This does work, though it can also roast you out if it's not that cold outside. You can always open a bunch of windows and burn it on high for a bit. Black glass doesn't really hurt anything. There's normally no flames to watch anyway. The bigger issue is that if your glass is black it probably means that your chimney is as well. Heavy amounts of creosote can lead to other problems, such as chimney fire or reduced draft, which can lead to smoke backing up and more black glass! I would clean the stove and chimney thoroughly, including the glass. Your stove dealer can sell you special stove glass cleaner, or you may find it at Home Depot. When you light a fire, do burn it on high until it is going good (if you have a stove top thermometer, it should be near maximum...open a window if you have to) before turning it down. Then turn it down in increments, not all at once. Again, when you add wood, let it burn on high at least a few minutes until the new wood is burning good. One last thing, wood that isn't dry enough can create more black glass and creosote. Try to use wood that has seasoned at least a year or longer after being cut. If not possible, you are just going to have to clean chimney and glass more often. Good luck.
