This material is composed of sand and chemical elements that constitute traditional glass. Its principal properties are an excellent optical quality and good scratch resistance. Thus, nearly 92% of the light is transmitted by mineral glass. It's main disadvantage are it's increased weight but its major defect lies in its low impact resistance and the fact that it fractures into several small pieces that could damage the eye.
CE STANDARDS EN 166 Lens markings LOGO 1S CE
CR39 (Plastic)
CR39 is a plastic resin. Its advantages are impact resistance, it is 50% lighter than toughened glass, less resistant to chemicals but they absorb more ultraviolet rays. On the other hand, they can scratch easily, to prevent this an antiscratch coating is applied as standard. At equal power they are thicker than glass lenses. An anti-reflection coating is less effective there than on a glass lens.
CE STANDARDS EN 166 Lens markings LOGO 1S CE
Polycarbonate
The principal characteristic of polycarbonate is its shock resistance. This lens material is the most impact resistant by far. Polycarbonate is 10% thinner than glass and 15% thinner than the plastic lenses. But like plastic it is soft and can scratch very easily, a scratch resistant coating is applied as standard. This material is particularly recommended in areas where high impact protection is required. Polycarbonate has also the advantage of absorbing all ultraviolet rays up to 380 Nm (100%).
CE STANDARDS EN 166 Lens markings EN166: LOGO 1F CE
EN166: 1 : Continuous work S : Extra strong, resists a 22 mm 43 g ball falling 1,30 m F : Low energy impact, resists a 6 mm 0,86 g ball at 45 m/s
