Beer Forum

Can I drop a stir bar in my flask prior to boiling when i make starters?
I used to keep them soaking in isopropyl, but it seems like it would be easier to just drop one in and let it boil away to kill of any potential contagions. What kind of plastic are those things made of?

Thanks!

The problem isn't the plastic, but the magnet itself. Heat will degrade and eventually destroy the magnetism in the stirbar. Just soak the thing in a little Star San while the flask boils and cools and carefully drop it in.

Wayne

Seriously? Heat degrades them?

I've boiled them in the lab for years, no problem.

I've been boiling mine for quite awhile with no ill effects. Bug has me worried now, though.

i've boiled mine countless times. i can see how heat would degrade the magnetism but i think it's a sloooooooooow process. you'll probably lose the dang thing before you notice any degradation.

Yes, heat definitely degrades magnets, but the temperature and duration needed to do so depends on the alloy used to make the magnet. The temperature needed is called the Curie Point... maybe the manufacturers of your stir bars have the tech specs available to include what the Curie Point of their magnets are?

Most of the commercial stir bars are teflon coated - boiling is not going to hurt the coating.

I autoclave mine on a weekly basis at work without issues. If you're worried about the magnetic properties dying out, buy a new one when it stops spinning (this would probably be at least a few years). They don't exactly cost much.

Good luck!