Prepcjrotion 0' Extraded Wood Str~

The surface wettabiJity and fats of yellow bird1wood were examined in an attempt to illustrate how heat-induced d1anges in wood fats might be related to d1anges in surface wettability. A marked reduction of surface wettability accompan;ed heating of yellow birchwood. The degree of water repellency imparted to the waod was highly dependent upon heating temperature and time. Acetone extraction of wood prior to heating to 105°C prevented a d1ange in wettability and increased the surface wettability of wood heated at higher temperatures. Examination of the fats after heating indicated little hydrolysis and ~iderable oxidation of the unsaturated fatty acids and esters. The amounts of free fatty acids present in fresh, air-dried, or heated wood were far too low to approod1 amounts considered necessary to influence surface wettability. The preponderance of linoleic acid ester and its rapid oxidation suggest that oxidation products from this ester might be responsible for the observed d1anges in wettability.