Prologue Magazine

Fall 2003, Vol. 35, No. 3

A New Era Begins for the Charters of Freedom
By Mary Lynn Ritzenthaler and Catherine Nicholson

close-up of conservator working on Constitution
A conservator examines the ink on Page One of the Constitution, letter by letter. In the treatment of this document, the most important step was to ensure that the original iron gall ink remained well adhered.

The nation's founding documents, with their timeless messages of liberty and freedom, are now ready for the twenty-first century.

The Declaration of Independence, the Constitution, and the Bill of Rights - which laid out the reasons for revolution, the framework of a new government, and the rights of individuals - have been returned to the National Archives Building's historic Rotunda in Washington, D.C.

These documents, known collectively as the Charters of Freedom, were removed from display on July 5, 2001, and have undergone long-planned conservation treatment and are sealed in new state-of-the-art encasements before being returned to the Rotunda.

The conservation work and re-encasement of the Charters of Freedom had been discussed for years at the Archives. The long-awaited renovation of John Russell Pope's 1935 landmark building provided the opportunity to make the Charters ready for the new century.


For almost fifty years, the Declaration, the Bill of Rights, and pages 1 and 4 of the Constitution had been on continuous display, sealed in glass and metal encasements filled with the inert gas helium, with an additional loose sheet of glass resting directly on the parchment. The encasement glass was beginning to show evidence of deterioration, which would eventually affect the visibility of the documents. This glass deterioration was a serious concern because it also indicated that the environment within the encasement was more humid than intended.

The design of the encasements did not permit easy access to the documents, since the encasements could not be opened and resealed. Advances in techniques for mounting parchment for exhibition and a greater understanding of materials also argued for removing the Charters of Freedom from the encasements that had protected them for fifty years. All of these conservation and scientific factors led to the decision to re-encase the Charters.

A multiyear collaborative project resulted, involving National Archives staff as well as scientists and technical experts from the National Institute of Standards and Technology (NIST) and other agencies and organizations. Now at the completion of the project, the Charters of Freedom are protected in new state-of-the-art encasements. But this story begins with the first critical moment of opening an encasement to reveal a historic sheet of parchment that had been sealed in inert gas for fifty years.


Science in Support of History

Opening an encasement was a step in a process that began more than twenty years ago with questions raised about the safety and stability of the Charters' encasements.

In 1982 the National Archives invited a panel of respected scientists and preservation professionals to assess the preservation needs of the Charters of Freedom. They advised comparing images of the Charters made at intervals over time to look for changes that might raise concerns.

The National Archives turned to the Imaging Processing Lab at the Jet Propulsion Laboratory (JPL) to assist in this effort. Borrowing technology from America's space program, the JPL developed an imaging system like that used in space exploration. The resulting Charters Monitoring System (CMS) created digital image files by scanning one-inch squares on each document.

During imaging, the encased document lay on a tabletop with legs that floated on nitrogen in cylinders, which acted as shock absorbers to eliminate vibration. An overhead charged-couple device "camera" captured the relative brightness of 1,024 lines of 1,024 pixels in each patch through glass layers, using precise positioning to allow return to the exact spot in future scans.

The National Archives received the Charters Monitoring System in 1987. Conservation staff made baseline measurements for patches on the pages of the Charters. In following years, patches were re-scanned and compared pixel by pixel to the baseline image, looking for physical changes.

In 1996, after more than 125 scans, staff reported the findings. The CMS did not reveal feared changes in ink intensity or loss of ink. In all the scans on the seven encased documents, just one insecure flake of ink was noted on a raised ridge of parchment on the Transmittal Page of the Constitution.

But if the ink of 1787 was holding its own, the encasements of 1951 were not.

The CMS space-age technology ultimately confirmed findings made in 1987 with the microscope: minute crystals and microdroplets of liquid were found on surfaces of the two glass sheets over each document. The scans confirmed that these changes in the glass progressed between 1987 and 1995. Conservators using a binocular microscope could see crystals and liquid droplets on the glass surfaces. These signs of glass deterioration were a clue to the relative humidity inside the encasements. Glass deteriorates at a relative humidity greater than 40 percent. But the encasement helium had been carefully humidified to 30 percent. This low humidity was intended to minimize parchment hydrolysis, a chemical term that means "water cutting." The CMS scans confirmed evidence of progressive glass deterioration, which was a major impetus in deciding to re-encase the Charters of Freedom.


Opening the 1950s-era Encasements

Opening the encasement and liberating the first parchment after fifty years was a step fraught with some uncertainty and concerns. The document was being freed to allow needed examination, treatment, and testing. The project was breaking new ground, but at the same time undoing beautiful craftsmanship that had achieved hermetic seals in 1951 and protected the parchment from damage and deterioration. There was no manual that told how to open the encasement and no way to know if unexpected problems would arise in doing so.

