Toward energy efficiency through an optimized use of wood: The development of natural hydrophobic coatings that retain moisture-buffering ability

Abstract

The hygroscopicity of a wooden material or the ability to absorb, store and release moisture helps to naturally regulate the indoor climate by dampening humidity variations and avoiding extremes. This phenomenon, known as moisture buffering, is an energy-efficient way of moderating moisture levels in a living space, improving air quality, and influencing the health and comfort of the occupants. This work focused on developing a surface treatment that preserves the natural ability of timber to buffer moisture vapor while increasing the resistance to liquid water. For this purpose we suggest a method based on a natural non-continuous coating of hydrophobic Carnauba wax particles. The coating was compared, in terms of water repellency and moisture buffering efficiency, to a continuous wax film and conventional coating methods like lacquer and linseed oil. The resistance of the surfaces to liquid water was studied by contact angle measurement. Moisture buffering experiments were conducted by exposing the surfaces to cyclic changes in relative humidity. It was found that coating with wax particles resulted in more hydrophobic surfaces with enhanced moisture buffering ability, while the rest of the coatings examined either reduced moisture buffering drastically (wax film, lacquer) or were not sufficiently hydrophobic (linseed oil).