Characteristics
Fat from warm-blooded animals normally has a high melting point, becoming hard when cool – but neatsfoot oil remains liquid at room temperature. This is because the relatively slender legs and feet of animals such as cattle are adapted to tolerate and maintain much lower temperatures than those of the body core, using countercurrent heat exchange in the legs between warm arterial and cooler venous blood – other body fat would become stiff at these temperatures. This characteristic of neatsfoot oil allows it to soak easily into leather.
Modern neatsfoot oil is still made from cattle-based products, but now, while retaining its historic name, usually is made mostly from lard, which is sold as pure neatsfoot oil. This formulation does darken leather. If mineral oil or other petroleum-based material is added, the product may be called "neatsfoot oil compound". Some brands have also been shown to be adulterated with rapeseed oil, soya oil, and other oils. The addition of mineral oils may lead to more rapid decay of non-synthetic stitching or speed breakdown of the leather itself.
Read more about this topic: Neatsfoot Oil