Eastman Chemical's Perennial Wood is modified throughout on the molecular level to resist the  moisture with a proprietary TruLastTechnology incorporating an acetylating process. This uses heat, pressure and an organic compound to permanently expand the wood's cell walls to a fixed position—helping the wood minimize water absorption.

The resulting Perennial Wood boards and components are said to remain straighter, smoother and harder, and are three times more resistant to shrinking and swelling—without compromising the wood's natural appearance.