The purpose of paper conservation or restoration
work is to preserve and restore works on paper and make them
accessible for exhibition, sale or study. Often, the works selected
for conservation treatment are aesthetically damaged, too fragile
for exhibition, or they are in imminent danger due to continuing
deterioration. Each art work has its own history of previous
treatment, framing, and environmental exposure, and consequently
the conservation and restoration of each individual work presents
a unique set of considerations. Galleries, collectors, and picture
framers might wish to be aware of some of the terminology, problems,
and possible treatments that may be undertaken by a paper conservator.
Some media, due to inherent flaws in the media
itself or due to environmental conditions, may start to crack
and flake off the paper. Without stabilization, the image will
continue to abrade with each handling. Flaking media should be "consolidated." Diluted
solutions of the consolidator could be applied locally with a
fine brush, feeding the material into the cracks and reattaching
the flakes of media to the paper.
Acidic cardboard and paper mounts (the acidity
is often caused by deterioration of wood pulp fiber in the paper)
eventually cause overall darkening and increasing fragility of
the paper support because of acid migration from the mount into
the original support paper. Acidic mounts may or may not be removed.
The severity of the deterioration being caused by the mount must
be weighed against the difficulty of removal and any historic
significance of the mount. A mount removal might involve delamination
of the cardboard by splitting between cardboard layers with a
microspatula, then removing the residual paper and adhesive with
steam. In certain cases, when the paper support is extremely
fragile, after the mount is removed, a new paper lining might
be attached using appropriate adhesives.
Pressure sensitive tapes (Scotch tape, masking
tape), gummed tapes and labels, paper patches, and various adhesives
on both the recto and verso of the pictures, will cause stains
that eventually migrate through the paper to show on the front.
Adhesive residues, tapes, and stains become increasingly difficult
to remove or reduce, and may become worse with time. Methods
for removal of tapes and stains are necessarily specific to each
work. The kind of tape, the type of paper to which the tape is
adhered, the length of time the tape has been in contact with
the paper, the intrusion of the tape into the design area, and
the amount of staining caused by the tape must all be considered.
The tapes and residual adhesive may be removed by a number of
methods, which include cutting off with a scalpel, lifting off
tapes or adhesives after softening with steam or heat, or by
local application or immersion in solvents. Adhesives which are
still tacky may sometimes simply rolled off with a soft eraser.
Before any treatment with a solvent is undertaken,
very small spot tests on both the paper and the media must be
conducted, to ensure that they will remain stable during the
procedure used to reduce the stain. The following methods may
be used:
-
Immersion of the entire sheet in a bath
of solvent helps to remove the tape (if it has not been previously
removed), the surface adhesive, and reduce stains that have
migrated into the paper.
-
A poultice consists of a solvent which dissolves
the adhesive and pulls the dissolved substance away from
the surface into the absorbent material.
-
A suction table is a mechanical tool which
pulls solvents through the stains to a blotter below.
The reasons for immersing a sheet of paper in
water are to remove some discoloration, water-soluble stains,
and to reduce acidity. The media and the paper must first be
spot tested to ensure that no harm will be done by immersion.
There are some works of art on paper which could benefit from
water treatment, but whose media (watercolors, pastels, charcoal)
are such that total immersion could cause some injury. These
works may be floated on the surface of the water, or be treated
in localized areas using poultices or the suction table.
Stains such as foxing (brown spots caused by
molds or my metal impurities left in the paper during manufacture),
matburn (the brown line caused by contact with an acidic mat),
some water stains, and mold stains may not be removed by immersion
in water. If these stains are very disfiguring, it may be appropriate
to use one of a variety of bleaching agents that have been thoroughly
tested and researched for use on works of art on paper. Sun/light
bleaching, and bleaching with chemicals such as hydrogen peroxide
or calcium hypochlorite, are possibilities given certain conditions
in the media and the paper. Any bleaching should be carried out
in a carefully measured and controlled environment and all necessary
precautions taken to be sure that any bleaching agent is neutralized
or washed from the paper.
Paper exposed to heat and ultraviolet light,
that has been in contact with poor quality materials, or that
has a high percentage of wood pulp fiber, may become darkened
and brittle. Deacidifying solutions can be introduced into a
paper by immersion, or by brushing or spraying on the solution.
Both aqueous and non-aqueous solutions are available and deposit
an alkaline reserve in the paper. This process helps to
-
neutralize the accessible acids present
-
prevent the development of acids in the future
-
ward off foxing
Previously mended tears may stain and distort
the paper in the torn area because of badly applied and poor
quality adhesives. Old mends should be removed and be replaced
with archival repairs. Tears left unrepaired may increase in
length, causing more damage as the paper is handled. Lacunae
(losses in the paper) which are left unfilled, are subject to
the same mechanical stresses as the tears. Tears may be mended
with wheat starch paste or methyl cellulose, reinforced with
Japanese tissue on the verso as necessary, or with archival heat
set tissue. Lacunae may be filled by inserting a patch of paper
which is close to the original paper in texture, weight, and
color, or with liquid paper pulp. Where the lacunae or tear intrudes
into the design, minimal toning of the repair can create a less
visually disturbing mend.
A paper may become weakened through contact
with other acidic materials, through inherent flaws in its manufacture,
by previous mishandling causing tears and structural weaknesses,
or by previous attachment to a poor quality mount. If the paper
is extremely fragile, it may be strengthened by lining (backing)
the sheet with a high quality Japanese or rag paper adhered with
an archival adhesive. The lined work is then dried under slight
tension or between blotters under appropriate weight to avoid
any cockling or distortion. In cases where the paper or media
should not be flexed at all, mounting to an archival secondary
solid support may be considered.
Severe cockling (rippling of paper, usually
caused by exposure to moisture) or creases may cause aesthetic
or structural problems, and the paper in a creased area may weaken
or tear if not reinforced. Cockling and other distortions may
cause abrasion of the image in areas which rub against another
work stacked above or against glazing material in contact with
the paper. Wrinkles and creases may be flattened by local application
of moisture to that area, followed by gentle pressure under blotters
and weights. When necessary, severe creases may be reinforced
on the verso with Japanese paper adhered with an archival paste.
Overall cockling of the paper (if not inherent to the work) may
necessitate relaxation of the paper with moisture, and subsequent
pressing between blotters under weight. If the media is too sensitive
for this type of flattening procedure, a special matting arrangement
(a more deeply cut window mat) might be helpful in protecting
the surface.
Where a crease, a tear, a lacuna, or an abrasion
intrudes into the image area, an aesthetic decision may be made
to tone the missing area to make it less visually disturbing.
The method used for inpainting (a term used to define the ethical
approach that any toning is in the area of loss only, does not
extend into the original media area, and does not alter the aesthetic
quality of the work) depends upon the media or the work.
|
Feature article by Philip Bareiss | 
By Appointment in Corrales | 505-280-4755