Plywood MR To ensure the quality of wood and its durability is to ensure that there is no moisture absorption or penetration. Marine plywood, PF and BWP are the best waterproof plywood in market and they have been used by industries for their durability, quality and environmental concern. Marine plywood will not be affected by water contact and cannot be penetrated with bacteria or fungi as well. BWP & PF are usually used in industries where water-contact beyond a certain period is intolerable. The two types of the marine plywood can be identified easily based on the density of their core material, i.e.. if their cores are made of layers and layers of pulp than it is a marine grade plywood but if it has short fiber core then it becomes known as bwp grade plywood