The cosmetic and personal care industry use crushed walnut shell media as an exfoliate in facial, body and foot scrubs. Crushed walnut shell is a hard, fibrous material that is ideal as an abrasive. The grit is extremely durable, angular and multi-faceted, yet considered a soft abrasive with a MOHS hardness of 4-5.
More aggressive formulations will use particle sizes as large as 20-40 mesh. The soft abrasive nature of walnut shell is still viable in flour sizes at 200 mesh and smaller for sensitive, fine scrubs.
The cosmetic grade of walnut shell is either ‘natural’ or ‘irradiated’ and has rounded edges (relative to an abrasive blasting grade) for a smoother feel. The irradiation process is performed with gamma rays and sterilizes the walnut shell to provide an indefinite shelf life (no micro-biological growth). ‘Natural’ product may require an additive in the formulation.