What is the purpose of lip liners? Are the lip crayons kids color their lips with What about grown-ups? Does someone want to paint their lips some eye-popping neon color so that people can see their lips from miles away? This would be really strange if someone wanted to do this. But in reality, there are some purposes for using a lip liner. And there are specific characteristics that make one lip liner stand out over another one. Customers have specific requirements they expect a good lip liner to have before they will invest their money in the lip liner. They may want to enhance the natural color of their lips without painting lipstick on them. Some people prefer a natural look over a cosmetic look.