There are two types of conservation quality mat board—rag and alphacellulose, and both types meet conservation standards. The only type of naturally acid-free mat board is rag mat board that is made from cotton. One benefit of rag board is that it is natural, environmentally friendly, and easily renewable. Standard rag mat board is made with a 100% cotton core and backing, and an acid-free, bleed-resistant colored facing paper. It is more expensive than plain decorative mats, but there are several color and texture options to choose from, such as suede. Standard rag board is recommended when framing fine art prints, valuable documents and photos. When framing important historical, valuable, rare or antique artwork or documents, many conservators choose 100% rag board in which the face, core, and backing are all made of cotton and are one color.