We are removing the old linoleum floors from the 1910 victorian we just bought and ran into a problem with part of the floor. In one room, there is what seems to be about 1/8" thick tar paper, or some type of thick, fibrous material glued down between the hardwood underneath and the tiles we took out. Any advice on how to remove the tar paper? We've tried mineral spirits & paint thinner w/ no luck. A heat gun works, but is quite laborious and we are worried about the fumes. Plus it sets off the smoke detectors every few minutes. Thanks!