I have a new BK Princess insert I have encrusted with creosote from burning wet wood when I first started collecting wood. Rubbing wood ash on the glass door only goes so far.... I once read about folks using a razor blade on the tough stuff. I'm a little leery of doing this with my first stove. Has anyone done this? Results?
Even burning great wood will result in a dirty glass once you dial it down. I can't remember the last time I cleaned mine, once I start burning hot fires it'll stay clean enough. 
) and spoke to Chis their VP. He stated the Rutland stuff is good, but to be sure to remove it all before firing up the stove as it can etch the glass. He said that the Princess and King have large fireboxes and when you set the fire back so far, plus low and slow burning you are bound to gunk up the glass... but we all know that. he says a razor blade can be used as well so long as you don't nick the glass. He said he's not worried about the Rutland product damaging the CAT with a small amount of residue, the CAT damage is overwhelmingly from untight door seals.