Magnesium Revisited

A B S T R AC T

A recent project undertaken at the Library of Congress

(LC) and reported at the AIC conference in Washington in

2003 was interesting in more ways than originally intend-

ed. Inspired by the conference theme of “Tr e a t m e n t

Revisited,” we embarked on a project focused on exami-

nation of objects executed in iron-gall ink and treated with

various deacidification solutions over the years. It is sur-

prisingly uncommon to examine objects treated in the past

as part of our mechanism of evaluation and we wondered

what we might glean from such an exercise. Magnesium

bicarbonate as a deacidification agent has been used at the

Library for decades and its use would seem to have been

challenged by the results of recent research. Additionally,

iron-gall ink has been the subject of intense study in the

past few years. Although a multi-year research project

designed to gather objective data on various treatments

options used in treating iron-gall ink is currently underway

at the Library, we wondered what might be revealed by a

concurrent, more subjective project looki ng at objects

which had undergone deacidification with magnesium

bicarbonate. Acknowledging that the judgments resulting

from visual examinat ion of ob jects treated in the past

would be subjective, it was generally felt that given the

pervasive use of subjective knowledge in our profession,

the exercise had some validity.

While various conclusions and opinions could be

drawn from this exercise, some of the tangential issues that

arose are equally worth noting. A brief history of the evo-

lution of the Library’s standard treatment of objects

executed in iron-gall ink will be articulated. This process

was particularly interesti ng since the exercise led to a

greater appreciation of the procedures that are currently

employed and put them in a context that is not always

The Book and Paper Group Annual 22 (2003) 33

Presented at the Book & Paper Group Session, AIC 31st Annual

Meeting, June 5–10, 2003, Arlington, Virginia. Received for pub-

lication Fall 2003.

apparent if one is unfamiliar with how they were arrived

at. In order to fairly assess our present methods it is nec-

essary to understand their evolution out of decades of

common experiences, exhaustive discussions, and scien-

tific inquiry. The complexity and small size of our field

makes definitive and/or objective data hard to come by and

fuller understanding of any given issue can only be gained

through familiarity with a broad cross-section of the liter-

ature and related practical experience. Secondly, the results

of our examination of the objects previously treated with

magnesium bicarbonate will be presented. Fi n a l l y, some

of the unexpected results that arose during the course of

the study and what they reveal about how we evaluate our

work will be discussed.

H I S T O R Y

The treatment of iron-gall ink has posed complicated

challenges for conservators and conservation scientists.

The variety of iron-containing ink formulas and the dra-

matic impact those formulations can have on properties,

the ink’s self-destructive nature which compels us to “do

something,” and the complexity of its chemistry, making

s c i e n t i fi c research that is applicable to treatment difficult to

design, has left us with an impressive amount of conflict-

ing information. The Library of Congress, with millions of

pages penned in iron-gall ink and a strong mandate for

public access, has been interested and participatory in the

development of appropriate preservation strategies. Three

distinct eras of treatment during the twentieth century can

be defined at the Library.

