The Volstead Act, commonly spoken about as prohibition, specifically allowed individual farmers to make certain wines on the legal fiction that it was a non-intoxicating fruit-juice for home consumption, and many people did so. Grape farmers took the opportunity to expand business and produced liquid and semi-solid grape concentrates called wine bricks or wine blocks. The demand for the wine bricks led California grape growers to increase their land under cultivation by about 700 percent in the first five years of prohibition. They were making bank.
The grape concentrate was sold with a warning: "After dissolving the brick in a gallon of water, do not place the liquid in a jug away in the cupboard for twenty days, because then it would turn into wine." One grape block producer sold nine varieties: Port, Virginia, Dare, Muscatel, Angelica, Tokay, Sauterne, Riesling, Claretand Burgundy. They promoted the making of wine through their “warning”. The Volstead Act also allowed the sale of sacramental wine to priests and rabbis. Imposters took advantage of this and used it as a loophole to buy wine, as well.