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 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.

It may sound odd, but plastic made of castor oil (actually, castor seed oil) is now used in some eyewear. Traditionally used as a laxative, a soap ingredient and a machinery lubricant, castor oil is also making its way into plastic auto parts, along with other non-petroleum-based plastics. Reasons for castor oil plastic development include the high price of petroleum and the ease of growing castor bean plants in places where other profitable plants don't thrive.

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.

SEE RELATED: Sunglasses Diagram

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.

Though most monel frames are hypoallergenic, it's possible people with sensitive skin may experience irritation if monel rests directly against their face. But this is preventable if the right kind of plating, such as palladium or other nickel-free options, is used.

Titanium and beta-titanium are also popular materials for eyeglass frames. Titanium is a silver-gray metal that's lightweight, durable, strong and corrosion-resistant. It has been used for everything from spacecraft to implantable medical devices 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 it's hypoallergenic.

Some titanium frames 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.

Comparison of Eyeglass Frame Materials

*Coatings and frames made of natural materials such as bone typically cannot incorporate artificial colors, patterns and textures.
 

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, also is called "memory metal." Frames made of Flexon come back into shape even after twisting or bending. 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 the world's most abundant and widely used nonferrous metal (metal other than iron or steel). Pure aluminum is actually soft and weak, but commercial aluminum with small amounts of silicon and iron is hard and strong.

Unusual Frame Materials

Want a distinctive style? Willing to pay for it? Try eyeglass frames or design accents made from these materials. High-end optical boutiques will be the best hunting grounds for this unique and sometimes pricey eyewear.

Solid silver or sterling silver is not used commonly as a principal frame material because it doesn't make very wearable or comfortable frames. Sometimes silver is used as a trace element in metal alloy frames and often provides a jewelry-like accent on plastic frames.

Some companies make gold eyewear, typically gold plating rather than solid gold. Like silver, gold can be used for accenting plastic or metal frames as well.

Wood, bone and buffalo horn frames usually are handmade, one-of-a-kind pieces. Wood and bone, though stiffer, less adjustable and much more expensive than other frame materials, are appealing because of their unique beauty. Buffalo horn frames have an elegant look and warm to your body temperature; they can feel unlike any other frame you've ever worn before.

Often used on temples or across frame fronts, leather is not as durable or practical as other materials used for accenting, but it provides an interesting and fashionable look. Recently, velvet was used to wrap a special-edition sunglass model.

Semi-precious or precious stones and crystals are sometimes used as accents in frames, especially in the temples. Popular choices are onyx, turquoise and Swarovski crystals; but even diamonds can be used for a luxurious touch. Such designs usually are worn in a formal office or on dressy occasions. Rhinestones are a less expensive alternative and often are used to create a flashy or retro look, especially in upturned "cat's eye" frames.

Are You Allergic to Your Eyeglass Frame?

Do certain frame or nose pad materials irritate your skin? Tell your eye doctor or optician, who can help you find eyeglasses you can wear comfortably. Here's the lowdown on materials:

If metal frames cause a reaction, nickel is usually the culprit because most metal frames are made of a nickel alloy. Other metals used include aluminum, stainless steel, titanium, zinc, copper, beryllium, gold and silver. Stainless, titanium, gold and silver are usually hypoallergenic.

Some people are allergic to the nose pads on metal frames. Most are made of silicone or acetate, but they also can be made of polyvinyl chloride (PVC), nickel, titanium or rubber. Silicone is tricky: certain silicones are hypoallergenic (such as medical silicone), but others can trigger allergic reactions. Both PVC and titanium are usually hypoallergenic.

Most plastic glasses are made of zyl (also called zylonite, acetate and cellulose acetate) or propionate. Other materials used in plastic frames include polyamide, nylon, polycarbonate, carbon and Optyl (a brand of epoxy resin). Propionate, polyamide, nylon and Optyl frames are all considered hypoallergenic.

Read more in our Can You Be Allergic To Eyeglasses article.

Gina White also contributed to this article.