What lightweight material can be used for injection molded glasses and requires less heat for adjustments?

Cellulose propionate is a lightweight thermoplastic material often used for injection molded glasses. One of its key advantages is that it has a low melting point, which allows for easier and less heat-intensive adjustments during the fitting process. This characteristic makes cellulose propionate a practical choice for eyewear, as it can be shaped and adjusted without the need for high temperatures that could potentially damage the material.

In comparison, cellulose acetate is another material commonly used in eyewear, but it requires higher temperatures for molding and adjustments. Optyl, while also lightweight and thermally stable, can retain its shape better with heat and may not be as easily adjustable as cellulose propionate. PVC, while versatile, is generally heavier and less commonly used in high-quality eyewear due to its rigidity and comfort issues.