The process of making tea was laborious and expensive. Freshly picked tea leaves were graded, washed, steamed, pressed, ground, molded into cakes, and roasted. During the Tang dynasty (618–907), the cakes were crushed, ground into powder, and boiled with water. Various other substances were often then added for flavor and aroma. The tea was served ladled into bowls. In the Song dynasty (960–1279), tea was ground into a finer powder, sifted, and placed directly into the tea bowls. After the addition of boiled water, the tea was whipped into a froth with a bamboo whisk.