● Waterproof eyeliner works when formula and application are right. ● Waterproof eyeliner resists water, sweat, tears, and humidity. ● Oily eyelids can still break down waterproof makeup. ● Clean, dry lids improve wear time. ● Thin layers last better than heavy lines. ● Proper removal prevents irritation and residue. ● A waterproof eyeliner pen is practical for daily precise makeup.