Soft and hard cheeses are made after curd, which is solid, is separated from whey, which is liquid. Cheese baskets or cradles have been used for centuries to drip off whey. These devices were woven of natural materials, usually strips of oak splint. Cheese drainers were colander-like vessels of ceramic and later of punctured sheet metal. Some cheese drainers had a weighted lid that rested on top of the curds. A large cheese press was needed to apply great pressure to make a large, hard cheese. The cheese press resembled a sawhorse to which was attached a round wooden container that had holes in the bottom and a long wooden lever that pushed a presser against the curds in the container. The first U.S. patent for a cheese press was granted in 1812, and many patented and homemade presses followed. Fancy tin egg cheese and cottage cheese strainer molds in heart and other shapes were made in the 1850s to 1870s in Pennsylvania. Long, thin, flexible steel cheese knives and whips have been used since the middle of the nineteenth century to break curds into large or small pieces for soft cheeses. The knives are used in the making of hard cheeses to mix in thickening and curdling agents, such as rennet, as well as salt and coloring and to break up the curds to make the cheese smooth.