When your work is turning grey-ish black in your tumbler try this recipe to clean the barrel and your media: 50/50 Distilled white vinegar and water. Tumbler for 20 and rinse. Then fill with water and a few teaspoons of baking soda, tumble again for 20 and rinse. Now you are ready to use your tumbler again! My barrel is plastic, if you have a rubber barrel sometimes the cause of the grey-ish color is from the barrel itself breaking down. For that you can try tumbling with FLAT Coca-Cola for 20. It’s some kind of wizardry 😄 it’s good to regularly clean your media and tumbler to keep it working great, hope this is helpful! #tumblingjewelry #makingjewelry #tumbler #rocktumbler #jewelrytips