Front-surface warpage of glasses is common

Invariably, I find some orders that should have been rejected. A number of reasons explain why the jobs were not rejected:

1. The opticians did not check the jobs. When opticians get busy, one of the things they'll do less thoroughly is check incoming jobs. The rationale is that the laboratory has already checked them, so why bother? Having supervised two laboratories in my career, I can tell you that when labs get busy the final inspection process can become a lot less rigorous.

3. The opticians have not been trained properly on how to perform a final inspection. This is often the case. It is surely true for front-surface warpage.