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Optical Materials

CR-39 monomer


There is only one CR-39 monomer, and it only comes from PPG.

For more than six decades, lens wearers have relied on our value lens material, PPG CR-39® monomer, for outstanding optical quality and durability at a low price. Because of our long history,  we have in-depth knowledge of the functional properties and are a leader in the development and production of optical monomers and coatings.


Our proprietary CR-39 allyl diglycol carbonate monomer combines the optics of glass with the durability of a thermoset material. The benefits are clear. Lenses made from CR-39 monomer:

  • stand up to scratches, heat and household chemicals,
  • have less chromatic aberration than polycarbonate lenses,
  • are lightweight and less prone to shattering than glass.
Optical Property Value
Refractive Index 1.498
Abbe Value 59.3
Density 1.31 g/cm3

Licensed Lens Caster Program

The CR-39 Licensed Lens Caster Program identifies those lens casters who are dedicated to preserving the integrity of CR-39 monomer. The program also promotes these licensed lens casters as preferred sources for lenses made from the material.  The program's objective is to provide assurance to labs and retailers that they are getting the product they trust when they specify lenses made with CR-39 monomer.

Participants in the CR-39 Licensed Lens Caster Program must

  • adhere to usage guidelines of the CR-39 monomer trademark,
  • and provide only lenses made with CR-39 monomer to customers who specify or request the resin by name.


Manufactured exclusively by PPG, the patented CR-39 monomer revolutionized the optical industry as the first plastic lens material when it was introduced in 1945 and inspired a great deal of creativity and ingenuity, which led to many of the great plastic lens products available today.

To learn more about the history of CR-39 monomer and the development of ophthalmic lens industry, read "The Stories Behind the Development of Plastic Lenses" by Joseph Bruneni.