Watercolor paintings are created using pure pigments mixed with a water-based solution. The history of watercolor dates back to as early as cave paintings found in Europe from the Paleolithic period, and ancient Egyptians used watercolors to illustrate books. Watercolor hit its stride during the Renaissance and was used as a popular medium by many artists from that time, usually to paint botanical pictures depicting flowers and other plant life. The German artist Albrecht Dürer was one of the earliest advocates of the use of watercolors, and he used watercolors to create many botanical, wildlife, and landscape paintings, including House by a Pond. In fact, the company Faber-Castell even manufactures a set of watercolor pencils that are named after him. Traditionally, watercolors are most commonly applied to paper, particularly watercolor paper, which is made either completely or mostly with cotton. Cotton minimizes water distortion when the paper is wet, and results in a nice texture when dried. However, watercolors can also be used on papyrus, bark, plastic, vellum, leather, fabric, wood, and canvas materials.