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?
Answer
Labware manufacturers will often put out chemical compatibility charts for their products. A search on Google for the phrase ptfe chemical resistance yields a large number of hits, of varying thoroughness.
One fairly comprehensive one is this one from ThermoFisher Scientific.
Scanning it, PTFE has "Excellent" resistance listed for most solvents, except for pure 3-phenyl-2-propenal, which is "merely" "Good" ("Little or no damage after 30 days of constant exposure.") Lists from other sources have a different sets of compounds, some of which caution against conditions like "dry fluorine" or some rarer compounds. This one lists fluorine, gold monocyanide, and diethylamine as not recommended. (Though a number of other sources - including ThermoFisher - say diethylamine is perfectly fine.)
So PTFE is resistant to pretty much all lab solvents which a major manufacturer of lab equipment thinks it's relevant to mention - but if you have something that you think may be atypical or which you have particular concerns about, do a search for that particular compound or contact the manufacturer for their recommendations.
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