Framing Terms Glossary - Rag Museum Board, Conservation Framing, Non-archival Mat & Mountboard

Acid free – Acids present in wood pulp products cause discoloration and degradation. Acid free matboards have been chemically treated to neutralize those acids for the short term. Over time these boards will discolor and fade and may also leave an acid burn where the mat touches the art. Acid free does not mean archival. Also called pH neutral.

Alpha Cellulose – A higher quality of wood pulp-based matboard. This product is chemically treated to a high degree to render it totally archival. Should not cause damage to artwork.

Archival w/ Acid Free Foam Core- This is a term used to describe the Bainbridge Foam Core that is referred to as both Acid Free and Archival. The surface papers of this foam board are indeed archival. The foam inside is not archival, although it is not made from wood pulp and therefore is not naturally acidic, it is still not completely archival and so we have labeled it as acid free foam core surrounded by archival papers.

Archival – refers to a product that can be used without harmful effects in the framing, conservation or care of art. It means the product should last indefinitely without degradation. Also called permanent, conservation quality or museum quality.

Bevel cut – the standard 45 degree angle cut of a mat window.

Black core – when the core and the back paper of the matboard is black. The bevel edge at the window therefore shows as a thin black line.

Blank – a mat that is cut without a window.

Buffered - when calcium carbonate is added to a paper product to render it alkaline and therefore more likely to absorb acids and other pollutants in framing products and in the air.

Conservation Board – matboard that meets industry standards for permanence and that can be used for all conservation and museum quality framing and preservation.

Double mat – two mats layered one on top of the other, with a fraction of the bottom mat revealed at the window edge. Double matting provides an opportunity to feature a second mat color and/or to create a more dimensional arena for the artwork.

Fall Out – the piece of matboard that “drops out” when the mat window is cut. Edges are beveled.

Glazing – glass or acrylic (often called plexiglas).

Lignin – a binding substance in wood & wood pulp products. As it breaks down it’s acidic components cause deterioration and discoloring. It is the substance that is removed or neutralized to render a matboard acid free or pH neutral.

Museum Board – matboard that meets industry standards for permanence and that can be used for all conservation framing. Often used to denote board made of cotton.

Non-buffered – matboard that is not treated with calcium carbonate to increase its alkalinity. Research indicates that some types of photographs such as albumen, chromogenic, dye transfer and cyanotypes should be matted and backed with non-buffered, 100% cotton boards.

pH Neutral – when a product like matboard is treated to balance the pH and be therefore more likely to resist natural deterioration. An alternate term for acid-free.

Ply – matboard is manufactured in layers, or plies, that are laminated one on top each other. The standard matboard thickness is 4 ply, but 6 ply and 8 ply boards are also available. 8 ply is twice as thick as 4 ply, 6 ply is 1.5 times as thick as 4 ply.

Rabbet – the inside depth of the frame moulding where your glazing, mat, art, and mountboard sit. R

Radius Cut – when the corners of a rectangular mat window are rounded.

Rag board/rag mat – matboard made from cotton. Cotton is naturally acid and lignin free and requires no chemical treatments to render it archival. Accepted as the top tier of conservation matting and the most environmentally responsible matting option.

Reveal – the amount of bottom mat that is revealed in a double or triple mat. Also known as a setback.

Reverse Bevel – An alternate way of cutting the window of a mat. The 45 degree angle slopes back from the face of the mat so no bevel shows. Useful when matting art created with dusty media like chalk pastels - dust drifts down behind the bevel and is hidden. Also appropriate when a clean, sharp edge with no bevel is aesthetically preferred.

Setback – the amount of bottom mat that is revealed in a double or triple mat. Also known as a reveal

Single Mat -  When the mat only has one layer. A double mat would have another one underneath that you would only see a small amount of. A single mat is just one mat layer with a window cut in it.

Solid core – all 4 ply of the matboard are the same color. Therefore the bevel will be the same color as the front and back surfaces of the board.

Step Cut – a rectangular mat window whose corners are cut with a 90 degree “notch”. The square notch extends into the window opening an average of ½”. These are not available to order over the web and there is a 10.00 set-up fee to do this cut. Please call Customer Service for more information.

Vellum – this term indicates a smooth and texture-free mat surface.

V-Groove – a decorative line cut into the face of mat borders. Line is cut at an angle to form a v shape that reveals approximately 1/16th of an inch of mat core. These are not available to order over the web and there is a 10.00 set-up fee to do this cut. Please call Customer Service for more information.