The amount of pressure exerted per unit area is critical in microwear formation. Previous researchers have incorrectly assumed that amount of pressure per unit area can be controlled by controlling the amount of external pressure [i.e., load] applied during implement usage. Research has shown that even when the external force is constant, the fracture threshold varies depending on the amount of implement edge is contact with a worked item. Since edge contact varies considerably between functionally distinct classes of artifacts, a large amount of “noise” may have been inadvertently introduced into previous experimental results. This poses a significant problem, which must be addressed by future researchers.