INTRODUCTION
They are the unsung heroes of iconic
ideas forming the bedrock of civil
society. Using ink brewed from iron
and extract of oak galls, they committed
to parchment in a fine, flowing
hand the edicts of kings and the
hope of nations. The documents that
have survived them are the physical
embodiment of not only astonishing
thought, but also of the more mundane
details of law, commerce, and convention.
Those unnamed scribes and clerks
from centuries ago probably had little
clue that their painstaking work would
be the window through which subsequent
generations could seek understanding
of who we were and what
we might become. They would also
most assuredly be amazed at the tools and technologies now deployed to keep
those windows clear and open for the
foreseeable future.
The most cutting edge of these techniques
are currently being implemented
to protect one of the four remaining originals
of the 1297 Magna Carta for a new
permanent exhibit slated to open March
2012 in the West Rotunda Gallery of
the U.S. National Archives Building.
"Working with a very significant document
such as the Magna Carta creates
a big responsibility to make sure
everything is planned and carried out
correctly down to the smallest detail,"
said Catherine Nicholson, deputy director of the Document Conservation
Division, National Archives and
Records Administration (NARA) and
project manager for the Magna Carta
encasement initiative. "But, the reward
is the sense of pride in helping to make
such an important document last as long
as possible. To get to handle a document
that was written more than 700 years
ago is amazing."
THE JOURNEY TO AMERICA
The original Magna Carta was issued
in 1215 when an assembly of aggrieved
barons forced King John of England to
write down and confirm with the royal
seal that he and his heirs would recognize
traditional liberties. Modified versions
of the Magna Carta were reissued by
each of King John's successors, with the
1297 iteration, confirmed by Edward I,
being significant as the first Magna Carta
entered into the official Statute Rolls
of England, marking its transition from
a brokered agreement between the king
and his feudal lords to the foundation of
English law.
The majority of the original
Magna Carta's clauses have long since
been repealed because they focused on
addressing specific feudal customs and
other controversies of the day. Its lasting
legacy, however, has been in establishing
fundamental principles of a free
society—that a government leader's authority
is not above the law and "no free
man shall be seized or imprisoned, or
stripped of his rights or possessions, or
outlawed or exiled . . . except by the lawful
judgment of his equals or by the law
of the land." Its echoes resonate through
everything from the U.S. Constitution
and Bill of Rights to the Universal Declaration
of Human Rights adopted by the
United Nations in 1948.
The 1297 Magna Carta currently
undergoing conservation treatment at
NARA had languished for years in a
damp English castle before its significance was recognized in the last century.
The historic sheet held up remarkably
well through the ages, said Nicholson,
"surviving by the good fortune of being
stored in a place that mostly protected
it from vermin, fire, floods, and excessive
handling and exposure to light." Its
2,500 words were penned in medieval
Latin with ferrogallotannate, or iron gall,
ink.
As was typical in 13th century England,
the charter was inscribed on parchment
made of animal skin soaked in a
lime bath, dehaired, and then stretched
on a frame to dry. While the skin was
scraped to create a smooth writing surface,
the parchment was tough and difficult to work with, necessitating that mistakes
or modifications be scratched out
with a knife. A unique aspect of this particular
Magna Carta is its honey-colored
wax seal suspended by a narrow strap
of parchment laced through a folded
flap at the bottom of the document. The
wax bears the central part of the Seal of
King Edward I, showing him seated on a
throne.
The Perot Foundation purchased the
ancient document from a British family
in 1984 for $1.5 million, subsequently
loaning it to the National Archives for
display in 1985. The only original Magna
Carta located in the United States, its
new abode was a sealed metal box with
an acrylic cover bolted against synthetic
gasketing. The box was then filled with
inert gas that was humidified and replenished
every year or two to preserve the
document and keep the animal skin from
warping.
In 2007, the Perot Foundation terminated
its loan with the National Archives
and put its Magna Carta on the auction
block. David Rubenstein, co-founder of
the private equity firm, Carlyle Group,
was concerned that it would end up in a
private collection, never to be seen again
by the public. Arriving with just minutes
to spare at Sotheby's, New York, on the
day of the auction, Rubenstein placed
the winning bid of $21.3 million for the
charter and then immediately announced
that it would return to the National Archives
on loan from him as a gift to the
American people. Rubenstein is also
underwriting the cost of ensuring the
Magna Carta's continued longevity with
state-of-the-art encasement technology.
TIMELESS AND TIMEWORN
Shortly after its last day for public
viewing on March 1, 2011, the Magna
Carta was transported to an undisclosed
location where a team of conservators
(Figure 1) began poring over every centimeter
to determine its condition and
develop a treatment plan. Their work, as
Nicholson describes it, seems "an amazing
combination of science and art."
