Watercolor is art on paper or another substrate over which an artist uses different colors, pigments, or liquids to create a painting. There are various kinds of paper used for this purpose today, which are manufactured specifically for this purpose. Most commonly, watercolor paper is made from cotton fibers or wood pulp only. However, some paper may also be manufactured from synthetic fibers or even paper, and it is an entirely different type of paper.
Unlike traditional paper, which has natural absorbent properties, watercolor paper has no pores or lines that penetrate liquids. In fact, it may as well not have any absorbent properties at all. This makes it a particularly unique medium in the world of art because the ability of the paper to soak up a large amount of any liquid that falls upon it attracts the attention of the viewer almost immediately, without the process of having to simmer the paper by using other media. In fact, the absorption of any liquid that may fall onto the paper immediately allows it to be painted on directly.
For this reason, the paper requires a special surface prepared by coating it with a gelatin sizing agent to prevent solvents from penetrating the surface. The gelatin sizing serves to protect the artboard from any direct contact with the artist's work and prevents blistering or warping of the board when a sheet of waterfalls on it. Once prepared, the paper is normally ready for its first attempt at a watercolor painting.
Watercolor sheets are generally prepared from a cotton blend in weights of six to twelve ounces, which may vary. (Many manufacturers use a blend of cotton and polyester). The six to twelve ounces of waterskin are placed in a rack designed to house dry materials and then laid out flat to dry over the course of one day. Since most artists prefer a rough, dry surface, this method is often chosen for preparing the watercolor paper.
Because waterskin provides a rough surface, sheets of watercolor paper are prepared from a special type of cotton known as muslin. Because muslin is soft, it absorbs very little water, allowing for consistent application over a long period of time. Muslin can also be used as a cushion underneath an oil painting, allowing the painter to more easily see the depth of the image. Because cotton is porous, watercolors made from cotton will fade over time, especially if exposed to light. This is why many painters prefer using muslin-based watercolor papers.
The process of preparing the watercolor paper begins with the application of a neutralizer. This serves to eliminate any organic compounds the cotton contains, such as lanolin or wool dyes. Any water-based dyes may be mixed with a small amount of alcohol for further reduction in absorption. Then, the papers are washed with a solution of lemon juice and water. The final step is the thorough drying of the material.
Although this paper is considered flat by most artists, the actual flatness of the paper comes from its surface texture. Like any watercolor painting, each brushstroke creates a unique surface texture. Water texture allows the brush to create a different texture within the piece, not just a flat brushstroke. This allows the painter to create a variety of effects, such as shimmering, specular highlights, or a blurry effect.
Two types of watercolor paper are available. They are both pressed, but the pressed paper has a slightly different preparation process than the uncarved variety. Pressed watercolor paper has been pre-cut into sheets that have been formed into a specific shape. The process of pressing involves applying the pigment, or coloring, to the edges of the sheets and taping them together. The taping method provides the pigment with a consistent amount of exposure to the drawing surface.