The original encasement design was elegantly simple: two sheets of glass with metallic copper flashed on the edges, soldered to a lead ribbon that bridged the 3/8-inch gap between the glass. Between the glass sheets, the historic parchment lay on several sheets of handmade paper, surrounded by a brass collar. A third loose piece of glass rested on the parchment surface to restrain it and help keep it flat.

First to be opened was the encasement that held the Transmittal Page of the United States Constitution. This document was the parchment letter of conveyance accompanying the Constitution, not strictly part of the Constitution but signed by George Washington as President of the Constitutional Convention. The successful opening of this encasement would permit the conservation staff to test and refine techniques and procedures before proceeding to the encasements containing the four pages of the Constitution, the Declaration of Independence, and the Bill of Rights.

However, the intriguing question persisted of what was inside the encasements after fifty years: air, helium, a mixture, or a vacuum? Helium is so small a molecule that it escapes slowly through some types of glass and very readily through the smallest hole. The leak detectors connected to each encasement indicated that air had not infiltrated in. But would the leak detectors work in a vacuum if the helium had escaped?

To answer these questions, special procedures were developed to sample the gas inside each encasement before it was opened and lost forever. After removing the brass frame and before each encasement was opened, an extremely small puncture was made in the seal to permit extraction of the interior atmosphere. This was done to permit analysis of the interior gas (to determine what percentage of helium remained) and thus how well the encasements had functioned. Once this gas was analyzed, the large amount of helium present gave further proof that the original encasements had functioned as designed and engineered.

The conservator used a small sharp blade to probe and enlarge the pinprick hole of the gas penetration site to permit the insertion of a larger tool that could cut through the soldered lead seal. With a rocking motion, the blade sliced the lead cleanly, sometimes leaving long curling flourishes of lead in its wake. Only in the areas of excess solder around the leak detector was the process difficult and time consuming.

Finally the deed was done: the two conservators slowly and carefully lifted away the glass that had covered the parchment for fifty years. Care was taken to ensure that the parchment did not adhere to the glass and also to confirm that no flakes of ink were present on the inner surface of glass that had been in direct contact with the parchment. It was a momentous if quiet success, with no evidence of ink on the glass and no alteration to the parchment as a result of opening the encasement. The parchment and the backing paper upon which it rested were immediately secured in a custom box to permit slow acclimation to room conditions and await later examination, while the remaining sheets of backing paper were quickly sealed in special airtight bags to permit subsequent analysis.

Over the next three years, conservators repeated this process of opening encasements. The encasement openings were scheduled to leave the parchment documents sealed and protected in an environment of inert gas for as long as possible, to minimize each document's exposure to oxygen, because organic material like parchment can react with oxygen and undergo deterioration. After opening an encasement, conservators carefully stored old encasement components to permit later study. Then attention could turn to the document itself.


Examining the Documents

As a document was freed from its encasement, it became available for close examination, measuring, and photography without the barrier of intervening layers of glass. While some records exist on the creation, history, travels, and exhibition of the documents over the years - including a few nineteenth- and twentieth-century photographs - the information is relatively sparse. But the documents themselves offered a wealth of clues and insights into the ways they were created and handled. Patterns of creases and folds on the documents pointed to how they had been folded or stored.

The Bill of Rights still had pronounced horizontal and vertical creases from having been folded, though it had been stored flat for almost a century.

The Declaration had both fold lines and parallel horizontal creases that were evidence of rolling. It also had a noticeable band along all edges that was flat and very clean. Records indicate that early in the twentieth century the Declaration had been glued along the four edges to a support.

The Constitution did not show evidence of folding but had adhesive in broad strokes on the backs of the parchments, suggesting that the leaves had been glued overall to a backing.

Each document was available for direct examination for a short time before re-encasement, but this time was sufficient to apply modern examination techniques and tools to evaluate and record the document's condition and develop and carry out appropriate conservation treatment. The full dimensions of each parchment were measured as well as its average thickness, which varied somewhat along the edges and from top to bottom. The color of the parchment was measured. Many photographs were made of the condition of the parchment before any treatment was proposed or undertaken.


How the Charters Were Made

The Declaration of Independence, the Constitution, and the Bill of Rights were handwritten by a clerk or scribe on parchment, an animal skin specially treated with lime and stretched to create a strong, long-lasting writing support.

The clerk's job was a demanding one. He was trained to create a fine handwritten text. In his work, he wrote a very regular and legible cursive script, with titles and important phrases engrossed, that is, made larger and darker with additional strokes of ink. His tools included a pen knife and quill pens cut from large feathers. He wrote with ink made from oak galls and iron, with gum arabic as binder, and often with a colorant such as logwood added to enhance the initially pale ink. Following English practice, he wrote important legal documents and contracts on parchment. Parchment was expensive, generally imported from Great Britain, but its life expectancy was very long.

