An investigation of factors affecting wettability of some southern hardwoods
>Wettability of sanded and nonsanded transverse and tangential sections of 22 southern hardwood species were[was] judged by measurement of contact angles using phenol-formaldehyde resins. As expected, contact angle values on transverse sections were higher than on tangential sections for both sanded and nonsanded surfaces. On sanded surfaces, hackberry had the highest mean contact angle (64.7°), and black oak had the lowest mean contact angle (50. 1°). On nonsanded surfaces, winged elm had the highest mean contact angle (59. 1°), and sweetgum had the lowest mean contact angle (45.9°). In addition, 4 of the 22 species (southern red oak, sweetgum, white oak, and post oak) were selected to investigate the effect of ovendrying, air-drying, and freeze-drying on wettability. The mean transverse contact angle was 2.1° to 29.0° and 5.1° to 31.5° higher than radial and tangential values, respectively. The contact angle pattern typically displayed for a given species and plane was generally ovendry > air-dry > freeze-dry. The species pattern for most drying methods and planes was: sweetgum > white oak > post oak > southern red oak. White oak and post oak gave similar contact angle values.