Kinds Of Eyeglass Frame Materials

Different eyeglass frame materials greatly expand your options for a new look. While shopping for new eyeglasses or sunglasses, ask your optician for advice about variety in colors, durability, lightness, favorite brands, hypoallergenic materials, uniqueness and price. In fact, finding eyeglasses with the qualities that are most important to you could be as simple as choosing the right frame material, because each type has its own unique strengths.

Plastic

If you want the colors of the rainbow, then zyl (zylonite, or cellulose acetate) is your material. Zyl is a very cost-effective and creative option for eyewear and is extremely lightweight. Particularly popular right now are laminated zyl frames that have layered colors. Look for light colors on the interior sides, which can make your eyewear "disappear" from your visual field when you wear them. An all-black frame, on the other hand, is visible at all times on both interior and exterior sides.

Some manufacturers also use cellulose acetate propionate, a nylon-based plastic that is hypoallergenic. It's lightweight and has more transparency and gloss than other plastics. If your main criterion for a frame is lightness, then definitely consider propionate frames.

Eyeglasses made of nylon first were introduced in the late 1940s. Because of brittleness and other problems, eyeglass manufacturers switched to blended nylon (polyamides, co-polyamides and gliamides). Today's blended nylon frames are both strong and lightweight.

Nylon is also a premier material for sports and performance frames, typically made of gliamides, grilamid or trogamid materials that are very resistant to hot and cold and are more flexible, yet also stiff. Nylon also is easily molded into today's popular wraparound styles, as well as other shapes that are difficult to produce.

Plastic frames do have some drawbacks. They are easier to break than metal frames, they will burn (but are not easily ignited), and aging and exposure to sunlight decrease their strength slightly. Color can fade over time, but not as much with modern materials.

Metal

Monel — a mixture of any of a broad range of metals — is the most widely used material in the manufacture of eyeglass frames. Its malleability and corrosion resistance are pluses. Still, it is not 100 percent corrosion-resistant: for some people, monel can react with their skin chemistry. But this is preventable if the right kind of plating, such as palladium or other nickel-free options, is used.

Many frame manufacturers offer titanium and beta-titanium styles these days; titanium is a silver-gray metal that's lightweight, durable, strong and corrosion-resistant. It has been used for everything from the Gemini and Apollo space capsules to medical implants such as heart valves. Titanium eyewear can be produced in a variety of colors for a clean, modern look with a hint of color. And they're hypoallergenic. Some titanium farmes are made from an alloy that is a combination of titanium and other metals, such as nickel or copper. In general, titanium alloy frames cost less than 100 percent titanium frames.

Beryllium, a steel-gray metal, is a lower-cost alternative to titanium eyewear. It resists corrosion and tarnish, making it an excellent choice for wearers who have high skin acidity or spend a good amount of time in or around salt water. Beryllium is also lightweight, very strong, very flexible (making it easy for an optician to adjust your glasses) and available in a wide range of colors.

Stainless steel frames and surgical stainless are another alternative to titanium. Qualities of stainless steel frames include light weight, low toxicity and strength; many stainless steel frames also are nickel-free and thus hypoallergenic. Stainless steel is readily available and reasonably priced. It's an alloy of steel and chromium, and may also contain another element. Most stainless steels contain anywhere from 10 to 30 percent chromium, which provides excellent resistance to corrosion, abrasion and heat.

Flexon is a titanium-based alloy. This unique and popular material, originated by the eyeglass manufacturer Marchon, is called a "memory metal": frames made of Flexon come back into shape even after twisting, bending and crushing. Flexon frames are lightweight, hypoallergenic and corrosion-resistant. Marchon company officials describe the frame as about 25 percent lighter in weight than standard metals, giving you a much lighter feel on your face.

Frames made from aluminum are lightweight and highly corrosion-resistant. Aluminum is used primarily by high-end eyewear designers because of the unique look it creates. Aluminum is not only the world's most abundant, but also the most widely used, nonferrous material. Pure aluminum is actually soft and weak, but commercial aluminum with small amounts of silicon and iron is hard and strong.

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Glasses Frames

Frames are generally made of plastic, nylon, a metal or a metal alloy. Nylon frames are usually used in sports because they are lightweight and flexible. They are able to bend slightly and return to their original shape instead of breaking when pressure is applied to them. This flex can also help the glasses grip better on the wearer's face. Metal frames are usually more rigid than nylon frames, thus they can be more easily damaged when the wearer participates in sport activities, but this is not to say that they cannot be used for such activities. Because metal frames are more rigid, some models have spring loaded hinges to help them grip the wearer's face better. The end of the resting hook and the bridge over the nose can be textured or have rubber or plastic material to improve hold. The ends of the resting hook are usually curved so that they wrap around the ear; however, some models have straight resting hooks. Oakley, for example, has straight resting hooks on all their glasses, preferring to call them "earstems".

Frames can be made to hold the lenses in several different ways. There are three common styles: full frame, half frame, and frameless. Full frame glasses have the frame go all around the lenses. Half frames go around only half the lens; typically the frames attach to the top of the lenses and on the side near the top. Frameless glasses have no frame around the lenses and the ear stems are attached directly to the lenses. There are two styles of frameless glasses: those that have a piece of frame material connecting the two lenses, and those that are a single lens with ear stems on each side.

Some sports-optimized sunglasses have interchangeable lens options. Lenses can be easily removed and swapped for a different lens, usually of a different colour. The purpose is to allow the wearer to easily change lenses when light conditions or activities change. The reasons are that the cost of a set of lenses is less than the cost of a separate pair of glasses, and carrying extra lenses is less bulky than carrying multiple pairs of glasses. It also allows easy replacement of a set of lenses if they are damaged. The most common type of sunglasses with interchangeable lenses has a single lens or shield that covers both eyes. Styles that use two lenses also exist, but are less common.

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