Old No. 7 (sometimes referred to as Black Label or just Jack) is made from a mash bill of 80% corn, 12% barley, and 8% rye. Limestone-filtered water and a starter mash (aka sour mash) from previous batches are added for fermentation to allow for consistency. After a six-day fermentation, the mash is distilled to 140 proof. The new-make whiskey is then charcoal-mellowed through 10 feet of maple charcoal prior to aging. Aged at least four years in new, charred American oak barrels which the distillery makes itself.