Fermcap is great for this. Reduces the risk of the dreaded "Starter Volcano."
I have a nice big cast iron pan. Would it help to prevent scorching if I put the pan on the burner and then the flask in/on the pan?
Where did time go?
I lost a 2L flask to my electric stove . . . had added the extract, was boiling, heard a crack, wort all over my stove. Now I make starters in a pot and just transfer them once they've cooled.