I have a woodburning stove, and a couple of weeks ago I put three bits of old fence post on the top of the fire to help them dry out, as they had been outside. I now have three burn marks on the top of the stove. I think it must be that either some wood resin or some sort of stain / varnish came out of them when they got hot.
Have tried cleaning it with the ammonia stuff they gave me to clean the door, but no luck.
Any ideas?