Backflow incense flows down through a backflow burner and creates a mist around the product. This item must be placed on a heatproof surface. When backflow incense burns the mist it creates can leave a light residue on the burner and the surface the burner is placed on. This is from natural oils and resins within the incense and can be wiped clean with a damp cloth. Never leave burning incense unattended. Our small backflow burners come with a small foam mat that the burner can be placed on when in use, however this is not heat proof so as stated above, the burner must be placed on a heatproof surface before using.