Provide in one embodiment is an apparatus, comprising an indentor wherein a tip thereof is configured to engage a sample surface, a surface-referencing device configured to establish the position of the indentor relative to the sample surface, a drive mechanism configured to move the indentor along the sample surface to form a scratch, and a measurement device configured to measure at least one of (i) a pile-up height of sample material removed from the scratch and (ii) a width of the scratch.