Placed pizza stone in 525f oven to preheat. Smoke pouring out. Opened window, exhaust & even the bathroom exhaust. Thought it would quit eventually. Put pizza in oven for approx 8 min. Smoke still billowing... removed pizza with stone. Stone as black as charcoal. Inside of oven, including window on door, soot coated everything. Pizza turned out great! Read on Pinterest & other sights, to put stone in oven on self cleaning cycle would work. Was going to shower when I saw blue flames through the oven door. The damn stone was on fire! Shut the self cleaning cycle off. Scared the crap out of me! What happened?
You can usually scrub it off with steel/copper wool or some other soft abrasive. You're likely just burning off stuff that got stuck on it. Honestly, if its not flecking off with your finger, you can just cook with it. avoid water however