As watercolor paints are semi-translucent, papers play a key role in the finished work of art. The paper’s brightness and texture are just as critical as the choice in pigments. Papers most suitable to this water-based medium accept a watercolor wash evenly with reproducible results.
The key ingredient that that makes a high-quality watercolor paper stand out as exceptional is the sizing - the invisible material used in the paper-making process to make the paper more resistant to water. The sizing enables the washing out of color and reworking the same area, which is key for a watercolor papers. Substantial sizing also prevents the fibers from buckling.
There are a variety of surfaces for different watercolor applications, but for the most part watercolor papers are classified as Hot Press (HP) exhibiting a smooth surface, which is prefect for fine detailed images; Cold Press (CP) having a more textured surface; and Rough (R), as the name implies, a highly textured surface.
A new synthetic paper called Yupo has recently caught on as a unique surface for the watercolor technique. Yupo’s ultra smooth non-porous surface allows the artist to erase the brush strokes during the painting process. The paint dries only by oxidization with the use of a hair dryer slowly across the sheet. As with most artistic processes it’s best to experiment to find the paper most suitable to your needs.