**Teresa Lovaglio 1, Wolfgang Gindl-Altmutter 2, Tillmann Meints 3, Nicola Moretti <sup>1</sup> and Luigi Todaro 1,\***


Received: 26 July 2019; Accepted: 3 September 2019; Published: 5 September 2019

**Abstract:** The main purpose of this study was to investigate the hydrophobic effect and chemical changes induced by thermo-treatment and alkyl ketene dimer (AKD) on the surface properties of Alder (*Alnus cordata* (Loisel) Duby) wood before and after an artificial weathering test. Thermal treatment was conducted at a temperature of 200 ◦C for 4 h in a thermo-vacuum cylinder. Then, the paper sizing agent, AKD at different concentrations of a solution of 0.1%, 0.5% and 10% was used as a potential hydrophobizing reagent for untreated and thermally treated alder wood surfaces. The contact angle measurement, ATR-FTIR analysis and colour variation were carried out for the samples. The preliminary results revealed that the contact angle values of the wood materials increased with thermal modification. However, the influence of the thermal treatment on hydrophobicity was small when compared to the substantial effect of the AKD application in this respect, and also after the artificial weathering test. The FTIR analysis supported the hypothesis that AKD could make bonds chemically stable even when using a small concentration of AKD. The findings acquired in this work provide important information for future research and the utilization of the AKD on lesser-used wood species.

**Keywords:** underused wood species; thermo-vacuum treatment; surface degradation; hydrophobic effect
