Poly-Clad® specially-engineered marine plywood combines poly's resistance to feed acids with plywoods rigidity. Won't sag (unlike solid-poly), nor rot/warp (unlike wood board).
Poly-Clad® marine plywood has been successfully used by major manure-spreader & chopper-box manufacturers for years. It won't rot, rust, warp, or need refinishing. It's totally resistant to most chemicals.
Poly-Clad® 3/4" plywood is specially engineered to meet the strict performance criteria of the marine industry (US Product Standard PS I-83). It is carefully manufactured from 100%, 7-ply Douglas Fir (dried to 8% or less) and marine glue, for maximum strength and flatness.
A .030" white, high-density, UV-stabilized, poly facing and a .015" poly backing are then pressure bonded, using an exterior glue, to provide a 100% moisture barrier. Poly-Clad® facing/backing won't ever need painting. Poly-Clad® acts as a protective wear surface against abrasion and reduces shear forces transmitted into the plywood... resulting in a stronger, quieter-running elevator.