Using a clay bar prepares a car for further car detailing that may be needed. Whether you are doing paint correction with polishing or compounding, or maybe you just applying a wax, you will be doing it using an applicator that abrades against the surface of the vehicle. If the car wasn’t clayed prior to doing those things, then very particles will still be on the surface of the paint. Therefore, doing any sort of detailing work will effectively take those particles and scratching them all over the surface of the paint. Using a clay bar (after an exterior wash), is a critical first step towards preparing your car for additional detailing work.