wifehatescar: I think we're both right. Yes, apparently there are abrasives but they are micro-fine and, according to this exerpt, should not scratch and/or marr the paint. Hobbiest detailers should stick with fine and medium grade clay, course grade clay should be left for the pros.
I found this info in the "How To Clay" article at autopia car care, there was no author:
"CLAY SAFETY
Detailing clay isn't new. Paint and body shops have been using it for years to remove paint overspray. Clay is fairly new to the car detailing market, and is very new to the consumer on retail shelves. In the early days there was always a concern that paint damage might occur if improperly used.
New technology detailing clay bars are made of fine polishing particles in a soft, malleable "clay" medium that allows the bar to be formed and kneaded. Some clay makers add color to make the bar more attractive or to identify bars of differing strength (coarseness).
Many clay products claim to contain no abrasives. This is stretching the truth. The reason clay manufacturers claim their products don't contain an abrasive is because the general public thinks the word "abrasive" refers only to aggressive, paint removing materials. The fact is that the abrasives in most automotive clay products are so fine that you will not see any reduction in paint gloss. After several uses, paint luster may even improve.
Still, I have heard some horror stories about people ruining a Ferrari paint job using a clay bar. I can see how this might be true if an inappropriate product was used or if the clay bar is used incorrectly."
I wonder if the "new technology" clay products referred to are the poly-clays marketed by Pinnacle, Wolfgang, Blackfire & others mfgs. Are these the products that contain micro-abrasives? Perhaps ClayMagic is just clay and is virtually non-abrasive.