When using pliers to help tighten a loose temple, how should the jaws be positioned when open?

When tightening a loose temple using pliers, the correct positioning of the jaws when open is parallel. This alignment allows for an even grip on the temple without causing excessive pressure on any single point, which could lead to deformity or damage. By maintaining a parallel position, the pliers can effectively distribute force evenly across the length of the temple, ensuring a secure and uniform tightening process.

If the jaws were positioned in ways other than parallel, such as being perpendicular, this would not provide the necessary stability or grip needed to effectively tighten the temple. Similarly, if the jaws were of unequal lengths or rounded, they would not offer the precision and control required for making adjustments without risking damage to the frame. Thus, using parallel jaws is key to properly handling and servicing the temple while maintaining the integrity of the eyewear.