If your vehicle has been exposed to a ferrous dust environment, Q²M Iron is the safest way to remove chemically this type of contamination. Spray all over the vehicle, let it react for 3 to 5 minutes but don't let it dry. Rinse heavily & inspect. Re-apply if needed. If the contamination is still present afterwards, you might have an oxidised panel, meaning you paint does not anymore protect the body of your car, therefore you'll need to visit a bodyshop.
