Acid-free paper: Paper that has varying degrees of cotton fiber base. As an artist when purchasing and or using various papers, it’s important to know what the end result will be that you’re trying to achieve. If you’re doing a quick sketch any paper will (or may) work. If the end result is to create long-lasting art that has professional results in mind, it’s highly recommended that you use 100% cotton rag paper when creating art.

The most paper found in everyday use is made from wood pulp in acid baths. When you look at an old newspaper or magazine the reason why the paper is brown or yellowed is because of the acid content used in making the paper.

In picture framing, there are two major suppliers Crescent and Bainbridge. Depending on your geographic location there may be custom rag mat suppliers. Both companies carry two lines of mats.

1. A standard line that is not 100% acid this line has a thin layer of acid-free paper mounted on the back side of the art to help from acid bleed and is just fine for something that does not fall into the fine art or collectible category.

2. The second and most desirable mats are 100% cotton rag mat boards and come in the three most used colors, white, antique white, and crème colors.

However, since the late 1980s a full line of colors have been introduced. Another technic I’ve used and still use from time to time is to strip a 4ply rag to the back of the mat so whatever touches the art is acid-free. This technique is pretty much mandatory when using fabric-stretched mats.