Cr-39 refers to the material that is used to make the majority designate lenses. It is an optical grade plastic polymer recognised for its light weight, chemical resistance properties and 'tint-ability'. In comparable prescriptions it is practically half the weight of glass lenses, while being slightly thicker. Its impact resistance is greater than glass but does not rise to the level of polycarbonate and it should not be carefully for applications where impacts are prevalent. On this basis, it is not recommended for active sports and motorcycling. It is more scratch defiant than polycarbonate, but will scratch if not properly taken care of.
[b]Lens[/b]Polycarbonate is an impact defiant material. It is becoming used more widely in up-to-date times - especially for motorcycling and performance sports. It is also used often for the glazing of rimless frames because of these properties. Although polycarbonate is impact resistant, it should not be carefully indestructible. Polycarbonate is the strongest material available and will have the tendency to break into larger pieces, instead of the Cr39's smaller pieces, and is, consequently, less hazardous. Polycarbonate is thinner than accepted Cr39.
Polycarbonate lenses are ten times more impact defiant than other plastics manufacture them highly convenient for performance sports or folk that are a limited (shall we say) heavy-handed! They offer Uv protection and stop 99.9% of rays from the sun, fluorescent lights and computer screens. Our polycarbonate lenses are supplied with a scratch defiant coating and are thinner than accepted lens and therefore more comfortable to wear.
Comparison of Lens Materials & Material Characteristics
Polycarbonate
- Strongest material for impact resistance
- Lightweight
- Can be coated for scratch resistance
- Most have built-in Uv radiation protection
Plastic (Cr39)
- About one-half the weight of glass
- defiant to solvents and pitting
- More choices for coatings and tinting
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