Large amounts of charred residue on the radiant glass panels cause it to retain heat beyond its specified tolerance, causing it to crack or break. It is inportant to remove this residue prior to each use. Use large scraping razor only when the glass is cool. Remove the cooking grids and scrape the charred residue off the glass into the drip tray. Then wipe off any remaining dust or grease particles with a damp paper towel or cloth. No other cleaning of the glass is needed to ensure its proper function.