I'm interested in that as well, haven't figured out what causes the ashtray aroma in some beers. With cold brewed dark grains I haven't had this, but havent tried beers with lodo method. But I did make split batches of schwarzbier this weekend, with 5% Carafa S3. Dough-in at 35C into water with 0.5g/l sugar and bread yeast, and added hot water with 33mg/l total, no sparge.
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