Werm said:I've found that if the glass is fairly dirty you can use a razor blade type scraper to get you through 'till you can give it a proper cleaning.
-just my .02!
This works but can damage the surface of the 'glass' after doing it for years and the glass gets hazy.
Cooled enough to to clean and refired. Now that I'm using better wood it keeps itself clean. But that worked for me... Piping hot I was afraid of cracking it by cooling it in one area too fast.