HOYA Clear-it anti-fog wipes Wash the lenses carefully before application to prevent scratches. Use the Clear-it anti-fog cloth to rub both sides of the lens 5-10 times, or breath directly on the lens and wipe. Each cloth can be used approximately 60 times, but this also depends on the size of the lenses. The lenses will stay fog free for approximately 72 hours if humidity is around 60, but it will last for at least 24 hours. The cloth is non-washable.