Agra-Grit Walnut Shell Blasting Grit is safe for you and the environment. Silica free material reduces your risk of Silicosis. Walnut Grit is softer than sand, and when used properly maintains the integrity of underlying structure. Great for removing graffiti, cleaning engines and transmissions, soft metals, prepping metal for paint, restoring historical items, etc. Less damage to the substrate means the job gets completed faster. A great non-toxic solution for your blasting needs.