Sunglass Lens Materials Compared: CR-39, PC, TAC, Nylon and Mineral Glass

Walk into any sunglass factory and you will find five lens materials in regular production: CR-39, polycarbonate (PC), TAC, nylon (SR-91 / Trivex), and mineral glass. Each has a different combination of optical quality, impact resistance, weight, and durability. For everyday fashion eyewear, the differences are largely academic. For outdoor sport eyewear — where lenses face impacts, UV exposure, sweat, salt water, and physical abuse — the material choice determines whether a product succeeds or fails in the field.

This guide explains what each material is, how it performs, and which outdoor applications it is best suited for. It ends with a quick-reference specification table and FAQ for OEM buyers.

At a Glance: How the Five Materials Compare

Figure 1 — Key property comparison across five sunglass lens substrates. Bars reflect relative performance at standard production grade.

CR-39 — Best Optical Clarity, Limited Impact Protection

CR-39 (allyl diglycol carbonate) has been the standard plastic sunglass lens since the 1950s, and for good reason: it has an Abbe value of 58 — close to mineral glass — which means colors are rendered accurately and there is virtually no color fringing at the lens periphery. It accepts dye, hard coat, AR, and polarizing film reliably, and it machines cleanly for prescription work.

The limitation is impact resistance. CR-39 does not meet ANSI Z87.1 or EN 166 impact standards at standard production thickness. A hard strike can fracture it into sharp pieces. This makes it unsuitable for cycling, ball sports, or children's eyewear — anywhere a lens impact is a realistic scenario.

• Best for: Fishing, golf, casual outdoor use, prescription sunglasses, fashion eyewear

• Not recommended for: Cycling, racket sports, children's sport, any category requiring impact certification

Polycarbonate (PC) — The Sport Safety Standard

Polycarbonate is the default substrate for sport and children's eyewear globally. It meets ANSI Z87.1 impact requirements at standard production thickness, inherently blocks UV400 without an additive, and is the lightest mainstream lens material after nylon. If your product will be marketed as sport eyewear in the US, EU, or Australian market, PC is almost always the right starting specification.

The tradeoff is optical quality. PC has an Abbe value of 30 — about half that of CR-39 — which produces noticeable color fringing at high gaze angles, particularly in prescription lenses above approximately ±1.50D. For plano (non-prescription) sport lenses, this is rarely a problem. For prescription sport programs, it is worth evaluating nylon instead.

PC also scratches very easily without a hard coat. A premium 4–6 micron UV-cure hard coat is mandatory, not optional, for any PC sport lens intended for outdoor use.

• Best for: Cycling, ball sports, skiing, children's eyewear, protective eyewear, any program requiring ANSI Z87.1

• Watch for: Hard coat quality (critical); optical distortion in high-Rx prescription programs

TAC — The Polarization Substrate

TAC (triacetate cellulose) lenses are not conventional cast lenses — they are laminated assemblies: a PVA polarizing film sandwiched between TAC layers, with functional coatings applied to the front and back. The polarization is built into the structure, not applied to the surface. This gives TAC lenses consistently high polarization efficiency (≥99% under ANSI Z80.3) and makes delamination much less likely under field conditions than surface-applied polarization on other substrates.

TAC is the standard substrate for fishing, marine, and driving sunglasses globally. Its Abbe value (~48) is lower than CR-39 but well above PC, and tint is perfectly uniform across the lens area regardless of thickness.

For saltwater environments, the standard TAC coating stack is not sufficient — a marine-grade fluoropolymer topcoat validated to ISO 9227 salt spray is required to prevent edge delamination and surface degradation.

• Best for: Fishing, marine / watersports, driving, any polarized sunglass program

• Watch for: Specify marine-grade topcoat for saltwater use; standard TAC coatings are insufficient for sustained salt exposure

Nylon / SR-91 — The Premium Sport Choice

Nylon-based lens materials (sold commercially as SR-91, Trivex, and related variants) are the premium tier of sport substrates. They combine the impact resistance of PC with substantially better optical quality — Abbe values around 43–47 versus 30 for PC — and are the lightest commercial sunglass lens material at approximately 1.11 g/cm³.

For endurance sports like running and triathlon, where frame weight matters over hours of wear, the weight advantage over PC and CR-39 is genuinely meaningful. For prescription sport lenses, the optical quality improvement over PC eliminates the color fringing that is the most common optical complaint in PC prescription programs.

The practical limitations are cost (typically 30–50% above PC) and a higher minimum order quantity. Nylon also requires a good hard coat — its uncoated surface scratches more easily than CR-39.

• Best for: Running, triathlon, cycling (prescription programs), premium sport brands differentiating on optical quality

• Watch for: Higher MOQ; confirm hard coat compatibility; budget for unit cost premium over PC

Mineral Glass — Optical Excellence, Sport Liability

Mineral glass offers the best optical quality and the best scratch resistance of any sunglass material. It does not craze or warp with temperature, holds dimensional accuracy over decades, and requires no hard coat. For applications where optical purity and scratch permanence are the primary value proposition, nothing else matches it.

For sport applications, mineral glass is not suitable. It shatters on significant impact, creating sharp fragments — a disqualifying failure mode for any active use. It is also the heaviest sunglass material at 2.53 g/cm³, nearly twice the density of CR-39.

• Best for: Luxury fashion, photography, heritage / collector eyewear, low-activity outdoor use

• Not recommended for: Any sport application, children's eyewear, or any use where lens impact is a realistic scenario

Quick Reference: Substrate Selection by Sport