No eyeglass lens material - not even glass (most scratch resistant material) - is scratch-proof. However, a lens that is treated front and back with a clear, hard coating does become more resistant to scratching, whether it's from dropping your glasses on the floor or occasionally cleaning them with a paper towel. Kids' lenses, especially, benefit from a scratch-resistant hard coat.
Today most types of plastic lenses, including high-index, polycarbonate and traditional plastic materials have built-in scratch-resistant coatings. Since scratch-resistant coatings are sometimes optional, make sure your optician knows that you want them in your prescription eyeglasses.
Since a scratch-resistant coating can't completely protect your lenses from wear and tear, keep your glasses in a cushioned case, and clean them with a microfiber cloth and the cleaning solution your optician recommends.
Scratch resistant coatings are films made from diamond-like carbon and polycrystalline diamond materials. Through a process of ionization, a thin but extremely durable film is applied on the surface of the lens that protects the lens from scratching.
There are several technologies used to apply these coatings.
Application Methods :
- Spin Application - Spin coating is a procedure where a liquid coating is dropped on the center of a lens surface, which is then rotated at high speed in order to spread the coating, forming a uniform thin coat.
- Dip Application - Unlike spin coating, in a dip coating process the lens is entirely dipped is entirely dipped in a bath of coating solution under control conditions forming a uniform thin film coating on the lens surface.
Curing Methods :
- UV Curing - In the UV curing process, Ultraviolet Light (UV light) interacts with the lenses coated with scratch resistant formula to impart durability and desired scratch resistance.
- Thermal Curing - In the thermal curing process, the coated lenses are cured in an oven under controlled thermal conditions to impart preferred scratch resistance properties.
