Faanyag rostirányú tömörítésével kapcsolatos elméleti és gyakorlati kérdések áttekintése - 1. rész: az alapanyagok és előkészítésük, a tömörítés elmélete

Abstract

The purpose of the longitudinal compression of wood is to make it bendable. Several factors influence the outcome of compression (wood species and quality, moisture content, temperature, compression rate, etc.). Most hardwood species with initial moisture contents above 20% can be compressed. The wood is normally softened by steaming and, during the process, kept at a temperature above 80 °C. While compressed in fibre direction it needs to be restricted within the compression chamber to prevent the wood from suckling. Frictional forces need to be minimized so that the transformation is performed at even rate. The middle lamellae, mostly consisting of lignin and hemicelluloses, are softened by thermo-hydro wood processing, allowing of the wood fibres with high cellulose content to slip during compression, and the longitudinal cell walls crinkle. Consequently, the elasticity of the wood decreases, thus it will be much easier to bend, even when dry and at room temperature.