I tried it the other day. I used one of our normal mugs.... mostly cuz i thought it wouldnt work and it bloody worked. No now i have a random mug, which is beautifully decorated by my 3 year old.
I put it in the oven while it was cold, and left it at 200 for an hour or so then left it to cool in the oven. Gave it a right good scrub but it stayed put.
Thanks.