The Timber Resistograph is a high-resolution drill that measures the correlation between the measured values and the density of the penetrated wood. This can be used on various timber substrate, such as column, wall and on tree barks.

The Timber Resistograph detects the internal condition of the timber substrate, detecting rot, hollow areas, termite attack damage and other deformities which may not be visually seen. With a thin needle penetrating into the timber substrate, the electric power (amplitude) used to drive the needle is recorded and this shows the condition of the substrate. The more electric power consumed signifies denser and good condition timber substrate. Lower electric power consumed signifies lower density and probably poorer condition of timber substrate.