Generally, the main reason for the blackening of walls is that the amount of use is relatively large, and the temperature of the smoke fire head is too high, or it is relatively inferior and contains chemical additives. Our products are made of 100% pure natural raw materials, and the proportion of ingredients is strictly controlled. Therefore, it is rare to see blackening of walls with the amount of daily incense burning at home. For situations such as temples, chapels, etc. that burns a lot of incense, please pay attention to the daily ventilation, and it will effectively delay the probability of yellowing the walls.