June 25, 2008 3:58 AM PDT
Next up: taking a starter mash that comes from a previous batch, a step that allows the bourbon to be classified as a sour mash whiskey, and then filling the tub two-thirds with sweet mash that comes from the mash tubs. Next, distillers add 150 gallons of yeast made at Maker's Mark every day from a five-generation-old family strand and then add one more layer of sweet mash. The mixture then ferments for four days. This processes the sugars, producing the alcohol.
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Photo by Daniel Terdiman/CNET News.com
