Stir Bar Size Question

[DCPiet]

Hey guys,

I just got my first stir plate, a used VWR Model 200 Mini-Stirrer, and am wondering what size stir bar to pick up for it. I'll be using a 2L flask, by the way.

I've attached a pic of the rotating magnet with a ruler for scale, it looks to be just under 2.25 inches from end to end. If for some reason the photo below doesn't show up, I've put it up on Twitpic.

Austin Homebrew Supply has 2", as well as a 1", 1 3/16" & 1 3/8" stir bars, and as a first time user I'm a bit confused. I'd appreciate any advice you guys have.

Many thanks!

 

[Catt22]

Looks like a 2" bar would be ideal as it would match the center to center distance between the magnet poles. Anything smaller would likely gravitate to one pole or the other and get thrown.

 

[nediver]

Any of them will work. I like ones that are completely smooth.

2" would be my pref here or 1 1/2"

 

[Catt22]

Any of them will work. I like ones that are completely smooth.

2" would be my pref here or 1 1/2"

I'm not so sure that the smaller ones would work very well at all, particularly the 1" bar. IMO, the stir bars with the center pivot ring are the best choice.

 

[DCPiet]

thanks for the quick replies gents. i was leaning toward the 2" one, figuring the magnets would line us best with that size -- so it's good to hear some confirmation of my speculation...