Glossary
mat - A sandwich of two pieces of paper board hinged together. The bottom piece supports the print and the top piece contains an opening, or window, through which the print may be seen.
matboard - A type of paperboard made especially for matting pictures. It is available in a wide variety of colors. The standard size is 30'' or 32'' x 40'', but there is 40 x 60'' also in some colors, and whites are available in several other sizes.
medium format - Usually describes format using 120/220 size film, a common professional format that produces a negative larger than 35mm. 6 x 7 cm and 2-1/4'' square are common image formats. Camera designs vary diversely within this format ranging from SLR, twin lens reflex, and other designs. Films from the first half of the 20th century came in sizes larger than 35mm but vary from the modern medium format dimensions.
methyl cellulose - Any of various gummy products that swell in water and are used as adhesives, emulsifiers and thickeners.
microfiche - A sheet of microfilm containing multiple micro-images in a grid pattern. The most common size produced today is the 105 mm x 148 mm, and the format 60 or 90 pages of information per fiche.
microfilm - (1) A transparent flexible film used for the photographic reproduction of documents in reduced size. (2) Photographic reproductions on this film that can be viewed with a reading device or enlarged to make readable prints.
mil - Unit of thickness equalling one thousandth of an inch (.001''). See also point.
moisture content - The percent of moisture found in finished paper. The amount varies according to atmospheric conditions because paper is hygroscopic.
mounted - Printed matter, photographs or artwork, adhered to or lightly attached to paper or matboard using corners, hinges or dry mounting techniques.
mounting - The attaching of a piece of artwork to a support for the purpose of extending its life or bracing it to be framed. Methods of attaching include corners, hinges and dry mounting.
museum board - 100% cotton matboard. It has a uniform color throughout and is acid- and lignin-free. It is sometimes lumped together with conservator's matboard, which is not 100% cotton but also is acid- and lignin-free.
Mylar & Melinex - DuPont trade names for clear, flexible polyester plastic sheets used to cover prints and documents. Mylar Type D / Melinex 516 has been extensively tested and is approved for photographic and conservation use.