The first era from 1900 into the 1940s was dominated

by the practice of silking. Throughout this period, thou-

sands of documents were silked every year although

treatment details on individual objects do not exist. The

practice of silking as described by the chief practitioner at

the Library, William Berwick, began with immersion into

a warm water bath to clean the manuscript of grime and

pressing between newspapers to flatten. In a second, sep-

Magnesium Revisited

H O L LY H . K R U E G E R

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A B S T R AC T A recent project undertaken at the Library of Congress (LC) and reported at the AIC conference in Washington in 2003 was interesting in more ways than originally intend- ed. Inspired by the conference theme of “Treatment Revisited,” we embarked on a project focused on exami- nation of objects executed in iron-gall ink and treated with various deacidification solutions over the years. It is sur- prisingly uncommon to examine objects treated in the past as part of our mechanism of evaluation and we wondered what we might glean from such an exercise. Magnesium bicarbonate as a deacidification agent has been used at the Library for decades and its use would seem to have been challenged by the results of recent research. Additionally, iron-gall ink has been the subject of intense study in the past few years. Although a multi-year research project designed to gather objective data on various treatments options used in treating iron-gall ink is currently underway at the Library, we wondered what might be revealed by a concurrent, more subjective project looking at objects which had undergone deacidification with magnesium bicarbonate. Acknowledging that the judgments resulting from visual examination of objects treated in the past would be subjective, it was generally felt that given the pervasive use of subjective knowledge in our profession, the exercise had some validity. While various conclusions and opinions could be drawn from this exercise, some of the tangential issues that arose are equally worth noting. A brief history of the evo- lution of the Library’s standard treatment of objects executed in iron-gall ink will be articulated. This process was particularly interesting since the exercise led to a greater appreciation of the procedures that are currently employed and put them in a context that is not always The Book and Paper Group Annual 22 (2003) 33 Presented at the Book & Paper Group Session, AIC 31st Annual Meeting, June 5 –10, 200 3, Arlington, Virginia. Received for pub- lication Fall 2003. apparent if one is unfamiliar with how they were arrived at. In order to fairly assess our present methods it is nec- essary to understand their evolution out of decades of common experiences, exhaustive discussions, and scien- tific inquiry. The complexity and small size of our field makes definitive and/or objective data hard to come by and fuller understanding of any given issue can only be gained through familiarity with a broad cross-section of the liter- ature and related practical experience. Secondly, the results of our examination of the objects previously treated with magnesium bicarbonate will be presented. Finally, some of the unexpected results that arose during the course of the study and what they reveal about how we evaluate our work will be discussed. H I S T O R Y The treatment of iron-gall ink has posed complicated challenges for conservators and conservation scientists. The variety of iron-containing ink formulas and the dra- matic impact those formulations can have on properties, the ink’s self-destructive nature which compels us to “do something,” and the complexity of its chemistry, making scientific research that is applicable to treatment difficult to design, has left us with an impressive amount of conflict- ing information. The Library of Congress, with millions of pages penned in iron-gall ink and a strong mandate for public access, has been interested and participatory in the development of appropriate preservation strategies. Three distinct eras of treatment during the twentieth century can be defined at the Library. The first era from 1900 into the 1940s was dominated by the practice of silking. Throughout this period, thou- sands of documents were silked every year although treatment details on individual objects do not exist. The practice of silking as described by the chief practitioner at the Library, William Berwick, began with immersion into a warm water bath to clean the manuscript of grime and pressing between newspapers to flatten. In a second, sep-

H O L LY H. K R U E G E R

arate step, both sides of the document were pasted out with cooked flour paste and the silk was placed on top and smoothed out. The object was then placed between two sheets of paraffin paper and pressed to flatten between smooth, white, unglazed pulp board. It is difficult to match the variations in the silking mate- rials and techniques with an object’s condition today as there are no individual records. Paste recipes varied, as did the silk itself in quality and gauge. Silked objects today are in various states of preservation. Silked documents gener- al display a low surface pH, between 3.5 and 4. Some early recipes for the starch paste include alum and some silked items do test positive for alum. Most silked documents have darkened significantly and become brittle. Sometimes the silk itself is in an advanced state of deterioration with the document holding the silk together rather than the other way around! In other cases, although yellowed, stiff, and unnaturally flat, the document remains relatively intact. While the technique represented the best knowl- edge of the day and required considerable skill to execute, the alum and embrittling nature of the silk proved to be its undoing. Additionally, many of the inks reacted badly to the treatment—sinking, smearing, and bleeding—and the paste acted as a poultice, pulling elements of the ink into the paste and silk. The silk texture was impressed into the paper due to the excess pressure exerted. The silk inter- feres with the legibility of the writing, a quality that becomes more noticeable with time as the paste and paper yellow. These factors, along with better understanding of the nature of paper aging and new ideas about how to treat them, led to the decline of silking. The second era of treatment of iron-gall ink documents is dominated by the practice of lamination. Lamination involved sandwiching an artifact between cellulose acetate film and semi-transparent paper and running it though a hot press to melt the layers together. In 1948, the annual report from the Manuscript Division states that over thir- t y-five thousand documents were laminated. The era of mass treatment had arrived at the Library. It is easy to see the managerial appeal of this type of operation. Lamination was seen as far superior to silking and a method that received considerable attention from the leading figures in the manuscript restoration field at the time. Its superiority was demonstrated by its speed, reduced specialization of labor, and cost. The early laminations did not include a deacidification step, and the objects frequently turned brown after the pro- cess. This browning was thought to be a result of accelerated aging due to the tremendous heat involved with the process. The browning phenomena led William Barrow to incorporate a deacidification step. Although he was not the “discoverer” of the role acid plays in paper deterioration, he was unparalleled in disseminating this information through the promotion of his laminating tech- The Book and Paper Group Annual 22 (2003) nique. The first method he recommended was the “Barrow Two-Step” that involved successive twenty-minute baths in concentrated calcium hyroxide, followed by concentrat- ed calcium bicarbonate. This treatment was replaced by the “Barrow One-Step,” immersion into saturated magnesium bicarbonate. The quantity of buffering salts introduced into the papers by these methods is unknown but certainly adverse reactions of iron-gall ink to what is now seen as extremely high pH is something we have all encountered in our work. The high pH of the baths and the resultant high pH of the papers are almost certainly to blame for the familiar changes to iron-gall inks such as reddening, fading, and/or sinking. Despite the managerial appeal of the lami- nating practice, it became increasingly acknowledged that the difficulties associated with this approach outweighed the benefits. Unfavorable reactions of the media to the concentrated deacidification solutions were noted and began to be taken more seriously. The concept of “individ- ual treatment” began to gain stature as conservation took its early steps towards professionalization in the 1950 s and ’60s. The third era in treatment of iron-gall ink began with the establishment of the Conservation Office in 1967 and the appointment of Peter Waters as the first “Restoration Officer” in 19 71. One of his early accomplishments was convincing the Library to halt the practice of lamination. Additionally, deacidification and the treatment of iron-gall ink were issues that received considerable early attention. Many conservators working in the Library at the time reported problems with deacidification in general and aqueous treatment of iron-gall ink, such as sinking and physical breakage of ink-corroded areas. Use of the con- centrated deacidification solutions frequently caused a change in color and/or intensity of the inks and left a grit- ty deposit on the surface of the paper. Mr. Waters formed a deacidification committee of staff conservators and scien- tists. One of the first actions he took as head of the committee was to direct Norvel Jones to conduct a survey of conservators at the Library on practices they used. He hoped to record the various methods employed, define areas of needed research, and establish standard practices within the laboratory. The survey revealed that many con- servators were diluting the deacidification solutions by at least half to alleviate the gritting problem. It was also noted that some did not use magnesium or calcium salts at all in their treatment of iron-gall ink due to experiences with unwanted effects. As a result of the work of the deacidifi- cation committee and Margaret Hey’s research as a visiting scientist at LC studying deacidification and iron-gall ink treatments, Mr. Waters developed and distributed standard guidelines to the staff. These guidelines acknowledge and support individual experience and judgment but direct that if a book or other item is washed, it should be followed by deacidification. Magnesium bicarbonate is mentioned as

