How does Neoceram or Pyroceram stand up to smoke build up? Will the smoke turn it black quickly?

There is nothing special about Neoceram or Pyroceram that will prevent it from becoming stained by heat or buildup inside your woodstove or fireplace. If you are having problems with the glass staining, you should consult with a local stove or fireplace shop to discuss possible culprits such as the type of wood that is burned or whether or if the woodstove or fireplace requires cleaning or other maintenance.