Moonshining was a way of life for many in rural areas. Arguably, is still is for some! It took bravery, skill and the ability to repeatedly outwit the authorities to be successful. They also had to end up with a decent product that was relatively safe and somewhat consistent.
Unlike store-bought liquor, there’s no ABV label on homemade moonshine. Even small variables in the distillation process will affect the percentage of alcohol it contains. There were no alcoholometers to test ABV in the woods, so moonshiners had to come up with their own method of testing the potency of their “shine”.
Experienced and skilled moonshiners gauged the alcohol content of their product by performing a shake test. They would fill a glass jar about 1/2 full of the moonshine, then shake it and watch carefully at the resulting bubbles. Moonshine with a high alcohol content has large bubbles that dissipate within seconds, while small bubbles that last for several minutes indicate a lower alcohol content.
The shake test was a quick and easy way to determine whether or not the moonshine was potent. Some Moonshiners were so skilled they could match the accuracy of an alcoholometer point for point. Most however, were satisfied with the rough estimate the shake test would yield.