degradation of iron-gall ink has been published indicating the role of the iron 2+ compound (FE II) in prompting the oxidation process. This work inspired the development of two decidedly new approaches to treatment. Washing objects in water near the boiling point removes most of the FE II and has been reported to have been used successfully. More promising, perhaps, is a treatment proposed by Han Neevel at ICN (Netherlands Institute for Cultural Heritage) which would sequester any free FE II perma- nently through the use of phytates. Conservators at the Library were both excited by this second approach and alarmed by some of the results that were reported in the study. Neevel’s experimental results included papers d e a c i d i fied with saturated solutions of magnesium bicar- bonate that yellowed significantly upon aging, though effectively protected from acid hydrolysis and oxidation. Yellowing of paper associated with magnesium compounds has been previously reported but is countered by other research, and these conflicting results can often be attribut- ed to the study’s protocols. Studies using concentrated solutions tend to produce negative results and conflicting information is produced by differing aging methods. Neevel used saturated solutions in his experiments and employed a cycling temperature and relative humidity aging protocol. Additionally, the ink recipe employed by Neevel exaggerated the proportion of FE II in historic recipes in order to study the effects of the phytate on high- ly corrosive ink. While acknowledging the limitations of our current practices using magnesium compounds to treat iron-gall ink, in that they do nothing to prevent FE II from continuing to form, we were nevertheless reluctant to abandon our practices and the thirty years of accumulated experience for something that is unproven in practice. As a result, the Library of Congress is currently engaged in a multi-year study aimed at gathering data that would allow us to assess ICN’s work within the context of our current and past practices. Among the changes in experimental protocol adopted are three important ones. Because Library conservators have not used saturated solutions for thirty years, the more diluted solutions are being substituted. In addition, recent- ly adopted ASTM (American Society for Testing and Materials) standards for artificial aging are being used instead of the cycling method. Finally, real ink samples will be tested along with the exaggerated ink formula for com- parison. Early results of the Library’s study tend to support the results obtained by Neevel, but as is typical of studies involving iron-gall ink, raise more questions than they answer. While a full report is still a year or two off, we were inspired by this year’s AIC annual meeting theme of “Treatment Revisited” to perform a parallel study that would look at actual objects treated in the past. The Book and Paper Group Annual 22 (2003) R E S U LT S O F T H E P R O J E C T While well versed in the dangers associated with aque- ous treatment of iron-gall ink, many conservators past and present had been able to perform safely the “standard” Library of Congress treatments previously described. I per- sonally have treated scores of iron-gall ink documents through washing and deacidification with magnesium bicarbonate and felt that with proper pre-testing and con- sideration the problems with ink changes could be avoided. On several occasions there was the opportunity to “test” the treatment on part of the document, compare it with the untreated part, and allow for more confidence in pro- ceeding. The significant body of positive experiences in treating iron-gall ink was difficult to reconcile with the accumulating evidence of possible harm that might result. After all, if paper yellowing or dramatic ink changes were readily apparent, development of the Library’s standard treatment would have developed in a different direction. Perhaps these changes occur only upon aging. To begin our reexamination of treatments performed in the past, all of the treatment, photographic, and some administrative records accumulated since the establishment of the Office were combed, and iron-gall ink objects that were treated with magnesium compounds were noted. The records that had treatment details and photographic information asso- ciated with the treatment that reasonably could be used to make some type of assessment were brought to the lab. All of the conservators were invited to visually examine the objects and discuss their perceptions. Unfortunately, doc- umentation such as colorimetry or spectrophotometry that would provide a mechanism for an objective assessment does not exist. Nevertheless it was decided to proceed with the available information, reasoning that while fallible and notoriously variant, a conservator’s visual perception and aesthetic sense are a valuable part of the preservation disci- pline and will remain so. What was found through this exercise was surprising on a number of levels. The first surprise was that relatively few objects penned in iron-gall ink received aqueous treat- ment in the thirty years since the establishment of the Office. Perhaps the reason for this is that an iron-gall ink document has to pass a gauntlet of tests before it is consid- ered for aqueous treatment and some conservators have felt that treatment with magnesium bicarbonate is too risky to be considered. The second surprising result was that those objects that did pass the various tests and were treat- ed through the standard approach described previously have held up well, mechanically as well as visually. Examination of the available documentation that includes written information, color slides, and color transparencies supported our visual perceptions. Of the several hundred pages examined, we could find no obvious paper color shift associated with the magnesium treatments. Any alteration

