Lee
You can only chemical etch the surface providing that the surface is either sealed, factory finished with a sealent of other liquid coated or polymer type finish, varnished stained or such like, the no sanding prep is what the retail name is called i was very sceptical about this at first until i went on the course, and was still sceptical about it after the course until we performed trials on many surfaces, the product works and that is all i can say,
regards Dave ADL