The acidity of a matboard determines how long it will last and be impacted by sunglight and other atmospheric conditions. We split up acidity into two categories,
acid free and not acid free. True, 100% acid free is only available in cotton-fibre based matboards, these are used for museum art that needs to preserved
for hundreds of years.
Paper mat that is made of wood-pulp is often called acid free as the acid is buffered out through a chemical process.
These are the Conservation
brand of matboards that are sold by most high-end
frame shops. The more common paper mat, often called Decorative
is not acid free but wll still last many years depending on exposure to sunlight and the quality of the glazing. You’ll find these in retail locations.
It’s also important to note that acidity is a factor in both the core of the matboard and the surface. The core is what the matboard is composed of (paper
is then adhered to the core to give the matboard color and texture), White and black cores have acid free cores,
but not necessarily acid free surfaces which means that the core will retain its color, but the acidic surface will still fade and potentially
damage the art work over time. Cream/standard cores are not acid free in either the surface or the core.
Acidity has two main problems:
- Discoloration: the mat will fade or discolor over the years, especially when exposed to lots of light. This typically takes a few decades.
- Damages Art: the art work that is exposed to the acidic paper will brown and discolor over the years. This typically takes a few decades.
Conservation Select mats are what is commonly called acid free, Berkshire and Decorative mats do not have acid free surfaces.