Tianqidan emulsion bottle mouth is moldy.

It has deteriorated. According to Baidu Encyclopedia, the reason why the emulsion bottle mouth is moldy is that the place where it is placed is too wet or the temperature is too high, which leads to the deterioration of the ingredients. Be sure to tighten the cover in time after use to prevent air from entering. Many cosmetics are not added with antibacterial agents, and some substances in cosmetics contain starch, protein and sugar, which just provide nutrient solution for molds, leading to moldy products.