As brake blocks are used, they get hot and lose Coefficient of Friction (CoF). With continuing use, most woven oilfield brake blocks will continue to lose CoF until they can no longer hold. If force is continually applied to the blocks at the point of almost complete loss of CoF, most blocks will “glaze,” meaning the surface of the block has been burned. This burning of the surface will not impede the future performance of the friction material if at this point the block is allowed to cool. If use continues past this point and the blocks are not allowed to cool, the block surface can get burned to a point beyond which the CoF WILL NOT RETURN. This “complete loss” of CoF has been DESIGNED OUT of the blocks American Friction supplies to prevent this from happening.