The frame materials used in the production of modern spectacle frames are plastic, metal, or composite (combination of the two).
Cellulose acetate (zylonite)
Cellulose acetate is the most commonly used plastic in spectacle frame production. It is an inexpensive material and is easy to work with and comes in various colours, patterns and textures. It is an easy material to adjust but one disadvantage is that it becomes brittle with age.
Nylon is a lightweight and virtually unbreakable material. Due to these factors many sports and safety spectales are produced using nylon. However it is a difficult material to adjust and is only available in dark colours. It does have the tendency to become brittle with time.
This is a hypoallergenic material which is of benefit to patients that have a skin sensitivity. It is also lighter than cellulose acetate. It is a difficult material to adjust because it can return to its original moulded shape prior to adjustment. This material can break on adjustment if it is not heated properly.
Polycarbonate material has a high impact resistance, up to 10 times that of conventional plastic. Therefore it is the preferred choice of material for children’s, sport’s and safety spectacle frames.
Aluminium is a light weight metal frame material but its has a disadvantage in that it is difficult to solder or weld and therefore not widely used.
Cobalt is usually used in a metal alloy. Usually used in high quality frames that are lightweight, flexible, durable and thin. It can be coated with various colours. It is an expensive material and therefore not used in frame manufacture very often.
Monel is a popular metal used to produce spectacle frames because it does not lose its strength even if it is hammered into various shapes. It can be made into a variety of colours.
Nickel silver is a common metal used to produce the inner core of temples, end pieces, hinges and nose bridges. It is a brittle metal and therefore cannot be used in slender/thin frames.
Phosphor bronze is a alloy made up of 95% copper. It is a flexible alloy and is commonly used in temple production.
Stainless steel is a corrosion-resistant metal, however it is a difficult metal to work with in the manufacturing process of spectacles frames.
Trilam is a very lightweight metal. However it is a memory metal i.e. retains its shape, that it makes it a difficult metal to adjust.
Carbon fiber graphite(CFG)
Carbon fiber graphite is a combination of nylon and carbon that provides extra strength for metal frames. In its natural state it is black in colour, but it is now readily available in various colours.
MXP7 is a blended nylon material used in the production of injection-moulding frames. It is a strong, lightweight and durable material. It retains its shape or form unless it is heated.
This is a proprietary material that is produced from a titanium-based alloy. It has a “memory” factor that allows it to be twisted and flexed but returns to its original shape afterwards. It is a very durable material and lighter in weight than other metal frames.
Titanium is an aerospace technology material and is an excellent material for manufacturing of spectacle frames. Titanium is extremely strong, lightweight and hypoallergenic (benefits patients with skin sensitivity). Titanium can be classified as pure titanium or beta titanium.
Pure titanium is more resistant to breakage and is not a metal alloy (in combination with other metals). The cost of a pure titanium frame is expensive because it is not a metal alloy.
Beta titanium is lightweight, corrosion resistant and very flexible due to its metal alloy composition i.e. 74% pure titanium, 22% vanadium and 4%aluminium. Usually used in making of flexible temples, profile assemblies and wire bending parts of beta titanium frames. Therefore a beta titanium frame is not made of pure titanium but of a combination of titanium and other metals, the cost is therefore less than a pure titanium frame.