Mat (picture framing)
In the picture framing industry, a mat (or matte, or mount in British English) is a thin, flat piece of paper-based material included within a picture frame, which serves as additional decoration and to perform several other, more practical functions, such as separating the art from the glass.
The picture-framing mat is most commonly known by laymen for its use as additional decoration to enhance the look of a framed piece, sometimes in conjunction with a fillet or more rarely, liners made of wooden moulding with a cloth surface.
Mats can be decorated as described below, used as a surface for the continuation of the artwork within, or can incorporate three-dimensional aspects, though the last two are highly unusual.
(There have been examples of sandpaper being used to sand into the mat and reveal the core, or incisions made into it with the same result.)
They tend to take well to minor surface additions, including ink and paint (a very wide variety of other media, including fumage, have been used); cloth-covered mats can also have objects such as pins, flags or cloth patches pinned or sewn to them, a technique frequently used in shadowboxing to avoid having to glue items to the backing.
By creating a larger bottom margin and off-setting the mat you draw the eye to physical center of the image.
One of the most important functions is that it separates the glass from the art or document being framed; this is primarily important because any condensation that develops on the inside of the glass can be transferred to the piece if they are not separated, resulting in water damage, mold or mildew.
Additionally, some types of art, such as pastels or chalk pictures, can smudge easily and should be separated from the glass for that reason.
In archival framing, paper items are not typically glued down to the backing, as it prevents anyone in the future from being able to safely and easily remove it to replace damaged frames, backing or mats, and can make restoration of a damaged document or art piece more difficult.
There are several categories of mat board and they are all separated by the level of protection offered the art work or artifact being framed.
The hierarchy of mat board quality is as follows: Caution must be exercised in selecting the type of framing desired.
Art work that is desired to last long term (more than 75 years) can be damaged by improper mat boards that are used intentionally to lower cost.
In addition, correct "conservation" framing includes all components,[10] not just the mat board used directly behind the glass.
Until recently, there were no truly "archival"-quality foamcore boards available, though a number of foamcore brands exist with buffered surfaces and the Nielsen Bainbridge company now produces one[11] that is claimed to both block the intrusion of airborne pollutants and to avoid the problem of outgassing that non-archival foamboards may fall prey to; for this reason, and due to many smaller frames' shallow depths, it is not uncommon to see mat boards used as backing for a picture frame as well, though foamcore and mounting boards tend to be stiffer.
It is also important, if long-term preservation is of concern, to make sure the framer is using good conservation framing technique.