Over the next year, they will evaluate issues
such as moisture sensitivity, material
composition, and possible reactions
to proposed conservation treatments
and encasement. In terms of repair, any
small holes resulting from materials
degradation or the appetite of a long ago
insect will be filled with meticulously
shaped handmade Japanese paper toned
to match the original document. While
some ink has been lost to dripping water
over the centuries, no attempt will be
made to "rewrite history" by replacing
even a single period. However, with a
camera employing ultraviolet radiation,
remnants of writing invisible to the naked
eye will be revealed by ultraviolet
fluorescence and photographed.
Nicholson said among the Magna
Carta's greatest preservation challenges
is its potential to expand, contract, and
distort from its sensitivity to changes
in moisture content. The iron gall ink is
also highly susceptible to fading under
light.
Since storing the Magna Carta in the
dark, away from all possible environmental
encroachment is not an option,
Nicholson is working with a team of
fabrication specialists at the National
Institute of Standards and Technology
(NIST) under a Memorandum of Agreement
to design and construct an encasement
that offers the next best thing.
Nicholson said that the choice of a tightly
sealed metal encasement filled with
inert gas will prevent photo-oxidation
of the ink, while an approach to carefully
monitor and control the amount of
humidity will keep the parchment from
distorting. The new encasement, she
noted, will necessitate changes in how
the Magna Carta had been displayed
in the past. "The previous display supported
the document on a linen-covered
window mat, assembled with pressuresensitive
adhesive," explained Nicholson.
"In a very tightly sealed box, the
goal is to avoid organic materials such as
linen or adhesives that can release volatile
gasses, such as acetic acid, into the
sealed atmosphere. The concentration of
these gasses can grow over time inside
the sealed box and cause deterioration."
THE LEGACY OF THE
CHARTERS PROJECT
The encasement solution being developed
for the Magna Carta is based,
in large part, on technology that NIST
pioneered for the 2003 re-encasement of
the U.S. Constitution and Bill of Rights
and the Declaration of Independence,
collectively known as the Charters of
Freedom (Figure 2). Prior to that initiative,
the documents had been displayed
for more than 50 years in helium-filled
encasements developed by the National
Bureau of Standards, the predecessor
agency to NIST.
"The original Charters encasements
were an elegant solution to providing
a protective enclosure with a low oxygen
level," said Charles Tilford, retired
NIST physicist and a member of the
Charters project team. "They were an
inexpensive adaptation of a commercial
product—thermopane windows—that
used a proprietary process to apply a
very adherent copper coating to the perimeter
of a glass sheet. This allowed
the encasements to be assembled by
soldering the edge of the glass to a lead
strip that separated the two pieces of
glass, providing a 'hard' seal that resulted
in negligible intrusion of air over half
a century for five of the seven encasements."
Clever and groundbreaking for its
time, this particular solution still had its
drawbacks, such as soldering with the
documents inside the encasement. Said
Tilford, "A low-temperature solder and
a very skilled Libbey-Owens-Ford factory
worker allowed the assembly to be
done very quickly with minimal heating,
but any risk of overheating is no
longer acceptable." In addition, the helium
that filled the encasements diffused
slowly through the glass, and apart from
a "primitive leak detector," according to
Tilford, no instrumentation was used to
monitor the conditions inside the container.
While the documents themselves
faced the test of time fairly well, the encasements
did not. Imaging technology
adapted from the U.S. space program
by NASA's Jet Propulsion Laboratory
revealed that the glass had microscopically
deteriorated, with minute crystals
and microdroplets of liquid forming on
the glass surfaces. This not only meant
that the damaged glass would slowly
become opaque over time, but it also
indicated a build up of potentially damaging
humidity inside the encasement
environment.
An important lesson learned from
the aging encasements was the need
for flexibility. The new Charters of
Freedom encasements, as well as the
evolving Magna Carta encasement, can
be opened and resealed to replace deteriorating
parts and allow for conservation
treatments on the documents. Also
integral to the design is sophisticated
instrumentation monitoring the slightest
variation in temperature, humidity, and
oxygen so that adjustments can be made
before problems emerge (Figure 3). Instead
of helium, humidified argon gas is
now used to flood the encasements. It's
a natural choice for this use, said Tilford,
because "it is completely inert, very
pure, inexpensive, and does not diffuse
through glass."
