I have a bluestone paver as a cap over my chimney. The single-wall liner is in a tile-lined masonary chimney. The distance between the top of the liner and the paver is about six inches. Is this enough clearance? I've noticed black on the underside of the bluestone, and what appears to be drips of black tar? Is this bad gooey creosote? The wood I've been buring the last three weeks is underseasoned, I am sure. It hisses quite a bit. But I try to burn a really hot fire with small splits once a day for 45mins or so. Does this help? Also, do any of the anti-creosote products on the market really work? Thanks!