Has anyone used the christensen sculpting stones? I roll the coat of a schnauzer with natural ears and I always have a problem getting a clean look at the base of the ears. I ordered some of the sculpting stones but I am not sure if I am using them correctly. If you use them like a grooming stone- not much happening, but if you use them more like a stripping knife they seem to work better. I'm sure they would be really good- but my technique seems to be lacking at this point. Does anyone have any experience with these?