and in doing so can create a huge variety of bourbons. Most distillers carefully keep their mash bills a secret. Not the case with Four Roses, a company that uses two different recipes: “OB,” containing 60 percent corn, 35 percent rye, and 5 percent malted barley; and “OE,” with the ratio of the same ingredients at 75 percent, 20 percent, and 5 percent.