Fireplace buildup is a common problem that can be caused by the accumulation of SOOT, which is a black or dark gray powdery or flaky substance made up of amorphous carbon particles. SOOT is created when fuels such as wood, coal, oil, and gas are burned incompletely. It can accumulate in the chimney, on the walls of the fireplace, and on the surrounding surfaces, leading to an unsightly mess and potentially hazardous conditions.