Soot might appear on the glass if the combustion temperature is too low, or if the air controls are used incorrectly. The secondary air controls must be set to the open position, and the primary air controls will need to be closed. The primary air intake (either from the riddling grate or air control) are only to be used during the lighting period, or when dry wood is put into the stove.
We recommend that you use wood with a moisture content of 16-20%. If you want to be sure that wood is dry enough, you can test your wood with a moisture meter.
You can clean the glass using stove glass cleaner, but this must be done when the stove is cold. You can also clean the glass window with a piece of newspaper and some warm soapy water. If heavy soot build-ups occur, you can use treble ammonia water to clean the glass.