OK I'm sure this has been answered somewhere on the sight, but I can't seem to find the info I need. I am burning a Hearthstone Tribute and the glass is dirty. :blank: Not really dirty, just what appears as a brownish film. (The top inch or so is clean all the way across the top of the glass)I have the top temp at 400 (maybe not quite) (I am measuring with a stove pipe thermometer laid on the front center stone) with the air wide open, and it just wont clean off. How hot do I need to burn for the air wash to kick in and clean my glass?