The unsaturated hydraulic properties of core samples are highly sensitive to alterations caused by mechanical disturbance in the original coring, or in later preparatory treatments. For shallow depths (down to about 6 m), we obtain soil cores with a hand-operated, hydraulically driven coring apparatus. From greater depths, and for shallow sampling of materials unsuitable for hand sampling, samples are obtained with less gentle methods. In most such cases we start with oversized field samples and recore them in the lab. For this we use a custom-built recoring machine (pictured at left) whose electrical actuator and slow, steady speed allows the outer, more disrupted portions of the core sample to be trimmed away.