I just bought a 2L erlenmeyer flask from the LHBS. I don’t know the brand, but the supplier to the LHBS is J.D. Carlson. Anyway, I was under the impression that these flasks had flat bottoms. This new one of mine is concave on the inside-bottom, or domed inside. Is this the typical bottom shape for an erlenmeyer, i.e., concave?
I would think it could be a problem. My flask is flat and no issues. I also use a 1gal glass jug for larger starters which has a hump, but it’s more like a plateau. So the bar sits on top of the plateau and spins, but even then, it can be tricky to get it going without throwing the bar.
Sounds iffy but the only way to know will be to test it out. Do it with some water first to make sure and if it tosses it try to bring it back and see if they have anything different. It’s no use if it doesn’t work.
Thanks, but my main question is whether erlenmeyer flasks, in general, have this concave bottom. If so, I’ll have to make it work. If not, then I’ll return it and look for a flat bottomed flask. What shape is yours?
Bought mine at a lab supply and it’s flat.
Mine’s flat and I got it from our host’s store. Stir bar sits in it nicely and will spin really at any point on the bottom if you don’t have it centered right.
They are usually flat bottom.
They’re usually flat and there’s no way you’ll spin a bar in that flask. I’d exchange if possible
Thanks. I’m returning the flask.
All of mine have flat bottoms.
I like a round bottom, butt I prefer my flasks to be flat. 
I haven’t had any luck with anything but flat.
