[Taxvictim]

Take the duster off of the wand. I wash mine in the machine with a "natural" soap... no perfumes, dyes, or other additives. Then I let it dry naturally.

The most important thing is this: Do not use any fabric softener! Just as with microfiber towels, a fabric softener works by adding a substance to the material, and that substance will scratch your paint.

ETA: This is from the Autogeek website:

Care and Cleaning: The California Car Dusters work best when they’re dirty. Just shake them out before and after each use. Should your duster ever become so dirty that it requires an actual cleaning, just wash it in cold water with a mild detergent (like Woolite) and let it air dry.