Hey guys. I had the same question when my RC-4 handles got blackened by some of the leather treatment in my sheath. I asked the sheathmaker, Reid, from Sharpshooter Sheath Systems about it and he suggested I just take some warm water and maybe some mild soap and clean it off. I did this with a toothbrush and it worked like a charm. It seems that because the handles are textured they absorb oils from your sheath, hands, etc. BUT, they are essentially plasticized cloth (right?) so they shouldn't really absorb anything. Anyway, it worked great for me. Once they dry they should look like new! If you try cleaning them please let us know how it worked out. I'd be interested to see if it was the same problem. :thumbup: