Studies were made on the Pilodyn 6J wood tester. The (negative) coefficient of correlation between Pilodyn reading and density was > 0.9 when > 12 readings/sample were taken. The following relationships were studied: (i) density and pin penetration for Norway spruce; (ii) the angle between plane of growth rings and direction of pin penetration versus accuracy of density determination; and (iii) pin penetration versus density in oak, Scots pine, and silver fir timbers from 18th-century buildings. -- AATA