... two of the other major players producing vodka in the U.S. are Archer-Daniels-Midland and Grain Processing Corp. of Muscatine, Iowa. ADM sells its 190-proof beverage alcohol (product code 020001) packaged one of three ways: "Bulk Truck, Bulk Rail, Tank." Cut it with water -- preferably from a source that will lend itself to a pretty picture on the label -- bottle it, and you're in the vodka business.
Over at Grain Processing Corp., the "focus in producing ethyl alcohol is directed to the distilled spirits and beverage industries." But its Web site brags that "this same high-quality grain neutral spirit is used to produce a variety of 190 proof and benzene-free anhydrous industrial ethyl alcohol products." That is, industrial solvents, mouthwash, hair spray, astringents and such.
...it is largely water that defines what little discernible difference there is between vodkas. If the vodka has been made correctly, it is free from "congeners" -- chemical compounds such as phenols and esters that give spirits flavors and aromas (for better or worse). Pot-still production is likely to leave a few traces of the dreaded congeners, but they are then stripped away by filtering. When the spirit finally comes off the still, it is 95% pure ethanol and 5% distilled water. But you couldn't possibly drink anything at 190 proof, and so the spirit gets cut with H2O. In other words, an 80 proof vodka is 60% water.