Watercolor paper

Watercolor paper is paper or substrate onto which an artist applies watercolor paints, pigments or dyes. There are currently many types of paper available that are manufactured for the use with watercolors. Watercolor paper can be made of wood pulp exclusively, or mixed with cotton fibers. Pure cotton watercolor paper is also used by artists though it typically costs more than paper. It is also available as an acid-free medium to help its preservation. Watercolor paper can be described according to the manufacturing process. It can be hot pressed, cold pressed or rough. A number of companies sell watercolor papers, some of them with a long history of production. Paper traditionally comes in either 90, 140 or 300 lb. weights. 
Papyrus was used as a 'paper' onto which the Egyptians applied their water-based paints or pigments.
Arches began production of watercolor paper around 1620. It provided most of the paper used in France during the 1700s. In addition to watercolor paper, Arches also produced paper that was used in documents and paper that was used as currency during the revolution in France. Arches joined other paper manufacturers in the 1950s to form Arjomari Prioux. 
Woven paper was used in print publication in the late 1760s because it was found to be smoother. The watercolor paper at this time was used by artists because it allowed the application of paint without the unevenness of molded paper. James Whatman created a paper specifically for use with water colors by the 1780s. He used gelatin as a sizing that created a protective coating that reduced damage to the paper by repeated wetting, drying and reworking.