Works of
art and documents on paper are easily torn, folded, and smudged.
They are also susceptible to chemical damage by components contained
in paperboard and adhesives used to mat works of art and documents.
The use of chemically unstable products can result in damage
to the art or documents that they are intended to protect. Choosing
appropriate mat board, hinges, glazing, and backboard will help
to protect and preserve the works in your collection. Choosing
a framer with strict conservation standards is key. Ask questions
first!
Mat Boards
Many
of the mat boards available for framing purposes are of
poor quality. These are fine for inexpensive posters that
you pick up, but just realize that this mats will damage
what they touch over time. The acidic content of these
inferior boards can cause paper to become brittle and
darken. In poor quality mat boards, the core of the board
darkens as it ages. When this exposed core of the board
comes into direct contact with the matted work, at the
window opening or at the edges, an orange-brown line of
staining, known as "mat burn" occurs. To prevent
this problem, use chemically stable materials for both
the window mat and the back mat. Ask for mat boards that
are alkaline and made fully from cotton rag or 100% chemically
purified wood pulp. Chemically stable boards generally
have an alkaline reserve (often referred to as a "buffer")
incorporated to neutralize acidity from atmospheric pollutants
and from the artifact itself. Some photographic and printing
processes are "alkaline sensitive" and may be
adversely affected by buffered materials, particularly
in a humid environment. In these cases, pH neutral "unbuffered"
materials may be more appropriate. Look for materials
that explicitly meet the International Organization for
Standardization specifications for enclosures. |
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| Hinges
Japanese paper hinges are used to attach a work
of art or document on paper to its back mat. These
hinges are attached to the reverse of the work with
a cooked, highly purified wheat starch paste. They
secure the top edge of the work to the mat, while
still allowing the paper to expand and contract
freely in response to changes in its environment.
Directly adhering the corners of the work to the
back mat without hinges can cause staining, buckling,
or tears in the paper support. Another method of
hinging uses "photo-corners," triangular
sleeves of paper or inert plastic film placed over
the object's corners and adhered to the backmat.
No adhesive is applied to the artifact when using
"photo corners," facilitating its removal
from the backmat, if necessary. Avoid methods of
attaching works of art to back mats such as dry-mounting,
lamination, spray mount, rubber cement, or pressure-sensitive
tapes (e.g, masking, office, or even those referred
to as "archival" or "preservation"
tapes). The adhesives in these materials can seep
into paper, become discolored, brittle, and difficult
to remove. There are some "conservation"
dry-mounting materials, but you should not use these
on items of value. |
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Backing Boards
The
backing board is a rigid sheet of chemically stable
board placed behind the backmat in the frame. It
is stiff enough to hold the contents of the frame
in place without bowing when displayed. These boards
are to be made from chemically stable papers and/or
plastics and adhesives, and occur in such formats
as corrugated, honeycombed, and foam boards. To
minimize the effects of pollutants and changes in
relative humidity, some conservators recommend the
placement of a layer of impermeable material, such
as polyester film (e.g., Mylar Type D) or a plastic-aluminum
laminate (such as Marvelseal), between the back
mat and the backing board, or outside the backing
board. |
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Glazing Materials
Glazing
protects the surface of the work of art and prevents the
infiltration of dirt and dust. The two most common glazing
materials are glass and acrylic sheet. Plastics other
than acrylic may be unstable and are to be avoided. An
acrylic sheet weighs less than glass and is shatterproof.
Although acrylic tends to scratch, scratch-resistant grades
are available. Because acrylic has a static charge, use
glass when glazing powdery materials such as pastel, chalk,
and charcoal. Whether you choose glass or acrylic, always
be sure that the glazing material does not come into direct
contact with the surface of the artifact. Prolonged contact
of the glazing with the surface of the artifact can result
in its adhesion to the glazing, or can cause surface changes
in the work. A thick mat or a spacer in the frame will
keep the artifact from touching the glazing. Glazing that
filters ultraviolet radiation can help reduce the fading
of colors or darkening of paper. Both glass and acrylic
sheet that filter out ultraviolet radiation are available.
Works glazed with ultraviolet filtering materials can
still be damaged by high light levels and long periods
of exposure. Limit the quantity of light and the duration
of exposure to light to minimize damage to documents and
works of art on paper. And don't use picture lights on
important pieces! |
Summary
•Have
items matted with chemically stable window and back mats.
(At least 4 ply in thickness; alkaline—pH 7.5–10,
100% cotton rag or chemically purified woodpulp)
•Ensure that mats are always larger than the item
being matted.
•Have the window and back mat attached along the
top or left edge (which ever is longer) with gummed linen
tape. (The gummed linen tape touches ONLY the mat board,
not the object.)
•Have the work hinged to the back mat with Japanese
paper and wheat starch paste or with photocorners as a
primary means of attachment.
•Select an appropriate glazing material to be placed
in the frame in front of the matted work. Include additional
spacers as needed to separate matted work from contact
with the glazing material.
•Have chemically stable backing board placed into
the frame behind the matted work.
•Have a dust seal placed on the very back of the
frame. Dust seals may be made from chemically stable paper
or polyester film. |
Resources/Further Reading
American Institute for Conservation. "Works of Art on
Paper" (brochure). Washington D.C.: American Institute
for Conservation of Historic and Artistic Works, 2001. http://aic.stanford.edu/library/online/brochures/matt.html
Clapp, Anne F. Curatorial Care of Works of Art on Paper. New
York: Nick Lyons Books, 1987.
CCI Note. "Matting Works on Paper," Ottawa, Canada:
Canadian Conservation Institute, 1997.
Ellis, Margaret H. The Care of Print and Drawings. Nashville,
Tenn.: American Association for State and Local History, 1987.
Reprint. Walnut Creek, Calif.: Altamira Press, 1995.
Ellis, Margaret H. “Works of Art on Paper.” In Caring
for Your Collections, ed. Arthur Schultz. New York: Harry
N. Abrams, 1992. pp. 40–51.
Perkinson, Roy L., and Francis W. Dollof. How to Care for
Works of Art on Paper. Boston: Museum of Fine Arts, 1985.
Phibbs, Hugh. “The Hinging of Works of Art on Paper”
Preservation Hinging, Picture Framing Magazine, Feb. 1994.
Smith, Merrily A., comp. Matting and Hinging of Works of Art
on Paper. Washington, D.C.: Library of Congress, 1981.
Revised 2001 by Elizabeth Kaiser Schulte, Hilary A. Kaplan,
and Chris Foster
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