CR-39 and polycarbonate are established plastic lens materials, but they serve different product priorities. CR-39 is widely used for clear and tinted optical programs and is valued for straightforward processing and tinting. Polycarbonate has a higher refractive index and strong impact performance, making it common where reduced thickness and impact resistance are important. The correct choice depends on the destination market, frame, prescription, testing, and product position.
Key takeaways
- CR-39 is commonly positioned as a standard-index material with broad clear and tint options.
- Polycarbonate is approximately 1.59 index and is selected for its combination of impact performance and thinner-lens potential.
- Material names do not replace destination-market impact and labeling requirements.
- Tinting, coating, surfacing, and frame compatibility must be qualified for the exact material.
Material priorities are different
CR-39 is a thermoset optical resin commonly associated with an index near 1.50. It is used for prescription and plano programs and can be tintable through a dye-bath process, depending on the lens and coating route.
Polycarbonate is a thermoplastic material with an index near 1.59. Its impact behavior makes it common in sports, children's, safety-oriented, and other applications where the applicable product and regulatory requirements are met. It should not be marketed as protective eyewear merely from the material name.
Buyer comparison
Build the material decision around the finished product rather than one isolated property.
| Item | CR-39 | Polycarbonate |
|---|---|---|
| Refractive index | Approximately 1.50 | Approximately 1.59 |
| Typical program | Standard clear, prescription, and tinted ranges | Impact-oriented and thinner-profile ranges |
| Tint route | Often suitable for dye-bath tinting | Frequently colored through material or qualified process |
| Processing control | Confirm hard coat and coating compatibility | Confirm surfacing, coating adhesion, stress, and frame route |
| Compliance question | Required optical and impact criteria | Required optical and impact criteria; material name alone is not proof |
Impact claims need controlled evidence
Impact requirements depend on the destination market and intended product. In the United States, spectacle lenses are subject to impact-resistance provisions under 21 CFR 801.410, with defined testing and exemptions. Other markets may use different standards or documentation.
Ask the supplier to identify the exact test method, sampling plan, report, and product configuration. A report for a plano uncoated sample may not represent every prescription, coating, thickness, or finished eyewear application.
Quotation checklist
Request enough information to keep material, design, treatment, and compliance from being mixed together.
- Material trade name and refractive index
- Finished or semi-finished supply format
- Sphere, cylinder, diameter, and thickness matrix
- Spherical or aspheric design
- Clear, tinted, polarized, photochromic, or blue-filter route
- Hard coat and anti-reflective coating
- Impact test method and destination-market documentation
- Frame compatibility, packaging, and labeling
Buyer questions
Frequently asked questions
Is polycarbonate always thinner than CR-39?
It has higher-index thickness potential, but final thickness also depends on prescription, diameter, design, frame geometry, and minimum-thickness settings.
Can both materials be tinted?
Tint options exist for both, but the production route and achievable colors differ. Approve the exact material, coating, and color sample.
Does polycarbonate automatically make finished eyewear safety certified?
No. Material selection is only one part of a compliant product. The applicable eyewear, lens, testing, marking, and documentation requirements must be met.
Further reading
These external references provide background context. Product availability and performance claims must still be confirmed for the exact item being purchased.