Since we have covered the functions of the eye the next best topic would be how frames for eyeglasses are made. Since there are a variety of styles and materials we’ll start with plastics and continue on with other materials in a latter article.
To achieve a variety of colors opten times a plastic known as zyl (zylonite, or cellulose acetate) is the material of choice. Zyl is a very cost-effective and creative option for eye wear and is extremely lightweight. Laminated zyl is becoming popular because of the fact you can make frames that have layered colors. Frames with light colors on the interior sides can help to make your eyewear “disappear” from your visual field when you wear them. All-black frames on the other hand, will be 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 that it must be lightweight, 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 sunglass styles, as well as other shapes that can be difficult to produce.
Plastic made of castor seed oil is now used in some eyewear. Traditionally used as a laxative, a soap ingredient and 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 and aging and exposure to sunlight decrease their strength slightly and make them brittle. Color can fade over time, but not as much with modern materials.
Here’s a fun little video of the production of the plastic materials frames are made from.
At Schmidt’s Optical and Hearing™ in Stuart FL. we carry a large selection of plastic frames to fit anyone’s face or budget.. Come in today and let one of our qualified opticians help answer all of your vision questions.