Watercolor paper is by far the most technically difficult paper to make which may be why no two brands of watercolor paper act the same. But that does not mean to say that one type is better then another, what is “good” for one for one artist may be “bad” another. It all depends on a person’s technique and imagery. I would encourage everyone to try more than one manufacturers brand to see what the different qualities are.
There are 3 terms for gelatine sizing that all mean exactly the same thing:
1. Tub Sizing– because handmade paper is actually soaked in a tub of dilute gelatine and water,
2. Gelatine Sizing– because it is made of gelatine,
3. Surface Sizing–because it is applied to the surface of the paper.
Some manufacturers, like machine made Arches and handmade Twinrocker, surface size their paper with gelatine. Other manufacturers surface size with vegetable starch. All surface sizing helps to keep the paint from sinking into the fibers and becoming “muddy”. However, there are many technical factors that contribute to the way a watercolor paper performs.
What is sizing?
Gelatine sizing is a surface sizing of animal glue or gelatine. In Europe before paper was made, monks wrote on animal hides called parchment and vellum with quill pens. When paper began to be made in Europe in 1150 AD, people wanted the paper to act like parchment and not bleed with water base inks so they dipped the sheets in liquid parchment or hide glue. Today, along with surface sizings like gelatine and starch, papermakers also use modern internal sizing’s that can be added to the pulp itself. Most watercolor paper is both internally and externally sized.
What does sizing do?
Sizing effects the performance of the paper and how it takes the paint, it helps to resist scratching and lets the artist make the necessary changes and corrections when painting. Such as having the ability to lift and remove color. Without it, water and color would soak right in, making it an extremely difficult surface it would react more like a blotting paper or paper towel.