Einfluss des Hitze-Druck-Dämpfens auf das optische Erscheinungsbild und das Emissionsverhalten von Eichenholz

Influence of heat pressure steaming (HPS) on the optical appearance and the emission behaviour of oak wood.

In this work we investigated oak, which was thermal treated using two different, but common procedures: On the one hand, the oak wood was heat-pressure steamed (HPS) in an autoclave (< 2 bar and 120-140 °C), on the other hand, the oak wood was fumigated with ammoniac at room temperature. The process at high pressure and temperature can be more environmental friendly as the fumigated wood as only water is needed.
The heat-pressure steamed oak wood was investigated regarding the influence of the treatment method on the color after treatment and the color stability after artificial and outdoor weathering. The second parameter of concern was the material emissions of treated oak wood. The VOC emissions (volatile organic compounds) were measured according to DIN ISO 16000, which includes the sample preparation, the emission chambers and the measurement of VOC by gas chromatography with mass spectrometry (GC-MS) and the aldehydes by liquid chromatography and UV-detection (HPLC-UV).
Heat-pressure steamed oak and ammoniac steamed oak do not differ significantly in the total VOC emissions. However if the two procedures are compared by single components, a clear difference is visible: The main single component of heat-pressure steamed oak is furfural with a concentration of 186 µg/m³ after 28 days in the emission chamber. The most important emission of a single compound in the ammoniac steamed wood is acetamine with a concentration of 159 µg/m³ after 28 days. The formaldehyde concentrations of both wood treating procedures are lower than 5 µg/m³. During the modification treatments no formaldehyde is produced.