Watercolors are a water-base paint made with artist-grade pigments used by watercolor artists. Also often used for color studies for larger works in other mediums, watercolors offer a sense of immediacy. Colors are usually applied using brushes, but many other tools can also used. The most common techniques for applying watercolor are called wet-on-dry and wet-on-wet, along with the dry brush techniques dry-on-dry and dry-on-wet. Colors can be removed while still wet, to various degrees by blotting. Watercolor painting is generally done on paper, but other absorbent grounds can also be used. The papers most preferred by watercolorists are white, rather thick, with high rag content. The surface of cold-pressed watercolor paper is preferred over the overly smooth surface of hot-pressed papers.