When framing a piece of art, the visible presentation, frame, liner or mats are the main focus and what goes on behind the scene is often overlooked. However the choice of materials and methods of securing the art is an equally important part to the overall framing project.
The whole purpose of framing art is to allow it to be displayed and be enjoyed. Most art however is fragile and easily damaged by the elements therefore the frame, mats, backing and glass provide a measure of protection while on display. How much protection needed is a combination of the art’s media and substrate materials, the actual or perceived monetary value and/or the non-monetary value placed on it by the owner.
Generally if the art is an original or is highly valued, conservation or archival methods would be used.
For these purposes 100% rag acid free backing materials would be used.
For art on paper the mounting would use reversible acid free hinges, either special tapes or hand torn rice paper with acid free paste. The hinges would be applied to the top only to allow for expansion or shrinkage and be strong enough to hold the art in place but week enough to break before the art tears if dropped.
Art on canvas would be streatched on wood bars using brass or stainless staples and normally does not require glazing and the back should remain open to provide air flow although a paper dust cover with openings could be used on the framed.
Reproduction pieces of lower value are commonly mounted with wet or dry glues or with non archival hinges which are not normally reversible . The backing materials do not need to be 100% rag however should still be acid neutral [buffered to a neutral ph] which helps in the longevity of the artwork.
Needlework art like canvas requires stretching. The material used in mounting would still be 100% acid free and rather than staples, cotton thead is used to to hand lace the work to the backing.