One of the most commonly seen items in a museum is a painting from a famous artist. These pictures are many centuries old, and have undergone special conservation techniques designed to preserve the masterpiece for posterity. Framing using the proper materials is needed in order to provide protection from such destructive forces as light rays from the sun and air pollution. These are of a special quality called archival by experts in this area, and are essential because they are in contact with the picture. It is important that this type is used here, as the non-archival type is less expensive and may cause serious damage to a painting.
There is also the consideration of museum boards that have to be treated before a painting can have any contact with them. They are sprayed with a chemical to remove any acid material. This will help to guarantee that there is no acid to leach onto the picture, creating a permanent stain. If there is any acidic material in the picture itself, it will actually be absorbed by the museum rags. The most common type of mats being used by museums are the alpha cellulose type, and they are readily available for exhibit quality pictures.
A backboard is also another protection layer designed for matted artwork. It essentially provides security against air which contains a high level of humidity.
Another aspect of conservation framing is the use of Brainbridge boards to guard against ultraviolet rays. There is plenty of documentation showing how UV light can permanently alter the color of a painting. This type of light is very common, emanating from the sun and fluorescent bulbs. These are 2 common sources of light, and will easily penetrate the pigments in the painting, causing a permanent alteration of the shades.
There are a number of protection types available, so Brainbridge boards come in a variety of quality levels to meet the necessary requirements. For oil paintings and photographs especially, alpharag boards are the best choice. There are no wood or lignin components to this type of mat. Thus, they are the perfect choice for producing a frame that is acid free. Since museums are in the business of showcasing works of art, the mat boards also have to blend in and help the augment the beauty of the painting. They can be obtained in many colors depending on the painting and the exhibit that is being currently shown.