The clerk often had little time to take a corrected rough draft and write out a "fair" or "smooth" final legible copy before it was to be signed. He needed rule lines to guide his hand and ensure straight lines of text. Corrections were difficult to make because parchment was such a tough and unforgiving medium. He scraped out words or lines with his penknife or inserted words or phrases carefully into the text, sometimes including an errata paragraph to attest that the approved document was unaltered.

The clerk could never have imagined that two centuries later, conservators would peer through a binocular microscope to examine his pen strokes. Examining these documents, conservators found faint rule lines that were present on several, appearing as reddish brown lines on the Constitution and a gray medium on the Declaration. They saw several scraped erasures on the documents, visible as areas of roughened parchment often grayed with surface dirt, and occasionally, omitted words or phrases inserted into the text. On the last page of the Constitution, the scribe wrote a final errata paragraph noting his corrections to the text. Many random ink splotches or spatter, large and small, show evidence of the difficulty of writing with a quill pen.

Working closely with the documents, conservators also came to recognize the characteristic handwriting of the different scribes who wrote these three documents. They also saw unobtrusive marks or annotations on the documents, including small numbers, an "x" mark, and brackets in the margins, presumably to mark or emphasize a section of text. Who made these marks and when is not known. Most of these faint marks appear to be in a soft gray medium that resembles graphite.

Assessing Condition and Making Treatment Decisions

More than two hundred years later, conservators in the no longer young nation examined the penmen's work to determine its condition. While the text on the whole mostly remained legible, under the microscope they could see where small flakes of ink had disappeared and other lifted flakes were tenuously attached. The once flat parchment, responding to changes in moisture and humidity, now undulated in many cockles or "hills and valleys." In the past, insects had nibbled the parchment, leaving lacey vulnerable edges on some sheets.

Conservators selected and proposed treatments to address these condition problems in each parchment document. The approach to treatment was conservative, designed to stabilize the parchment and preserve the legibility of the text. These were not documents on which to try a brand-new approach or apply new chemicals that had not stood the test of time. Nor was it appropriate to undertake any alteration of the significant text. Where ink flakes had been lost, it was not ethical to alter the content of a single line or change a single punctuation mark. The important task was to secure and preserve the ink that remained and thus the content of the text.

Some cuts or puncture holes were present that might look like damage but were in fact evidence of historical techniques used on the documents. Six one-inch vertical slits along the top edges of each page of the Constitution were cut with a sharp knife to allow the lacing of a ribbon to bind the leaves together. While they had been repaired in the past, the slits showed how the document leaves originally may have been secured together, so the conservators proposed removing the old repairs and leaving the slits open after treatment. Similarly, extremely small puncture holes deliberately made with a tool near the slits were also left in their original state and not repaired.

On the Declaration, close examination revealed small Y-shaped puncture holes regularly spaced along most edges. These punctures suggest that at some time in the past the parchment was stretched in a string mount to keep it flat and taut. Several edges of most of the parchments showed varying amounts of accumulated grime. This grime was an excellent indicator that the dirty edges were original. The lack of heavy grime on other edges suggested that trimming had occurred in a more recent era. Some edges, ragged and lacking grime, also indicated recent trimming with a less than sharp tool. None of this trimming, however, came near or endangered the text. All of these features would be noted in the permanent record of condition examination.

The first important steps were to conduct a condition assessment and write a detailed condition report on all that could be seen in examining the document. A treatment proposal was then written, outlining the exact procedures proposed to address the condition problems. Of the three documents to be treated, only one, the Declaration, had detailed records of previous treatment undertaken in 1942.

One of the legacies of the current project would be to leave detailed reports on condition and treatment, extensive photographic documentation, and results of scientific study and analysis. Therefore, the treatment proposal also included methods for taking microscopic surface samples of parchment to be used in scientific studies of the condition of the parchment. In addition, it was proposed to remove minute samples of ink from areas of spatter or smears that were not part of the text itself to verify the composition of the ink present. Because access to the documents would be limited after they were resealed in the new encasements, it was important to answer questions that remained from the 1942 treatment and to anticipate questions that future caretakers might have about these documents. After the treatment proposal was signed, which conveyed approval and written permission to proceed, treatment commenced.


Conservation Treatment Steps

The conservators' first step was to stabilize any lifting or insecure ink flakes with parchment size, a traditional gelatin adhesive made by cooking parchment scraps. Looking through a binocular microscope, the conservator guided the fine tip of a 0000 watercolor brush to apply droplets of size no larger than the period at the end of this sentence. The adhesive flowed under the ink flake, causing it to move back into its original position. This step was the most time consuming part of the treatment, as each line of text was examined, letter by letter, line by line, looking for flakes of ink that appeared insecurely attached.

