The board used must be of good quality as the decomposition products in poor quality boards will eventually migrate to the artwork causing discolouration and embrittlement. There are many good quality matboards on the market but the consumer must be wary of certain jargon that is used. The board must be made from a good quality fibre such as cotton or if it is wood fibre only alpha cellulose pulp is acceptable. The board can be slightly alkaline or have a neutral pH. The latter is recommended for matting photographic materials. A reliable supplier should be able to supply the technical specifications for the board.
Board is generally available in two, four, and eight ply weights.
As the work of art is attached to the backing board, the board needs to be of sufficient thickness to adequately support it. Four-ply is the minimum that should be used to provide adequate support to an average size work of art on paper. Museums generally choose white or cream coloured boards. Coloured boards of acceptable quality are available but the chosen board should be lightfast and not bleed in the case of accidental water damage. The purpose of the window board is to provide a space between the artwork and the glazing material.