Performance of selected types of coated and uncoated modified wood in artificial and natural weathering
G Grüll, L Podgorski, M Truskaller, I Spitaler, V Georges, S Bollmus, A Steitz
The objective of the present work was to investigate the influence of commercial wood modification methods on weathering behaviour and coating performance. It was aimed to compare modification methods and to set up maps of weathering behaviour for these methods with and without a semi-transparent wood stain. Artificial and natural weathering trials were carried out with a selection of different types of modified wood. Unmodified pine sapwood was used as reference. Acetylated radiata pine wood revealed outstanding performance in colour stability and as coating substrate in all weathering trials. The performance of thermally modified pine sapwood was comparable to the unmodified reference. Its colour change was characterised by bleaching of the original dark colour. Uncoated furfurylated pine sapwood samples showed strong colour change with extensive bleaching, whereas coated furfurylated wood showed good colour stability. Coated Cr-free impregnated pine sapwood showed sensitivity to mechanical defects of the semi-transparent coating film, leading to strong discolouration. These results indicate the possible influence of preservative impregnation on coating performance of semi-transparent stains.