Decoration 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. Although matting usually contains only one opening per layer, it may contain none if a picture is "float-mounted" or "top-mounted" (placed on top of the mat), and mats with two or more exist, more commonly with photography of the family or pictures of individual family members type than other types of artwork. Typically the mat or mats, if matched carefully and properly proportioned, serve to help draw the eye in towards the framed piece, or towards a particular key element of the piece. However, while the mat is usually regarded as something to complement or set off the artwork to best effect, or not to interfere or compete with it (neutral-colored mats are often preferred by high-end art galleries,) there are some examples of the mat being regarded by the artist as a part of the artwork. 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. Mats are fairly adaptable in the visual sense. Since they are typically quite thin (
American-made mats are usually 1/16 of an inch thick, for example), they are able to be cut to "stack" inside of a display, allowing for double, triple or quadruple matting, or even allowing for a fillet in between mats. Mats are available in numerous colors and shades and, less commonly, in preprinted patterns or designs. Mats can easily be found or altered to include further decorative features, such as a cloth covering (most commonly
linen or
silk, though mats with
leather coverings or various other types of cloth covering are also available from some companies) or other decorative coverings or coatings (such as metallic coatings, or textured and patterned coatings that can include
rice paper). Because the mat is thin, but not razor-thin, it can also be carved (traditionally by hand, though computerized mat-cutting systems have also been developed), to feature a design, such as lettering or a simple image; since the carving consists mainly of cutting away a small portion of the top decorative layer of the mat, this means that the carved design will show up as the color of the mat's core. (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.) Most mats are available with a white core, black core, or standard (cream colored) core, but a handful of mats are also available with bright green, red, yellow or blue cores. While most mats are generally rectangular in shape, with a rectangular opening, in addition to fairly common oval, oval-apertured mats designed to go with oval frames, there are also very unusual examples of mats in other shapes. Mats are, with very few exceptions, made of paper-based material. 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. It is also possible to affix a small metal plate to the surface of a mat. Such plates are typically made of
brass, and can also be affixed to the picture frame itself if the frame is made of wood. A common form of decoration on non-cloth coated mats is the
French line or
line, and the
French panel or
panel. These forms of matting may also be called
French mats. A
French line or
line is a
line drawn on the mat, usually in ink or paint and usually drawn to form a complete rectangle or square around the opening in the mat. It is used as additional decoration to help draw the eye in towards the center of the display, and can be done in pencil or any color of ink or paint, including metallic inks. A
French panel or
panel is similar to a French line, with the exception that it is thicker, formed from decorative material ranging from
gold leaf to a design in ink or paint. Typically a painted French panel will be done in
watercolor, which is also sometimes referred to as a
watercolor panel. Similar to a French line, is a v-groove. A v-groove is a thin cut into the mat around the edge of the opening, revealing the core. It is used for much the same purpose as the French line. The most common used matting has an equal margin all the way around. On artwork with the visual center lower than actual center. Bottom weighting, or off-sets are used frequently in matting. The bottom margin are made larger than the side and top margins. When looking at an image, the eyes tend to center higher up than the physical center of the image. By creating a larger bottom margin and off-setting the mat you draw the eye to physical center of the image. "Top center" is a subset of bottom weighting where the top and side margins are equal, which creates a visually pleasing effect. This is particularly true in mats where the borders are not equal, such as an 11x14 with an 8x10 opening.
Protection In
archival or
conservation picture framing, mats have several important functions. 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.
Photos should also be separated from the glass because the surface of photographs is particularly easy to damage, and may even separate from its original paper and stick to the glass if wet; for this reason, any framed photograph of value should be framed in such a way that the glass does not directly contact the photo. Additionally, some types of art, such as
pastels or
chalk pictures, can smudge easily and should be separated from the glass for that reason. Another major function of the mat in
archival framing (where the mats used are made of
acid-free and
lignin-free paper) comes into play during the mounting process. 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. Typically, such items are instead held in place against the backing with
mylar "
photo corners" (tiny triangular pockets into which the corners of the paper are put). The added (though slight) weight of mats can help hold a piece in place while also helping to hide the backing and photo corners. In archival framing, the mats are not glued to the piece or backing, but are "
hinged" to the backing with tape, though if more than one mat is used, the mats are typically glued to each other. ==Acidic vs. "acid-free"==