Brake fade is the reduction in stopping power caused by a buildup of heat in the brake pads.  The pedal will feel the same as before, but the vehicle will not decelerate as quickly as it previously did.  Compounds are held together by resins; these resins can revert to gas when high temperatures are reached.  When this happens the brake pads can “aquaplane” on a film of gas created by the overheated resins.  This is NOT to be confused with a “soft” or “spongy” pedal.