Natural surface inactivation of Scots pine and Norway spruce evaluated by contact angle measurements

Pinus silvestris

) and Norway spruce (Picea abies). Contact angle measurements, determined as constant wetting rate angle values (cwra), were performed on tangential and radial surfaces of planed and sawn specimens at different times after the surfaces were machined.

Contact angle curves for planed pine and spruce follow a general pattern with a linear increase for 4–6 days, i.e. a linear reduction in surface wettability, after which the curves level out. On sawn surfaces the reduction in wettability starts first after 4 days.