The term 'Flue Deposit' refers to the accumulation of SOOT and creosote in a chimney or flue. SOOT is a black powdery or flaky substance composed of carbon particles that is produced by the incomplete combustion of fossil fuels such as coal, oil, wood, and gas. Creosote is a dark oily liquid that is produced when wood is burned and is composed of tar and other organic compounds. Both SOOT and creosote can accumulate in a chimney or flue and form a flue deposit.