is important to keep the varnish in good condition with 1-2 maintenance coats each year. It is also important to make sure the wood is completely dry before it is varnished. Sealing the wood with TotalBoat Penetrating Epoxy prior to varnishing will also help prevent moisture intrusion and rot in the long run.