A stir bar, or spin bar, is a small white oblong Teflon-covered magnet. These bars have only one purpose: to stir solutions. They are used in conjunction with a stir motor. You place the stir bar in a container of liquid, then place the container over a stir motor. When you turn the stir motor on, the bar spins and the liquid is stirred.
Stir bars tend to stick to anything metal in your lab drawer. Thus, they are often hard to find. If yours goes missing, try shaking all of the clamps and spatulas in your drawer to see if it comes loose. Another place many stir bars are lost is in the waste or used acetone containers. Students dump a completed reaction mixture and throw the stir bar out with the waste liquid. Prevent this from happening by using a stir bar retriever. These are Teflon-coated long rods with a magnet at the end; dip them into a solution containing a stir bar and the stir bar will stick to the rod and be lifted out of the container.
Back to Glassware and Equipment