Beal Rope Cleaner
Here's what other sites are saying:
If your hands look like you've been working in a coal mine after a single belay session, it's time to give your cord a bath with some Beal Rope Cleaner. This rope-friendly detergent won't damage polyamide fibers nor will it leave a residue on the sheath.
Keep your ropes strong. Beal's Rope Cleaner is anon-aggressive detergent developed to clean ropes and Harnesses easily. It comes in a 1 L bottle.