Frame materials
There are many materials for frames. We can classify them into three large groups:
Materials of natural origin
a- Acetate (cellulose acetate): the raw material comes from cotton. It is the most common because it is strong, lightweight and resistant. It is manufactured in plates. It can be done in many colors, just as combined. If it is polished, it has a very nice shine.
b- Wood: There are many different varieties, achieving an aesthetic characteristic according to origin. Thus, it can come from several trees: walnut, cherry tree, maple, pear tree, palisandro, bubinga, bamboo, ebony, zebra, beech, .. It is very pleasant to the touch, but is more fragile.
c- Buffalo horn: only in very exclusive luxury brands. It is for assemblies made by hand. It is very solid and lightweight, but it needs special care because, as time passes, it stirs
Synthetic materials
a- Polyamides: is a thermoplastic resin mixed with nylon. It is flexible, solid and resistant, but at high temperatures it is wrinkled. This group belongs to the SPX (own material of a high-end manufacturer), the TR-90 and TR-100 (very sold at the moment). Grilamides, glyamides and trogemides are used for the manufacture of envelopes, made from molds.
b- Epoxy resin: it is a solid material, lightweight, with memory. The Optil is best known, used by one of the most renowned Italian manufacturers.
c- Propionate: it is a thermoplastic derivative of nylon that is injected into molds of steel to make the shape of the frontal of the frame. It is used in first price frames.
Metallic materials
a- Titanium: it is lightweight, hypoallergenic, flexible, very resistant, anticorrosive. Very apt for sunglasses in the air. Also, it can be found in beta titanium form to reduce it (75% titanium plus other metals).
b- Berilium: it is lightweight, strong, flexible, resistant to corrosion and cheaper than titanium.
c- Aluminum: it is resistant to corrosion and lightweight. It has to be combined with silicone and iron to be hard and tough.
d- Stainless steel: it is an alloy of chrome and steel. It is anticorrosive, light and strong. It does not usually carry nickel to prevent allergies.
e- Monel: it is a very common material. It is an alloy of different metals. At present, they do not contain nickel.