I have read a lot about bucket fermenters and if they are scratched on the inside, they need to be replaced.
I am looking at my stir bar and it is not smooth at all. How do you sanitize your stir bar?
If you are going to boil it be sure to put it in the flask before you start heating it up.
I made the mistake once. I started boiling the starter and saw my stir bar sitting there after the boil started. I thought, just drop it in.....bad idea. massive explosive, boil over..
My stir bar had an episode with the garbage disposal and now it's scratched all over. I throw it into the water as I'm heating, leave it in through the 10 minute boil, cool, and dump with the wort. Hope that's good enough.