There are two different matting configurations when framing a work of art. One method is to have a 'top mat'
with a window and a backing board. When assembled, the art is attached to the backing board and is viewed
through the 'window.' In addition to the aesthetics, the window functions as a spacer to keep the glazing
away from the art. Often, the top mat is omitted. The art is attached to the backer, usually with a 'float'
space allowed on all four sides. In this case, a spacer must be provided to prevent contact of the art to the glazing.
The quality of the mat board is of paramount importance. It must be chemically inert, pH neutral and chemically stable. At Absolute, we use only mat boards that are 100% rag and meet these criteria. A board we often use is Rising Museum Board.
There are many references that provide great detail and devote many pages to a discussion of matting. Rather than re-invent the wheel, if you are interested in greater detail, please visit one of these links: