First, Organic adhesion. Organic matter mainly comes from the following aspects:
1. Food residues, insect corpses, etc. floating in the air
2. Organic ingredients in stone glue
3. Stone surface decoration, such as wood, cardboard, etc.
4. Deposits close to the stone
Second, wet. Needless to say, there are too many reasons for humidity, such as humid air, wet stone, water leakage, and rain.
3. Suitable temperature. Most molds grow in warm and humid environments, and molds are not easy to grow in cold or too hot.