Edit: This is not a Burton Union, but is a good way to harvest happy, healthy yeast for future brews. Thanks to all the great ideas here. It goes right into my 2L flask. I preboil water and cool it in my flask so the yeast drop right into an oxygen depleted water environment and go to sleep. Then when blowoff is done, I just pour off all but 1 jar of water, swirl the yeast to resuspend, pour into a sterile jar and put back into the fridge. Works like a champ! This is Bell's yeast blowing off the top of a Two Hearted clone.