Are PTFE stir bars resistant to all lab solvents? It seems like glass-coated stir bars are a specialty item.  Standard stir bars are coated in PTFE.  Is PTFE resistant to all typical lab solvents?  Or is there a reference to check to ensure it is inert to the chemicals being stirred?
This may not be the answer that you are looking for, but I remember a project, for which we had to replace PTFE stirring bars with their glass-coated counterparts.

It is true that PTFE is resistant to most of the solvents used, but it is not really hard and resistant to abrasion.

In a study where aqueous suspensions of metal silicides were stirred, we recognized very soon that the PTFE covers didn't last very long. The stirring bars were polished down to the metal core, which spoiled the experiment. Glass-covered stirring bars turned out to be a viable alternative here.