Industrial Mineral Supply crushed walnut shell media is a natural, soft abrasive made from California English walnut shells, screened to size and packaged at our shop in Griffith, Indiana. We've run a commercial blasting and coating operation for years and this is the same walnut we use on our own jobs. Walnut shell is the standard choice when you need to clean without damaging: carbon buildup on intake valves and pistons, paint and grime on aluminum and brass, old finishes on wood and fiberglass, and case cleaning for reloaders who want bright brass without the mess of wet tumbling. It is 100% crushed walnut shell with no plastics or additives, non-toxic, and can be reused many cycles before it breaks down into dust. Choosing a grit: 12/20 Coarse cuts fastest — use it for cabinet blasting, walnut blaster machines and heavy carbon. 18/40 Medium is the all-purpose size for brass tumbling, deburring and light blasting. 35/60 Fine is for polish cycles, rock tumblers and jewelry. 40/100 Extra Fine gives a final dry polish and works as a dense craft filler. Available in 5 lb (4.5 lb for fine grits) resealable jars and 15 lb bulk boxes. If you're not sure which grit fits your job, message us — you'll get an answer from someone who blasts for a living.