Michter's Pot Still Sour Mash Whiskey, which was the company's most popular expression before it declared bankruptcy in 1919, is made in accordance with original sour mash tradition. By using sour mash, which refers to the art of using a small amount of spent mash from an older batch of whiskey in order to catalyze fermentation in a new batch of whiskey, Pratt is able to maintain consistency with each bottling. While Magliocco readily admits that he wanted to pay tribute to the original Michter's Sour Mash, which was comprised of a mash of 50% rye, 38% corn and 12% barley, the current release isn't an attempt to reproduce it exactly. Rather, it was inspired by the older version, but with the intention of improving it. "If it was like everything else," says Magliocco, "we wouldn't have released it."

Michter's US*1 Single Barrel Straight Rye Whiskey is made from a mash comprised primarily of fresh, plump rye grains. Once the grains are harvested, they are sheared so that during fermentation, the grains are saturated with more flavor. After the grains have been fermented, they are distilled through a copper-pot still before being matured in charred, American oak barrels. The barrels are allowed to rest in a heat-cycled warehouse, which forces the wood to expand and contract as the temperature rises and falls. This heat cycling causes the whiskey and wood to mingle with each other, and contributes notes of marmalade and light caramel to the rye. Once Willie Pratt — Michter's Master Distiller — determines that the rye has reached its peak flavor, each bottle is filled and sealed by hand.