Tinted eyeglass lenses

Did You Know…

…why Tinted Eyeglass Lenses Are Usually Brown, Gray, or Green?

Actually, the trendy colors for this summer are apricot, mint, citrus, and sea blue. Sunglasses are usually tinted brown, gray, or green, since these are the colors that distort color perception the least. When lenses are tinted with other colors, the brain requires a certain length of time to neutralize the color distortion from the glasses and thus perceives colors differently.

But how do the lenses actually get colored in the first place? There are very different procedures available for doing this, which depend on whether the lenses are made of plastic or mineral glass.

Eyeglass lenses – so-called mineral eyeglass lenses – are tinted by applying absorbent coatings through the process of vacuum deposition. These thin coatings consist of metal or metal oxide mixtures and can be vacuum-deposited only at certain high temperatures. They also have a high refractive index, meaning that they increase reflectance. They are deposited in multiple layers so that the properties of the glass remain intact. Due to the tinting of the metal or metal oxide mixtures, these lenses are available only in brown shades of different levels of absorption.

Almost all plastic lenses are tinted in a special dye bath. To do this, several lenses are mounted on special holders and then immersed in the bath. While the eyeglass lenses are in the immersion bath, the dye particles penetrate to about 0.1 millimeter beneath the surface of the lens and become firmly embedded in it. Each immersion basin is equipped with a magnetic agitator to ensure that all eyeglass lenses are tinted evenly. The dye substances used also have applications in the textile industry.

It is possible to match every color sample provided, tinting plastic lenses in any conceivable color and light reduction level – based on the primary colors of red, yellow, and blue. Lenses with gradient colors can also be produced with special equipment, allowing for a gradual tint transition from light to dark by subjecting the eyeglass lenses to a predetermined exchange speed. This means that it is not only possible to pick out eyeglass frames, but also the tint of the lenses, resulting in eyeglasses with a personalized optical design – even if this means that not all colors can be perceived in their original shade.

13 June 2012