Did you know only certain lens materials can be certified for use in prescription safety glasses?
The optical properties of crown glass cannot be beaten but unfortunately glass will never be used in safety glasses due to its poor performance under impact testing. When a ball bearing is fired at a lens at 45m/second the only optical materials that can withstand this impact are polycarbonate and trivex.
Both materials offer excellent impact resistance but trivex offers the superior optical properties over polycarbonate despite being slightly thicker. Trivex is also solvent resistant unlike polycarbonate. Sometimes manufacturers call these materials different proprietary names which can be misleading. Trivex is also known as Trilogy and Phoenix, whereas polycarbonate can be known as Airwear, PC or polycarb.
Below is a guide to markings on all safety eyewear.
Personal eye protection AS/NZS 1337:1.2010. Also AS/NZS 1337.6 2012 Prescription
Eye protection for occupational applications.
Lens marking must include:
- The manufacturer’s name or identification.
- Ocular marking.
- Other appropriate markings.
I or F. Medium energy impact, resists a 6 mm, ball at 45 m/s.
V or B. High energy impact, resists a 6 mm, ball at 120 m/s.
Special performance requirements:
C. Liquid droplets or splash resistance
D. Dust particles
G. Gas and fine dust particles
M. Molten metal and hot solids
I or F. Maximum protection for glasses and goggles.
V or B. Maximum protection for face shields.
If the I, F, V and B symbols do not apply to both the lens and frame, then the lowest level must be assigned to the complete protective eyewear.