Eye black can't be used for a long time after opening

Eye black, also known as kohl or kajal, generally should not be used for a long time after opening due to the following reasons:

• Risk of Bacterial Contamination: After the eye black is opened, it is exposed to the air and comes into contact with various external environments. Bacteria, fungi and other microorganisms in the air and on the skin can contaminate the eye black. The longer it is used after opening, the more microorganisms will multiply in it. When these contaminated eye black products are used, they may cause eye infections, such as conjunctivitis, keratitis and other eye diseases, leading to symptoms such as redness, swelling, pain and itching of the eyes.
• Oxidation and Deterioration: The ingredients in eye black may react with oxygen in the air and other substances after opening, resulting in oxidation and other chemical changes. This may cause changes in the color, texture and performance of the eye black. For example, it may become dry, hard, or the color may fade, which not only affects the use effect but also may have adverse effects on the eyes. Some components may also produce harmful substances after deterioration, which increases the risk of eye damage.
• Reduced Efficacy: The preservatives and other ingredients in eye black play a role in inhibiting the growth of microorganisms and maintaining the stability of the product within a certain period. However, as time goes by after opening, the efficacy of these preservatives will gradually decrease. The ability of the product to resist microbial contamination and maintain its original quality is also weakened, which makes it more likely to have quality problems and affect eye health.