The best art paper is 100 percent rag paper. Rag paper is more durable than wood pulp; it is thicker, absorbs ink better and fades less. Rag paper is made from vegetable fibers, like cotton, linen, ramie and hemp. Paper can contain different percentages of fiber. The more fiber in the paper, the more durable the paper is.
When wood pulp paper is made with an alkaline process and is lignin and sulfur free, it is considered acid-free paper. It does not break down as easily as paper made without this process. Untreated paper turns yellow.
Good quality acid-free paper and 100 percent rag paper have a neutral pH. They are both acid-free papers with equal durability.
A quality coating on wood pulp paper can make it comparable to rag paper in how it handles ink.
Rag paper is preferred because it is thicker even though it is more expensive. Handmade rag paper is valued because it is decorative and colorful.