Production of Zhenjiang vinegar begins when a vinegar peimixture is poured into an urn until the urn is half-full. The mixture is kept warm for up to 3 days in summer and 6 days in winter. At that point, rice hull is added and mixed in once per day until the urn is full. Salt is added and the urn is stored for up to 3 months during which it undergoes an aging process. The vinegar is then leached and the soaking liquid from water-soaked, parched rice is added as a color and flavor enhancer.