he materials used to mount and frame artwork covers a wide spectrum of quality. Although many people these days understand the reasons for avoiding acid-based paper products, it is probably not clear to most why this is not sufficient to fully protect vulnerable artwork.
COMMON MATTING/MOUNTING MATERIALS
It is true that the low pH (acid content) of low-quality, acid-processed paper goods is extemely destructive of the pigments and dyes of the paints, inks, and other colorants that artists commonly use. This acid can also degrade and destroy the common fiber-based substrates (like papers and fabrics) that artists work on. And, of course, this acid can even destroy the mattes and other mounting materials themselves that are used to contain and present the artwork. Acid-containing materials like newsprint score a "zero" on the red end of the Archival Materials Index (AMI) and are given a grade of "F." The most commonly available matting and mounting materials are not much better, scoring a "25" and rated as "D". These common materials should NEVER be used in framing and presenting serious art.
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The next step up the archival ladder, which many assume to be "perfect," or at least the best available, is the class of materials described as "acid-free." These materials truly represent a major improvement in the attempt to protect valuable artwork by the elimination (or at least a serious reduction) of the highly corrosive acids contained in most paper products. However, as we shall see, this is only one of many sources of destructive chemicals to which art may be exposed. These materials achieve an AMI of somewhere around "50" and rate a mediocre "C" grade.
MUSEUM-GRADE MATERIALS (100% RAG)
Another step of improvement in archival materials is the class of what some have called "conservation" or "museum" grade materials. Common paper products have at least some wood fiber and contain compounds like lignin that are unstable and break down over time. Some of these breakdown byproducts are themselves destructive of artwork, even though the paper originally contained no acid. The manufacturers of "museum" grade products take this effect seriously and produce their "papers" from cotton fibers only. These products may be described as "cotton rag," "100% rag," or "100% alpha cellulose," meaning that there is no wood fiber in the ingredients. This type of material is known to be stable for centuries and goes a long way toward further protecting artworks.
However, this "museum" grade material, just like the "acid-free" material described earlier, is only passively involved in protecting art. That is, it only protects the art from destructive effects that may be caused by the mounting/presenting materials themselves. They do nothing to actively eliminate or reduce destruction from outside sources. These "museum" grade materials are just beginning to enter the "green" zone of archival quality, scoring about a "75" on the index and rating a pretty decent "B" grade.
Even if the mounting and matting materials are made in such a way that they contribute no destructive effects themselves to the artwork they house, this art is still highly vunerable to the ravages of being exposed to modern atmospheric pollutants. These pollutants are a fact of modern life and they number in the hundreds. Some of these gases can be incredibly destructive to art materials (pigments, dyes, fibers, etc.) and unless the art is hermetically sealed and absolutely isolated from exposure to air (and this is just not practical) it is vulnerable. To fully protect the art, these corrosive gases need to be removed or otherwise neutralized from the immediate environment of the art.
As explained elsewhere in this site, Bainbridge manufactures a line of matting and mounting materials called "Artcare" that is based on a patent-protected technology. This technology relies on the amazing properties of a synthetic mineral called zeolite. This mineral contains trillions of nanoscopic pores, which actively absorb reactive/corrosive gases from the air like a sponge. This sponge-like mineral is incorporated as a base ingredient of these mounting materials. As pollutants diffuse into the interior space of a framed work of art, this zeolite absorbs, traps, and effectively removes them from the atmosphere before they can destructively react with the surface of the art. These "Artcare" materials are truly active, rather than simply passive, archival materials. This is currently "as good as it gets," with these materials scoring a "100" on the Archival Materials Index and receiving a perfect "A" grade.
For more information concerning these amazing materials, and protecting valuable artworks from the ravages of common atmospheric pollutants, check out these links:
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This document was updated on 8/14/2005.