Here's why:
* Evaporation: Hair gel contains alcohol and water, which evaporate over time when exposed to air.
* Oxidation: The ingredients in hair gel can react with oxygen in the air, leading to changes in their chemical structure and potentially making the gel less effective.
* Contamination: Leaving the lid open exposes the gel to dust, dirt, and other contaminants, which can affect its quality and potentially cause irritation.
To prevent your hair gel from drying out, always close the lid tightly after each use.