The truth about anti-yellowing polymers.
Most clear iPhone cases turn yellow within 90 days. Here is the chemistry behind it, and how we built a polymer that holds clarity for ten years.
Why clear cases yellow
Polyurethane and TPU plastics oxidize when exposed to UV, body oils and heat. The molecular bonds in standard formulas break down, creating chromophores — the molecules that look yellow to the eye.
The VCASE polymer formula
Our polymer is a custom blend of optical-grade polycarbonate cores with a hardened TPU outer shell. We add UV inhibitors and antioxidants that shield the bonds before they oxidize. The result is clarity that holds for years.
How we test it
Every batch is accelerated-aged in our UV chamber for the equivalent of three years. We measure yellowing with a spectrophotometer and reject anything outside our 0.4 delta-b threshold.