In learning how to operate our new beer still I have found yet another reason you have to make sour mash whiskey. And this could be yet another reason it was started and is still in use today. Sweet mash does not like a beer still. Foams up too bad on the trays, I ran a sweet mash yesterday starting up on a product so I had no backset for it. Never will I do that again, it ran but gace me fits the entire time. In all of the old tech books I have read, and in talking to some retired distillers, they say especially on rye you want plenty of backset. Will keep it from foaming and what I term bucking in the still. But I never knew just how true it was till yesterday. Intersting note I learned recently, MGP or the old Seagrams plant always alternates or used to rye mash with a bourbon mash. This lets the backset from the bourbon mash be used in the rye mash, the corn oils reduce foaming better than rye. And no doubt the bourbon backset adds flavor to the rye and the rye backset adds flavor to the bourbon. Whiskey making is an amazing process, learn something everyday. Jim Rutledge always says, remember you are still learning. He is right.