turbomangt has a website with clay info, or try
www.zainostore.com for a clay lesson. I have been using clay for several years and quite the contrary, clay prevents scratches by removing grime, dirt, rail dust etc. You only think you cleaned your car by washing alone. All the fine grit is ground into the paint, ever wonder why a new black car has no swirl marks and after a few waxes it's loaded?. Ever notice your white applicator pad turned grey after waxing, what is that grey stuff? It's dirt you failed to remove after washing that is acting as sand paper on your new black finish. I am no detailing expert but I do know what many say about clay and I have quite a bit of experience with it and extremely satisfied with the results.