What is Creosote?
Black residue, ranging from sticky to glassy, that coats the inside of a chimney flue as wood smoke condenses on cool walls. It progresses through three forms: dust at Stage 1, a crunchy layer at Stage 2, and hard glaze at Stage 3, which is the form behind most chimney fires. An annual sweeping clears Stages 1–2; removing Stage 3 takes restoration.
