The central role of wood biology in understanding the durability of wood-coating interactions

Abstract

To design effectively for durability, one must actively and honestly assess the material properties and limitations of each of the components in the design system; wood or wood composite, and the coating. Inasmuch as wood coatings are manufactured to specified tolerances from known materials, we have control of that component of the system. Compared to manmade substrates such as steel, with wood we have virtually no control over the material properties of the substrate in coated wood systems. Despite this lack of control, with sufficient understanding of wood and the wood--coating interface, we can design coatings to meet specific criteria. Our understanding of wood and the specific nature of wood--coating interfaces is thus what limits our ability to design coatings in a highly targeted fashion. To begin to identify the aspects of wood structure relevant to coating durability, wood must be understood as a material of biological origin. Wood is a biologically renewable material, and there is no property of wood--physical, chemical, mechanical, anatomical, or otherwise--that does not derive directly from the fact that a tree made wood to suit the tree’s purposes. This paper outlines the general anatomy and chemistry of wood in a biological context, and demonstrates ways in which this information is relevant to understanding wood coatings. In particular, a discussion of wood structure in the context of microbial attack is presented to draw attention to the critical but oft-overlooked role of biological attack in experimental systems with wood or wood composite materials as a substrate. By understanding the general structure and origin of wood in a broader context, we can begin to formulate a framework to characterize wood--coating interactions and, ultimately, design specific coating systems that mitigate the weaknesses of wood as a material and capitalize on its strengths.

Citation

Wiedenhoeft, Alex C. 2007. The central role of wood biology in understanding the durability of wood-coating interactions. In: Proceedings of the Coatings Wood and Wood Composites: designing for durability, 2007 July 23-25, Seattle, WA. Blue Bell, PA: Federation of Societies for Coatings Technology, 2007: 24 p.