The object of tree pinning, as in tree-spiking, is to dull expensive saw blades, thus increasing the cost of milling trees into lumber. Where tree spikes are made out of iron or steel spikes, tree pins are made out of ceramic or rock.

To pin a tree, a hand-powered drill (called an auger) is used to make a hole in a living, standing tree about one inch in diameter and four or five inches deep. Into this hole is placed quartz rock, or a ceramic pin that has been kiln fired to "cone 10" hardness. The hole is then filled with a silicon adhesive, and masked with a piece of tree bark.

Pinning trees to dull mill blades is a form of monkeywrenching, and it has been deemed eco-terrorism or ecotage by lumber companies and critics of the practice.