walnut shell blasting media is great for rust- free paint removal from sheet metal and for cleaning engines and transmissions.Walnut media blasting walnut shell blasting media is great for rust- free paint removal from sheet metal and for cleaning engines and transmissions.Walnut media blasting is especially effective when you want to clean paint, grease and other dirt from the surface of a material but maintain the integrity of the substrate materials. Ideal for use with aluminum, brass and sheet metal. Ideal for cleaning aluminum and brass