On whether glycolic acid can expire
Glycolic acid is also a chemical thing. Today everyone doubts whether it can expire, which is a matter of practicality and safety.

View of the properties of chemistry, the change of substances, often depends on the environment. Glycolic acid exists in the world, under conditions of light, heat, and humidity, or chemically changes. Light can promote the movement of its molecules. If it is exposed to strong light for a long time, it may change its structure and cause its properties to change. Heat is also the main cause. At high temperatures, molecules are active, or they may decompose, polymerize, etc., which will damage their original characteristics. As for moisture, if water vapor comes into contact with glycolic acid, or the reaction of hydrolysis, it will change its composition.

And look at the methods of preservation. If properly sealed, in a cool, dry, dark place, glycolic acid may last for a long time and its properties are also stable. However, if the seal is not good, the gas can enter, the dust is mixed, or the microbial growth can cause it to change qualitatively, which is like an expiration date.

Furthermore, it depends on the needs of the use. In the field of medicine and beauty, glycolic acid is used, and its quality is pure and its properties are stable to severe. If it expires, it will be harmful to the human body, such as skin allergies, damage and health. In industrial use, the quality change may also lead to production errors and poor products.

From this perspective, glycolic acid can really expire. The reason for its expiration, the environment, preservation, and the duration of use are all involved. It is the user who should carefully observe the condition of its existence and follow the regulations to ensure its quality, avoid the trouble of expiration, and use it appropriately.