Once the conservators had examined and secured the ink on the front, they could finally turn the parchment over to see the reverse. While the fronts of the documents had been visible in the glass encasements, layers of paper behind each parchment obscured the backs. Now the backs of the documents were visible. While there were no great surprises, random ink splotches and partial grayish hand and fingerprints were found on the backs of the Constitution pages.

The only text revealed was on the reverse of the Declaration, which has "The Original Declaration of Independence July 4th 1776." inscribed parallel to its bottom edge. This inscription, known from photographs from the 1940s, probably served as a label that could be read when the document was rolled up for storage.

Proceeding with treatment, the conservators gently cleaned dirt and grime in bare areas of parchment - taking special care to avoid disturbing original rule lines and other intentional marks. They removed old adhesive on the parchment that distorted the parchment sheet and made it resist lying flat.

The parchment was sandwiched between layers of a synthetic material that permitted the introduction of humidity to relax the skin fully. Then it was was dried under tension to return it to a flat plane. In this process of flattening, the challenge was to make the parchment limp without softening the ink so that it could be realigned to remove the distortions of many decades. The Declaration of Independence was the only parchment that was not humidified and flattened in this way. Compared to the other Charters documents, it had been more damaged by frequent handling and exhibition, and scientific study of the parchment confirmed that it was vulnerable to moisture. As a result, less treatment was carried out on the Declaration. Since it had received extensive treatment in 1942, it was already relatively flat, and its ink did not show vulnerable flakes that needed consolidation.

Declaration edge, before treatment Declaration edge, after treatment
The image at left shows loss in the edge of the parchment near the word "America" on the Declaration of Independence. At right is the same area after conservation treatment. The loss was filled with a small piece of Japanese paper that was toned and burnished to resemble the parchment. With the loss filled, the edge of the Declaration is stable and visually intact.

Where parchment edges had been lost to insects or physical damage, unobtrusive repairs were made with a handmade Japanese paper that closely matched the original parchment in color and thickness, with parchment size as adhesive. These repairs would protect the vulnerable edges from snagging or curling and suggest the original rectangular shape of the documents.


Looking to the Future

As the project ends, the conservators think about what has been accomplished and the tasks ahead. The physical nature of the Declaration of Independence, the Constitution, and the Bill of Rights has been examined, documented, and treated - and the documents placed in new handsome, technologically advanced encasements.

The new encasements, which look like large, deep picture frames, were constructed by NIST of titanium and aluminum. The frames are gold plated to evoke the style of historic frames. Inside each encasement, the parchment document rests on a metal platform with a cushion of handmade paper. The paper acts to absorb or release moisture in the event of temperature or humidity changes inside the encasement. Polyester tabs secure the parchment documents to the platform.

The encasement design includes a pair of sapphire windows in the top edge that permit a light beam to travel a path below the document platform, reflected by precisely positioned mirrors. Using a new optical instrument to compare and detect characteristic absorption of certain wavelengths in the exiting light beam, conservators and scientists in the near and long term will be able to determine the relative humidity and the oxygen content of the inert argon gas environment within the encasements. Any changes (such as the presence of oxygen) that could have a detrimental effect on the documents will be cause to start the cycle again - to break the seals that should last much longer than one hundred years and again expose these historic parchments to the air. Looking ahead raises the question of how long this work will hold and what new tools will become available to preserve these documents in the future.

Far sighted as they were, the Framers could never have dreamed of the steps that future caretakers would take - and the amazing space-age tools and technologies brought to bear - to ensure the preservation of their words written on parchment in the last decades of the eighteenth century.

While some may argue that these documents are mere musty parchments - old ink on old parchment - the ideas they contain continue to be argued and brought to bear on every aspect of American life. Their concepts remain fresh and pertinent to the latest-breaking news - to events that the Framers could scarcely have imagined.

Related Articles:

NARA Conservators Meet the Challenge Every Day
The Stone Engraving: Icon of the Declaration


Mary Lynn Ritzenthaler, who is chief of the Document Conservation Laboratory, joined the staff of the National Archives and Records Administration in 1985. She worked previously for the Society of American Archivists and the University of Illinois at Chicago and studied bookbinding for many years in Chicago. She has written extensively on archives preservation topics.

Catherine Nicholson is supervisory conservator in the Document Conservation Laboratory. She has an M.S. in Conservation from the University of Delaware/Winterthur Museum program and has worked as a paper conservator at the National Archives and Records Administration since 1984.
Articles published in Prologue do not necessarily represent the views of NARA or of any other agency of the United States Government.

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