That’s a really good question! It’s hard to say! First off, I would say try it and see what happens! If that’s a little too adventurous for you, contact the manufacturer and ask about this. Since most of these items are toys, the motor tends not to be strong enough to handle heavy clay.  But, it is a good idea to use this clay to show your child what the process is like when you become a “real potter!” This is especially the case, since the size of these wheels is so conducive to their small hands. One other issue you might have is using some of the light plastic sculpting tools on heavy clay--they might not cut it, so to speak!