Buffered Museum Mat Board –vs- Un-buffered Museum Mat Board
Most items that require conservation framing are also best protected when they are mounted and matted on boards that additionally contain a reserve of calcium carbonate. This is an alkaline substance that guards against acids encountered in handling, in the environment or in the art itself.
Un-Buffered Museum Mat Board
There are some items, though, that "prefer" a low-alkaline
environment. This prevents degradation due to chemical reactions
between the buffering agent and the materials in the art.
These items consist either partially or entirely of protein-based
fibers such as silk, wool or leather. Other, not-so-obvious,
offenders are older photographs with protein-based emulsions and
casings. These are harder for framers to identify, so
it is best to use a non-buffered board on any photograph that is
suspect.
Click here to order Un-Buffered pure Museum Rag Mat Board in standard frame sizes and custom picture matting.
Some of the types of photographs needing a non-alkaline environment, the years of their popularity, and brief explanations:
- Ambrotype 1847-1880 (glass plate, use non-buffered board if displayed in original leather case)
- Calotype 1841-1856 (salted paper, beeswax finish)
- Carbon Print 1855-present (has heavy coat of animal protein gelatin, in relief, on the surface)
- Chromogenic-type prints 1942-present (very unstable, will show color shifts to orange within 15-20 years)
- Crayon print 1860-1900 (image out of focus, charcoal or crayon lines visible on surface)
- Cyanotype 1895-1920 (irons salts used to create image, no surface binder or coating for protection)
- Daguerreotype 1839-1870 (thin copper sheet, plated with silver, sealed under glass, often displayed in leather)
- Dye Transfer 1946-present (gelatin used in a three-color dye transfer process)
- Gaslight Paper 1881-1960 (gelatin emulsion on paper)
- Gum prints 1858-1920 (hand-manipulated Gun Arabic emulsion to simulate painting, undercoating of gelatin, use non-buffered board if mat will touch emulsion rather than paper border)
- Ilfochrome Classic 1963-present (delicate, super-glossy surface, polyester base)
- Ivorytype 1855-1876 (protein-based albumen emulsion on a faux-ivory base or behind glass: use non-buffered board if photo is not in original mount)
- Oil Pigment 1904-1930 (oil-based inks coated with gelatin, use non-buffered rag if board is touching emulsion)
- Photogravure 1880-1920 (usually mounted between another page and a cover sheet, often an original single print, often quite brittle and delicate)
- Polaroid Black/White 1948-present (thick, sensitive coating, brushed on after processing)
- Silver Gelatin Print 1974-present (most are black and white, or hand colored, has gelatin binder layer)
- Tintype 1854-1930 (coated on brown or black iron plate, often rusted under image, some are hand-tinted and coated with varnish)
- UltraStable Permanent Color 1991-present (modernization of old carbon process, very expensive, matte surface but possibly on any substrate imaginable)
These recommendations and definitions were taken from the following resources:
Framing Photography; Allan R. Lamb
Needlework Framing; Vivian Kistler
Preserving Textiles; H. Mailand and D. Alig
The Framer's Book of materials and Techniques; Paul Frederick
Customer Care Representative for Crescent Cardboard
and Certified Picture Framer; Deanne Row