Initially, all watercolor papers are made the same way, with the exception of rice paper. Sizing or glue is added to the pulp to hold the paper together. The amount of sizing varies from brand to brand making each paper unique. With some papers, an additional sizing is added after the paper dries. This is surface sizing.
Another factor in choosing papers is the texture. Papers are categorized as hot pressed, which is smooth, cold pressed which is textured, and rough, which is very textured.
Generally if you want to do a very detailed painting, hot pressed is preferrable. When painting on hot pressed paper, the "wash" when applied does not spread and tends to stay on the surface. This enables you to put down a wash in a precise manner. The disadvantage of this kind of surface is that additional layering tends to make the colors less transparent and "muddy".
The cold pressed and rough papers will absorb pigments into the paper more than the hot pressed. When you apply a wash the colors will spread more. These papers allow for more variations of value and color. Because the wash sinks into the paper, you can apply more layers. These papers also emphasize the textures of the subject you are painting.
The surfaced sized papers are more versatile. Because the sizing is water soluble, it can be removed with water. You can create a painting with more detail if you leave the sizing on, or remove it to allow you to paint more freely.
Paper comes in several standard weights: 90 lb, 140 lb, 240 lb and 300 lb. The weight of the paper is determined by the weight of 500 sheets of standard size paper which is 22" x 30". I always use 300 lb paper because it is thicker and will not buckle as much when wet. Also because of its thickness more layers can be applied.
During the painting process I will also want to do some lifting or removing of pigment. Lifting can be done when the paper is still wet, or can be removed after the wash has dried. For this process a paper that has a good amount of internal sizing is best. If the paper does not have enough sizing it can easily tear.
So, considering all the properties of watercolor papers available to me, the paper I chose for this subject is Moulin Du Roy, a cold pressed paper with no surface sizing and medium internal sizing.
I will discuss the drawing shown here, in the next blog.