From the 1300s onward, the middle classes in northern Europe wanted drinking vessels of a finer material than wood or earthenware but sturdier than the thin, more precious glass produced in earlier centuries. As a result, glass workshops produced thicker, more utilitarian vessels of a greenish-blue color. Called Waldglas or forest glass, this glass was made in rural workshops located in forests where there was a plentiful supply of wood fuel for the glass furnaces. Its color was caused by the iron impurities in the sand used as the primary ingredient of the glass.
Forest glass wares were made in distinctive forms to meet their functional requirements. For example, they were frequently decorated with prunts, or blobs of glass, applied to the exterior of the vessel, whose function may have been to allow the drinker to securely grip them, even with the greasy hands that resulted from eating without utensils.
A sixteenth-century Lutheran pastor referred to a beaker of this form as a Krautstrunk,literally "a cabbage stalk."