Given The Conservation Center’s history of treating artworks that have succumbed to fire and flood damage, it may surprise you to know that a few of the most common culprits of damage are poor materials, framing, and storage techniques. Luckily, with proper foresight and preparation, most of this damage is preventable. In this article we will examine some of the common "red flags" to look for in consideration of your own framed art and heirlooms.
Within the dialogue of proper display and framing, archival materials reign supreme. But what does archival really mean? In 1869, the method of mass-producing paper changed dramatically. The pulp source used for making paper materials shifted from cotton or linen to wood pulp. A century later, an American chemist and paper conservator by the name of W.J. Barrow published the first studies that cited acid as a significant cause of paper deterioration. Since then, conservators have been actively avoiding the use of acidic and non-archival materials in display and framing. Note that something that is archival will be acid-free, but something that is acid-free may not always be archival.
What happens when non-archival materials are used? "Acid burn is a type of damage seen in various forms of paper-based substrates in which the acidic content of framing and housing materials comes into contact with a work of art on paper that in some cases may or may not contain trace evidence of acidity itself. What we commonly see in works of art on paper that have been poorly framed in the past is certain trace elements of yellow and brown stains that have migrated into the sheet. This is due to the acidic content within the framing materials coming in direct contact with the work of art," says Brian Kapernekas, Senior Conservator of Works of Art on Paper at The Center.
Brian continues, "What is pH? It is an abbreviation for potential Hydrogen which is the measure of acidity or alkalinity in a substance. The scale of pH levels are measured between 0-14. The rule of thumb is that 7-8 is neutral and good, anything below 7 is acidic, anything above 7 is alkaline. Works of art on paper that consist of 100% cotton rag usually has a neutral pH level around 7-8. When these types of papers are placed in an acidic environment, it may start to take on lower acidic pH levels regardless of its buffered nature and start to discolor. This is mostly due to the acidic content within, say a cardboard backing, that has begun to break down imparting acidity into the work of art. Depending on the type of paper and its housing, the discoloration that develops into the sheet can vary over time."
"In some cases light strike may exacerbate the situation. This is a term used to describe the effects of ultraviolet (UV) rays passing through unprotected non UV filtered glazing causing some inks and pigments to fade and paper to darken in appearance. This essentially assists in breaking down the pH levels in the paper, thus increasing the levels of acid content within the poorly framed housing materials," states Brian.
Glazing is the first line of defense when it comes to blocking out environmental factors such as dirt, dust, and harmful UV rays. The Center deals mainly with two types of archival glazing, which are visually the same. The first, a UV filtering acrylic, has impact resistant qualities and is recommended for pieces frequently loaned or transported, since glass can break, resulting in damage to the artwork such as scratches, tears, abrasions, and gouges. Generally lighter and more stable than glass, acrylic is preferred for housing larger pieces as well.
Glass, on the other hand, is a great choice for pastels or charcoal pieces. Pastels and charcoal have a tendency to shed over time, and the shedding process can be exacerbated by acrylic, which can attract the pastel onto the glazing due to static charge. Paintings are not generally displayed with glazing, but there are some exceptions. Painting techniques have a tendency to be more three dimensional than paper pieces and glazing “can sometimes distract the viewer from the immediate aesthetic nuances of the paint layer,” according to Senior Painting Conservator Amber Schabdach at The Center. Regardless of the type of glazing used, it is important that spacers be installed so that the glass (or acrylic glazing) does not come in contact with the art. Improper distance from the glazing may potentially cause off-gassing or adhesion.
Mat and mount boards are used to act as an “inner frame” for the artwork. Archival boards are made out of treated cotton or linen and are typically available in 4- and 8-ply.
8-ply boards offer greater rigidity and offer increased depth when used as a mat. Generally, presentation options include float, engaged, or stacked mats. Decorative options can include French or gilded mats. When float mounting, extra attention must be paid to spacing the artwork with appropriate distance from the glazing.
While the mat and mount serve an important purpose, hinges are what actually secure the artwork in place. When hinging works on paper, Kozo tissue, a very thin, but strong, Japanese paper should be used whenever possible. The hinge is best applied with reversible adhesives such as wheat starch paste or methylcellulose, both of which are water-based. Non-archival tapes and irreversible adhesives will damage the works, prompting skinning, tears, or staining to the paper support. Other non-invasive options are photo corners or sink mats because they are easily reversed and do not physically alter the artwork. (please refer to the sink mat article in the newsletter for more details)
Backing boards protect the back of the artwork and provide rigidity and support inside the frame. Paintings that are unframed should have a backing board as a precautionary measure to protect the back of the piece from impact as well as dust and debris. A preferred material for backing is Coroplast; which is a corrugated polypropylene board that is rigid, resistant to puncture and moisture. Other appropriate materials include archival 8-ply mat boards and archival corrugated blue boards. Non-archival materials such as foam board, cardboard, and wood are harmful and should be replaced.
As frames are typically made out of wood, they should be sealed so that the natural acidity of the wood does not leech into the framing package. Ideally, the inner rabbets of the frame should be isolated so that the wood is not in direct contact with the art. The artwork should be safely secured within the frame with the appropriate spacing implements and depth so that both the artwork and the frame have the ability to expand and contract from climate fluctuations in the environment.
An archival tape such as Tyvek or J-Lar should be used to seal the framing package within the frame.
The next important element is hanging hardware, a practical and basic element which is often overlooked. "I have fixed many frames that have fallen off the wall because of poor hanging hardware. When was the last time the hardware on your artwork was checked? Has it been years? I have seen stereo wire, clothes hangers, and twine to hang a piece of art, sometimes very substantial paintings. If the hardware and wire are too weak or not properly secured to the frame, it will fail; it’s just a matter of when. This can lead to damage of the frame as well as the work of art. Proper hanging hardware is a simple fix that can prevent damage." says Josh McCauley, Senior Gilding and Frame Conservator at The Center. In addition to the hardware on the piece, the hardware installed on the wall is critical to safe display of your piece. Art handlers can advise on the proper hooks, anchors and mounts as well as aesthetics of the location of the installation.
Artwork should be displayed away from direct sunlight, high traffic areas, as well as locations prone to temperature and humidity changes (fireplaces, bathrooms, and kitchens). Fluctuating environmental conditions can be detrimental and accumulative damage is often the result. General recommendations in the field are 68-72 degrees and 40-50% relative humidity are preferred. Most importantly, consistent levels and low fluctuations should be maintained to minimize the potential for damage.
The Center advises that any piece of art that was framed or put into storage 15 or more years ago, should be re-examined to ensure it is housed with archival materials and UV protective glazing. It takes years of experience to learn the various nuances constantly changing and adapting as research and technology continue to inform our field every year. We all strive to learn more about improving our approaches, methods, materials, and techniques within the vast and ever-changing field of art preservation. Taking the proper precautions will extend the longevity of your art and heirlooms, allowing them to be available for generations to enjoy and appreciate.