Walnut shell is outer part of the walnut.The black one is of high flavor, but due to its hard shell and poor hulling characteristics it is not grown commercially for nut production.It is a hard and the chemical version of this material made from crushed walnut  It is the most common type of soft abrasive for industrial use.

This products are bio-degradable, non-toxic, and environmentally safe.It was originally developed for cleaning gasoline and diesel engines due to its lack of silicon and toughness. It will clean metals, alloys and plastics without scratching or pitting the surface.Walnut shell abrasives are specially manufactured to eliminate mineral contamination and/or metal contamination.