Damage Done by Non-Acid-Free Materials
If you’ve ever removed the frame off of an old black and white photograph and discover discoloration under the frame, this if the result of acidic paper over time. When exposed to the elements, the acid in paper, matting and frame backings can change the chemical composition of the artwork, affecting color and image clarity.

Another form of damage is chemical burning. When wood pulp, which is essentially sulfur, combines with water in the atmosphere, you get sulfurous acid. All non-acid-free paper lets off a microscopic fuming of sulfurous acid, which causes paper to become dry, brittle and brown.

Why Framing Materials Matter

Art and photographs not only need to be produced on acid-free paper, but to truly protect them over time they need to be framed with all acid-free materials. These framing elements can damage artwork if you choose the wrong products:
Mount board
Window mounts (shadow)
Filler board
Backing paper
Wood frames
Adhesive

The commonality of these materials is that they can easily contain wood pulp that hasn’t been properly treated to remove lignin or protect alkalinity.

Testing Existing Framing Materials
Upon inspection, it is easy to check already-framed pictures for framing material acidity. Mount boards are made up of layers of materials. When you look at the layers of the mount (typically visible in the framer cuts of the beveled mount window) you’ll see either slightly yellowish layers that indicated wood-pulp board or pure white layers of rag board. Yellowing backing paper also indicates that at least some of the material used during framing is not acid-free.

Another tell-tale sign is a brownish darkening on the inner edge of the mat window. By the time you notice the darkening on the edges of the picture image, the damage beneath is already severe.

If art was framed using non-acid-free materials, gently remove the art if possible and store it in a cool, dry, dark place until it can be reframed with acid-free framing.

Removing the acidic frame, mount and backing paper will help prevent further damage.
Prevention

To prevent deterioration of your art, ensure the quality of the materials used during framing meet International Organization of Standardization (ISO) standards. The ISO 18902 is the key quality standard with respect to photos and the ability to preserve and protect photos for extended periods. Check the framing or mounting package and product information for the statement “Meets Imaging materials – Processed imaging materials – Albums, framing and storage materials.” This will tell you that the materials meet necessary ISO requirements for proper preservation.

Some materials that do not indicate meeting ISO standards may claim to be “acid-free” or “conservation board.” However, be sure to check with the manufacturer about how they define this, as it may not be up to the standard necessary to properly frame and preserve your art.

Choosing high-quality acid-free materials throughout the framing process will ensure your art is preserved and protected against deterioration. With a variety of properly treated and acid-free options to fit any project need and budget, it’s easy to make a modest investment that will keep your art in top shape for years to come.