to inks that had been noted in the reports were subtle and it was difficult to determine if the inks had actually changed in color or our perception was influenced by the color balance shift in the paper tone. While acknowledging the limitations of this exercise, the results obtained sup- ported the notion that the careful testing and open exchange of information amongst ourselves had been effective in avoiding many of the negative effects associat- ed with aqueous and magnesium bicarbonate treatment of iron-gall ink documents. U N E X P E C T E D R E S U LT S While definitive and objective answers to the questions that prompted this study were not found, some of the tan- gential details revealed warrant discussion. If conservators are to have meaningful discussions about previous treat- ments, the following factors need to be taken into consideration. Conservators remember every excruciating detail of a treatment they judged went wrong but do not remember the ones that went well. While “self-flagellation” is a well- known, and possibly beneficial, character trait of conservators, the weight given to negative experiences was disproportionate to the far more common positive experi- ences. Does this built-in “prejudice” serve us well? Could it, in part, explain the reluctance of conservators today to incorporate deacidification into their practice despite their admission that it is beneficial to the paper? After all, if done correctly, we do not see any change. What we do remem- ber are objects that have behaved badly or reports of others who have had negative experiences. While “negative expe- riences” is obviously an enormously important factor to consider when designing a treatment protocol, is it the only one? Certainly this prejudice impedes the formation of a balanced program as well as colors the sometimes decidedly emotional aspect of our discussions. The notion of “acceptable change” in manuscript con- servation is true in theory only. Much is made of the differing standards between fine art and manuscript con- servation. It was found that among LC conservators past and present that the only acceptable change in the visual appearance of iron-gall ink is “no change.” This concept has driven development of the standard treatment proto- col principle, overriding the desire to address deteriorating components by invasive treatments, and has been in direct c o n flict with information coming from the scientific com- munity about the long-term benefits of treatments that deposit alkaline salts into the paper. We need to find some practical way to incorporate objective standards in our measurements and more fully understand and acknowledge that our visual perceptions are subjective. Conservators are critical and have a highly developed visual sense. This quality is obviously one of

