As you ease the bell jar back down onto its seat, past the evaporation fixture, it is quite easy to chip a $600 jar. Chipped bell jars are a perennial problem in EM labs. They degrade vacuum in evaporators resulting in lower quality films and ultimately shorten the life of the vacuum system. This note describes a new resin that I have used for repairing bell jar chips.

A common chip can be seen in Fig. 1. It was caused by crashing the bell jar into the evaporation fixture. The chip is less than 0.5mm deep. Beside it you can see another chip that will not be treated as it does not extend to the jar edge.