The x-1 actually pulls a LOT of chalk/dirt off the cloth. The static elec. it generates works as advertised. We have one at the 'hall and i'm amazed at how well it works. Do a couple tables and go outside and knock it on the trash can and literally clouds of chalk come off. It doesn't force dirt into the table. I think the X-1 sometimes gets knocked by those that use it wrong. You have to use LIGHT pressure and SPEED for it to work. If you push down on it too hard you never generate the static elec. needed for it to work.
That's what I'm hoping, that it really pulls a significant percentage of talk from the table.
That's it, I don't think it is like a magnet with metal.
I guess the only way to tell would be to grind up a measured amount of chalk and put it onto a similar fabric and then measure how much is left over.
Sounds I like a project for Dr dave. That poor godlike man...!