the things that sets us apart from much of the rest of the world and is a vital component in our work. Unfortunately, what any given individual conservator “sees” and makes judgments about can be quite at odds with his or her colleagues. Without objective standards, we are forced to accommodate these differences in our prac- tice. It became obvious during the course of this project that these qualities may be seen as a source of both strength and weakness. The following two examples encountered during this study highlight this point. When looking for objects for this project, several people mentioned one of the Library’s “Top Treasures,” James Madison’s “Notes on the Continental Congress” as an example of a deacidification treatment of iron-gall ink gone awry. There are two volumes; the first had been washed and deacidified. Lab legend had it that the inks had changed so dramatically in response to the magnesium bicarbonate deacidification that the treatment was halted halfway. In fact, it was generally felt that one could tell just where treatment had stopped by looking through the papers. We started by looking at the volume that had been treated. We immediately began ascribing qualities that we normally associate with washing and deacidification such as blurred, reddened, and sinking inks. Then we turned to the volume that had not been treated. To our surprise, the inks looked very similar. There were inks that were blurred and some that were just as reddened in the untreated volume as there were in the treated one. In short, the range of ink appearance in the treated volume looked very similar to the ink appearance in the volumes that had not been treated. There were no details about the treatments other than that the papers were “washed and buffered.” Very curious about exactly what had been done during the treatment, we had the volumes tested by scan- ning electron microscope (SEM) analysis. The manuscripts had indeed been washed, displaying the typ- ical spectra of water-washed objects. To our complete surprise, however, no magnesium or other alkaline salt could be detected by this method. Although the results are not definitive—more research would have to be per- formed to clear the mystery of exactly how the first volume of the treasure was treated—it is most interesting to note the mythology that had surrounded this object and the weight given to this “myth” when conservators were considering treatment options for other objects. The second example illustrating the difficulty conser- vators encounter when assessing their work may be found with Heather Wanser’s research. In this study, one expend- able iron-gall ink document was cut up and each piece subjected to various alcohol-modified washing and mag- nesium bicarbonate deacidification treatments. Twelve senior conservators were then asked to visually evaluate the results. The judgments of the highly-trained, visually- Krueger Magnesium Reconsidered

aqueous treatment of paper objects: State of the art. Restaurator 20: 167–180. Reissland, Birgit, and Suzan de Groot. 1999. Ink corro- sion: Comparison of currently used aqueous treatments for paper objects. In IADA preprints, 9th IADA Congress, Copenhagen, August 1 6–21, 1999 , 121 – 13 0. Copenhagen: Royal Academy of Fine Arts, School of Conservation. Schierholz, O. J. 1936. Process for chemical stabilization of paper and paper products. U.S. patent 2,033,452. Shahani, C. 1995. Accelerated aging of paper: Can it real- ly foretell the permanence of paper? Pr e s e r v a t i o n Research and Testing, series 9503_._ Washington DC: Preservation Directorate, Library of Congress. Tang, Lucia. 1981. Washing and deacidifying paper in the same operation. In Preservation of paper and textiles of his- toric and artistic value II. Advances in Chemistry Series, no. 193 , ed. John C. Williams, 63 – 86. Washington, D.C.: American Chemical Society. Wanser, Heather. 1986. An evaluation of standard and m o d i fied aqueous deacidification treatments of antique iron gall ink samples. In Abstracts of papers presented at American Institute for Conservation, 24 th annual meeting, Norfolk, Virginia, 47. Washington, D.C.: American Institute for Conservation. Wilson, William K., Ruth A. Golding, R. H. McClaren, and James L. Gear. 1981. The effect of magnesium bicarbonate solutions on various papers. In Preservation of paper and textiles of historic and artistic value II. Advances in Chemistry Series, no. 193 , ed. John C. Wi l l i a m s , 87 – 107. Washington, D.C.: American Chemical Society. Unpublished Works Hengemihle, Frank. 2000. A comparison of treatments with aqueous magnesium bicarbonate. Research and Testing Division, Library of Congress. Jones, Norvell. 1976. Memorandum to Peter Waters with results of survey of deacidification methods used at the Library of Congress. Administrative records, Conservation Division, Library of Congress. Waters, Peter. 1977. Purpose of the committee and the establishment of deacidification standards. Memorandum to Norvell Jones, Chairperson of Restoration Office Deacidification Committee. Written 18 February 1977. Conservation Division, Library of Congress. H O L LY KRUEGER Senior Paper Conservator Library of Congress Washington, D.C. [email protected] Krueger Magnesium Reconsidered 39

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Magnesium Revisited

H O L LY H. K R U E G E R