For rusty steel, I use Black Beauty available at most atuo parts stores and places that rent blasters. Comes in 3 grits and the coarse is very aggressive. Wouldn't recommend it for chrome. On the backs of the bumpers, I use 120 grit glass bead, leaves a nice finish but will riun the polished surface so tape it off securely. It's also great on cast aluminum. You might try walnut shells on polished chrome, I use it on diff gears and engine parts, pretty gentle stuff. There's a guy on ebay that sells any quantity and the prices are good, even with shipping.