My buddy makes a sourdough loaf often, and keeps a culture of sourdough bread yeast in his fridge. He feeds it with just flour and water. I had this idea a while back to do a sourdough stout: 40% Wheat, 20% Maris, 20% Rye, 10% Flaked Barley, 5% Chocolate, 5% Roasted Barley. Now I'm thinking of fermenting it on his yeast culture, and see what happens. My concerns: Can I get it to at least 70% attenuation? Will this yeast create a full blown infection? If so, should I get new equipment for a sour project? I don't want to infect all my equipment with an unsure beer. Is this going to be a slightly funky bready stout? Or this even worth it at all? Thoughts?