Effects of thermal modification of oak wood upon selected properties of coating systems

Abstract

In the last few years there has been an increased demand to change the natural color of valuable hardwoods without chemicals for use mainly in indoor parquet floors. In this study, wood samples from oak (Quercus petraea L.), one of the most used species for parquet, were heat treated (ThermoWood method) at 190 °C for 2 h and at 212 °C for 1 and 2 h. Untreated and heat treated wood surfaces were coated following two different applications: type 1, with a single layer of sealer (50 g/m2) and type 2 with two layers (35 g/m2) using a nanolacke varnishing system. The objective of this study was to investigate surface properties including adhesion, glossiness, pendulum hardness, and color (L*, a*, b*, ΔE*, ΔL*, Δa*, and Δb*). With heat treatment the lightness decreases, and its decrease is higher for higher temperatures and treatment times. Type 2 coated wood presented a slightly lower lightness decrease. The experiment showed a slight increase followed by a decrease in redness (lower a*) and a clear decrease in the yellow tone (b*). The total color variation increased with the intensity of the treatment, while the glossiness decreased (more for Type 1 coated wood). The adhesion strength and surface hardness decreased with the heat treatment in both the Type 1 and Type 2 coated wood samples. The decrease in adhesion was higher for Type 2, reaching 67%, while the decrease in surface hardness reached about 18%.

Influence of Thermal Modification in Nitrogen Atmosphere on Physical and Technological Properties of European Wood Species with Different Structural Features

“…The a* parameter increased, b* decreased in black locust after heat treatment in nitrogen atmosphere [20] or the values of a* and b* decreased for pine wood after modification in water steam [65]. Similar results were obtained for oak wood by Gurleyen et al [66], which investigated the effect of thermal modification and application of a matt varnish coating on the colour of the wood. The obtained results indicated a decrease in the L* parameter of thermally modified oak wood (212 • C for 2 h) and varnished to 17.9 from 56.8 recorded for native oak wood after varnishing.…”

Subterranean Termite Durability of Three Inferior Wood Species Collected From Indonesian New Guinea Coated With Two Coating Systems

“…These results summarize that coating systems had an impact to enhance the life services of wood material from subterranean termite tested. Coating systems are usually employed to extent the change of color, protect wood surface from biotic and abiotic factors, and mostly for softwood end products (Gobakken and Westin 2008;Gurleyen et al 2019). It is also supported that coating systems could protect weight lost of wood during service, mainly due to termite attack (Amemiya and Marsuoka 1979).…”

Propose of models to estimate toughness as a function of physical and chemical properties of commercial thermally modified hardwoods

“…On commercial purposes, several methods are available for wood thermal treatment, like Le Bois Perdure ® , Plato Wood ® , Reti Wood ® and ThermoWood ® [6,[11][12][13][14]. The most utilized method on market, Ther-moWood ® , is divided in three phases: dry and heat the wood until 130°C, then the thermal modification, elevating the temperature from 180°C until 200°C and cool and stabilize wood, controlling humidity content [14][15][16][17].…”