The encasements also needed to be
light, but strong, to allow for easy, safe
transportation. Advanced fabrication
techniques were used to create each
Charters of Freedom encasement from
a single block of aluminum, while titanium
was chosen for the frame (Figure
4). "The selection of titanium was motivated
in part by its strength and light
weight, but it also had public relations
appeal—titanium was the high-tech material
of that time," said Tilford, noting
that carbon composites might be considered
today for similar reasons. Because
the specifications for the Charters project
dictated that the seals last for a century,
a highly corrosion-resistant nickelchromium
alloy was used for the seal
material (Figure 5).
Specific materials and approaches for
the Magna Carta encasement are still being
explored, said Mark Luce, NIST director
of Fabrication Technology Management
Resources, noting that maintaining
the inside environment through
a passive system is the principle driving
the design. This approach, according to
Luce, will greatly reduce the staff time
needed for monitoring the encasement
environment, as well as the frequency
of replenishing the humidified inert gas
sealed inside, giving the document more
consistent protection over the long term.
Of crucial importance, he said, is "the
type, quality, and placement of the encasement
seal."
At this point in the project, NIST has
proposed the use of elastomer seals,
rather than the metal C-seal used for the
Charters of Freedom. "Experience indicates
that these elastomer seals should
last at least 20 to 25 years, although the
quality of the seals might eventually fail because of stiffening of the synthetic
polymers," said Luce. In the event that
this would happen, the encasement
can be opened and the seal replaced.
Luce said that the groove for the seal is
being designed so that it could accept a
drop-in replacement of a metal C-seal,
if that seemed like the better option at
that time.
MAPPING NEW
DIRECTIONS
The current Magna Carta encasement
design on the table uses two Oring
seals around its circumference.
Luce said this approach will reduce
the infiltration of potentially harmful
oxygen, while also allowing for periodic
measurement of gas leakage by
testing for helium tracer gas in the space
between the seals. Although Luce is
building on the technology developed
through the Charters of Freedom project,
he is also drawing from his experiences
as the project leader for the 1507
Waldseemüller map encasement.
Now on display in the U.S. Library of
Congress, the Waldseemüller map (Figure
6) was the first world map known
to label the New World as "America,"
earning it the nickname of "America's
birth certificate." Sharing similar materials
degradation issues with the Magna
Carta and the Charters of Freedom, the
Waldseemüller map also added its immense
size—40 square feet—to the list
of encasement challenges (Figure 7).
Luce said that concerns included developing
a hermetic seal that could function
effectively over the large surface
and designing an encasement system
that could absorb atmospheric pressure
changes involving the volume of so
much inert gas. Weight was an issue,
too, since the encasement could not exceed
existing floor load limitations.
Using lightweight aluminum for the
encasement's frame and base partially
addressed the map's potential weight
problems. Elastomer seals, like those
proposed for the Magna Carta, resolved
some of the map encasement's design
issues, while giving rise to others. "For
metal seals, such as used in the Charters
encasements, periodic measurement
of helium leaking into the space
between the seals from the interior of
the encasement can be converted to a
reliable measure of the rate of oxygen
permeation and a check on the continued
integrity of the seal," said Luce.
"For elastomer seals, the conversion
from measured helium leak rate to actual
oxygen leak rate depends on the
material properties of the seal and is
much more uncertain."
In devising a solution, Luce said
that NIST employed an in situ oxygen
sensor to directly measure oxygen
permeation. Attached to the outside
of the encasement. but pneumatically
connected to the interior, the sensor
has parts per million sensitivity and
does not use liquids or oxygen adsorbing
materials, eliminating concerns
for potential destructive interactions
with the map material. The system has
worked so well for the Waldseemüller
map that NARA has approved a similar
approach to be incorporated into
the Magna Carta encasement.
"Most of the materials, components,
and techniques used in encasement
construction and conditioning
are used extensively at NIST and
many of them have large-scale industrial
use," said Tilford. "The encasements
do represent new applications
with their own set of issues (Figures 8,
9, 10). Fortunately, NIST has experts
with a wide range of knowledge and
experiences who are used to working
on new challenges and recovering
from unexpected problems."
When the Magna Carta returns to
the West Rotunda in 2012, its delicate
parchment will offer another story beyond
the words scratched on its surface.
It is one of a truly amazing journey
from the poorly lit confines of a
scribe's quarters, to medieval castles
and meeting places, to laboratories
crammed with equipment usually reserved
for use in cutting edge industries.
Its passage from one set of hands
to another in service of its protection
is a testament to how far society has
come since it was first written—and
symbolic proof that the will of talented
and persistent people will never
permit a great idea to fade away.
Lynne Robinson is a news and feature
writer for TMS. |