What is the primary purpose of a salt pan in eyewear adjustment?

• A. To heat frames for molding
• B. To polish frames
• C. To mark frames
• D. To soften frames for adjusting

Answer: (D)

The material of many plastic eyewear frames is thermoplastic, which means it becomes soft and pliable when heated. Using a salt pan exposes the frame to a controlled warm environment through warm saline water, providing even heat that makes the frame malleable without hotspots. This lets you adjust parts like the temples or bridge to fit the wearer better, then let the frame cool to set the new shape.

This method isn’t about polishing, marking, or simply heating for molding in general. It’s specifically about softening the plastic enough to adjust it safely and accurately. For metal frames or other adjustments, different techniques are used, but the salt pan’s job is to soften thermoplastic frames for precise fitting.