Why Acetate Frames and PC Lenses Don't Mix ?

Pairing polycarbonate (PC) lenses with acetate frames is a recipe for lens cracking — and the reason comes down to both chemistry and physics.

Acetate is mildly acidic, which gradually degrades PC material over time. Meanwhile, PC lenses carry high internal stress from their injection-molding process. When forced into acetate's tight, shrinking frame groove, the accumulated stress exceeds the lens's tolerance, causing cracks.

The ideal match? Resin lenses (especially MR-8) for acetate frames, and PC lenses for flexible TR90 or metal frames