LABALPHA 6Pcs PTFE Magnetic Stirrer Mixer Stir Bar, Magnetic Stir Bar 10mm/0.39 inch

I have a Corning mixer/stirrer that I bought these for and they work perfectly in them. Only tested on thinner solutions so something that is thicker might be a little trickier with these.

I used these to stir a very visqus liquid while using the hot plate on and they work really well. I got the small sided ones and they work great for small applications.

Other brands I've tried were very unbalanced and would spin off at higher speeds. These are mostly well balanced and spin up to higher speeds effectively.

I use my magnetic stirrer in homebrewing beer. It’s a big and powerful one that I made myself and use to stir up liquids up to 6 gallons (23 liters) in glass carboys and buckets. It’s important that the magnetic stir bars are easy to sanitize to prevent potential infection and PTFE is a good material for this – it’s inert to most sanitizers and can be boiled. I found that the length of the stir bar has a very big effect on performance. Using a long stir bar (e.g. 60mm) to stir a large volume of 20 liters or more was not very effective – it would become unstable and shake off the stirrer. I found that a 40mm stirrer was optimum for almost any volume being stirred.Some of my other stir bars had a raised rib around their center. This meant that the stir bar would have point contact at its center with the bottom of the vessel – which should make it easier to spin and be quieter. These stir bars from LabAlpha did not have this rib and so they would make contact with the bottom of the vessel along their length. See the photo for details – note the slight difference in length despite both being labeled as 40mm. I did some tests to compare the two types and found that both stir bars seem to perform much the same and generated a large vortex in a 2,000mL flask without the stir bars coming loose and flying off the stirrer magnet. I felt that the LabAlpha was perhaps a bit quieter.These stir bars from LabAlpha work well and are available at a good price.

I am a biologist and need a few stirriing rods to so gave these a go. They work great and were substantially cheaper than what we typically get though lab supply companies. Time will tell if they hold up, but there is not much to go wrong with a magnetic stirring bar.