Choosing a pair of lightweight and durable sunglasses can definitely protect your eyes in the scorching summer and add a stylish touch to your look. So, what materials should we choose for eyewear lenses? As a professional eyewear supplier, please allow us to briefly introduce several lens materials.
Lens Materials:
Resin: Common types of resin include PC lenses and regular resin lenses.
PC Lenses: PC stands for polycarbonate. Polycarbonate is 57% lighter than glass lenses and 37% lighter than regular resin lenses. It features high toughness, hardness, and shatter resistance, making it ideal for active children and athletes. Additionally, its high refractive index allows PC lenses to be made very thin. What’s more, PC lenses inherently block UV rays—unlike glass, they don’t require a coating to provide 100% UV protection.
However, PC lenses have drawbacks: their strength is lower than glass, so they are not wear-resistant and require a coating for long-term use. They are also softer than glass and prone to deformation under pressure, making them unsuitable for hand-made acetate eyewear or rimless metal eyewear. Their high refractive index also results in a low Abbe number (around 32), leading to significant dispersion.
CR-39 Lenses: Regular resin lenses typically refer to CR-39 resin lenses from the United States. They have a high Abbe number (low dispersion) and a slightly higher density than PC Lenses, but are still much lighter than glass and shatter-resistant. Even if they break, they don’t form sharp edges. Their refractive index is relatively low (around 1.5), so the lenses are thicker.
Glass Lenses: Glass was the earliest material used for eyewear lenses. It is hard, resistant to deformation and discoloration, and less prone to scratching than PC or resin. Its refractive index can be adjusted by adding different substances; ordinary glass lenses have a refractive index of approximately 1.523.
The disadvantages are that glass lenses are heavy—almost twice the weight of resin lenses—and fragile. If they shatter, they can easily scratch the eyes. For these reasons, glass lenses are now rarely used, replaced by resin lenses.
MR Lenses: MR lenses are high-refractive-index materials with the most balanced performance indicators, especially suitable for eyewear production. They are lightweight, provide clear vision, have high pressure resistance, and are less likely to break. Most importantly, they resist yellowing better than ordinary lenses, maintaining clarity and brightness over time, and have excellent corrosion resistance.
Nylon Lenses: Nylon lenses represent relatively new technology. They offer physical strength close to PC and optical performance similar to CR-39, with low weight, making them an ideal lenses material. However, they are more expensive than PC lenses.
Lens Coatings:
All lens materials have drawbacks, so coatings are applied to improve their optical properties.
By Function: Common coatings include hardening coatings, anti-oil coatings, polarizing coatings, anti-UV coatings, and multi-layer coatings combining multiple functions.
By Color: Coatings are mainly green, blue, red-green, etc. The color of the coating has no specific correlation with its function, so there’s no need to focus on it.
Blue is a cool tone, red is warm, and green is neutral. Psychologically, people tend to adapt better to green coatings, making green-coated lenses feel more comfortable (though this is purely a psychological effect).
Hardening Coatings (Scratch Resistant Polymer): These reduce the risk of lens scratches. Glass lenses generally don’t require a hardening coating, but resin lenses must have one.
Anti-Oil Coatings: These not only reduce smudges on the lens surface but also repel water, fog, dust, oil, and other contaminants.
Anti-Reflective (AR) Coatings: Applied to the side of the lens closest to the eye, these prevent ghosting by reducing reflections from light entering the back of the lens. They channel light from the back to the front of the lens, minimizing reflection interference and significantly improving visual clarity, with noticeable benefits for wearers.
While some coatings harden the lens surface, they remain delicate and require careful handling. All coatings have a lifespan; if a coating is damaged, the lens is essentially ruined.
UV Protection:
UV (ultraviolet) protection is a must for sunglasses. It is unrelated to lens color or light transmittance and is typically achieved through coatings. Common labeling methods include:
“UV400”: Indicates the lens blocks UV rays and visible light with wavelengths below 400nm. A lens is considered qualified if it transmits less than 2% of UV rays.
“UV” or UV Block)”: Indicates the lens blocks UV rays with wavelengths below 380nm. A lens is qualified if it transmits less than 2% of UV rays.
“100% UV Absorption”: Claims to absorb 100% of UV rays. In practice, a lens is qualified if it transmits less than 0.5% of UV rays.
SHMC Lenses: means the lenses with Super Hydrophobic coating + AR coating + hard coating anti scratches polymer.
As a professional eyewear supplier, we are specialize in acetate eyewear and metal eyewear and buffalo horn eyewear.