When the rocks in the stove are heated, the smoke from the burning wood circles in the room before escaping through a vent in the ceiling or through the door left ajar during the heating of the sauna. The smoke blackens the room with soot (the floor and the sitting platform are washed before bathing begins) and leaves a pleasant aroma in the sauna. Note that the soot is not dirt but quite contrarily a form of charcoal and has the effect of resisting bacteria.