Glass rod

A glass rod

This is used for stirring with. It often has a rubber or plastic top called a policeman. The policeman is used to transfer wet solids.

Remember the general rules of cross contamination. Students often stir with a glass rod, place it flat on the bench and then stir again. This will contaminate the bench surface with liquid, and may transfer impurities from the bench surface back into the liquid. Either leave the glass rod in place, in a clean test tube, or if only a small length is wet it can be balanced over the sink.

Contamination of bench surface by a used glass rod

Usually you will be stirring the contents of a beaker, and beakers are usually fairly tough. Indeed, in crystallization we often deliberately scrape the surface of the beaker with a glass rod in order to encourage crystal formation. However, if you are stirring in a test tube or boiling tube take great care. It is quite easy to put a hole in the bottom of the tube with the glass rod. Similarly, don't attempt to stir the contents of a filter paper - you will put a hole in it! Students have often told me in the past that these holes have magically appeared - the glass rod really did have something to do with it!