Although frame styles are what get the most attention in when it comes for fashion and purchasing tips on sunglasses, there are many types of lenses as well. In this post, we’ll give you the rundown of anti-scratch and SPF, coatings, as well as mirrored, gradient, polarized, and photochromatic lenses.
The earliest iterations of sun glasses were lenseless goggles with large slats to cut glare, but nowadays, there are tons of different manufacturing techniques and coatings that can be applied to lenses to make them better at protecting from sunlight and glare. Two important coatings that are added to sunglasses are UV-blocking coatings as well as scratch-proof coatings. The former is the one characteristic we’d say to always look for in your sunglasses, regardless of what other style elements you choose. The latter is a cosmetic addition that prevents your lenses from getting marked up by nicks, scratches, or drops. While not strictly necessary, we would suggest opting for scratch-proof lenses whenever possible because it keeps your glasses looking good for longer . This is especially true when an anti-scratch formula is layered over other lens coatings, such as easy-to-chip mirrored ones.
Mirrored lenses are coated with chemicals that cover about half of the surface of the lens, but that are dispersed evenly. This means that half the light is let in while the rest is reflected away. Because the mirrored coating often covers half of the surface of the mirror, the glasses are often called half-silvered lenses. Gradient lenses often use the mirroring technique and are tinted more strongly at the top of the lens, and fade to a lighter colour at the bottom.
Whether they are mirrored or not, gradient tinted lenses are useful for anyone who wants to cut sunlight but keep as much clarity of vision as possible. With a stronger tint at the top, these glasses allow wearers who are, for example, driving, to be protected from sunlight when their gaze is on the road but can easily look down without a blurring effect. We think that these characteristics also make gradient sunglasses a great style to select for reading at the beach, park, or pool.
Polarized lenses are another type of glare-eliminating lenses, and may be even more effective than ordinary tinted lenses. They are covered with a thin layer on one side of the lens. Occasionally the film is embedded into the lens. This layer is made up of molecules that align in one direction. This results in a film that has tiny “slats” in it and functions like a screen or blinds. It prevents a percentage of light from passing through to the wearers’ eyes. Since light usually bounces horizontally, the tiny “slats” are vertical. These lenses useful because they are designed specifically to block light and not distort the wearer’s vision in any other ways (some tinted sunglasses can make everything look fuzzy or blurry). If you are thrifting for sunglasses, you might notice that vintage, retro, or gently used glasses’ lens type might not be labelled. Fortunately, there is an easy way to determine whether or not the pair of glasses you’ve been eyeing are polarized: take them into an area with some glare. Of course, all sunglasses tamp down the amount of light when you put them on. But if you turn a pair of polarized glasses sideways and peek through the lenses, these glasses will not properly cut the glare at all, because they the orientation of the tiny “slats” is now allowing the light in. This noticeable difference should let you know whether or not the sunglasses are polarized.
Some glasses change colour and darken depending on the intensity of the sunlight. This type of lens is called photochromatic or photosensitive lenses. The lenses–originally glass–were treated with a layer of molecules that react to UV exposure. When they are exposed to sunlight, the molecules change and block out some of the light. This process was originally applied to glass sunglasses. It didn’t work well on glass prescription lenses, however, so the process was altered slightly and applied primarily to plastic lenses.
What style of sunglasses will you be wearing this summer? What’s the most important thing you look for in a pair of sunglasses? Do you use your shades as a fashion accessory or do you only wear them when you need them? Let us know through Facebook or through this blog for a chance to be featured on our Facebook page.