Some moonshine stills have a "doubler" or "thumper" between them and the condenser. When a thumper keg is added to a still, it halves the distilling time and doubles the final proof of the beverage.
A thumper keg is simply a second pot or jar that helps draw off the hot water vapor, which in turn helps vaporize the alcohol for a type of second distillation. Before the invention of the thumper, the first output of the still would be run through the system a second time to increase the alcohol content of the moonshine.
The "second pot" is called a thumper keg because when steam is run through it, it makes a thumping sound. We found one person that described the sound as "POP! POP! Thumpa-thumpa-THUMP! Pop! Pop!"
Not legal advice: Despite state laws making moonshine production legal without a permit, federal law prohibits distilling at home for personal consumption. Federal laws trumps state laws.
Get tips for low-risk drinking at Alcohol.org.
In the news, the increasing popularity of micro-distilleries has many consumers turning to "moonshine" when they imbibe, and they don't have to break the law to do it.
The illicit spirit was traditionally made "by the light of the moon," hence its name, but "legal moonshine" is actually an oxymoron. "Moonshine is a illicitly produced spirit based on no taxation," explains Paul Fulmer, head distiller at South Carolina's Dark Corner Distillery.
While their liquor is taxed, the owners of Dark Corner Distillery say their product is paying homage to their heritage. Read more of the story at KSHB Kansas City.