A yellow oil rendered and purified from the feet (but not the hooves) and shin bones of cattle. It remains liquid down to a low temperature, and is used as a conditioning, softening and preservative agent for leather. In the 18th century, it was also used medically as a topical application for dry scaly skin conditions.
Neatsfoot oil remains liquid at room temperature because the fat in animals' legs generally has a lower melting point than the body fat. This occurs because the legs and feet of such animals are adapted to tolerate and maintain much lower temperatures than those of the body core, using countercurrent heat exchange between arterial and venous blood. Because of this, neatsfoot oil remains liquid at room temperature and so can easily soak into leather.
Caution: Oil may permanently darken light colored leathers. Do not use on suede leathers.