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IR 056 136
Porck, Henk J.
Mass Deacidification: An Update on Possibilities andLimitations.
Commission on Preservation and Access, Washington,
DC.

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Archives; Chemical Reactions; History; Libraries;*Library Collections; Library Policy; *Paper(Material); *Preservation; Printed Materials;
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Barriers to Implementation; *Paper Deacidification

ABSTRACTThis report provides an update of the possibilities
and limitations of currently available mass deacidification methods,
focusing on the major developments in research and application of themain operational systems. This study is intended primarily to support
the development of a well-considered preservation policy bylibrarians and archivists, with a focus on the practical implicationsof mass deacidification rather than the technical details of thedeacidification process. The study provides a brief history of thedevelopment of the technical process, a condensed description of thetreatment principle, an overview of available research and test
results, indicating the main advantages and disadvantages of theprocess, and an inventory of actual applications for five massdeacidification systems: (1) "Battelle"; (2) "Bookkeeper"; (3) "DEZ";(4) "FMC"; and (5) "Wei T'o." Several other initiatives are also
described, involving large-scale rather than mass treatment
technologies, and essentially combining deacidification withstrengthening of paper. The main findings are discussed within theframework of a critical evaluation of the current possibilities andlimitations of mass deacidification in general. A list of contacts isprovided. (Contains 86 references.) (Author/SWC)**************************************AA:ck*****************************

Reproductions supplied by EDRS are the best that can be madefrom the original document.
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he Commission on

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Mass Deaddifficafion
An 1:pdate on
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Mass Deacidification
An Update on
Possibilities and Limitations

Henk J. Porck
Department of Library Research
Koninklijke Biblioheek/
National Library of the Netherlands
The Hague

European Commission on Preservation and Access,
Amsterdam
Commission on Preservation and AccessWashington

October 1996

The European Commission on Preservation and Accessgratefully acknowledges the financial support of the following
institutions and organizations

Die Deutsche Bibliothek, the National Library of Germany
Koninklijke Bibliotheek, the National Library of the Netherlands
Marianne and Marcus Wallenberg Foundation

Ministry of Education, Culture and Science of the Netherlands
National Archives of Denmark
National Archives of Ireland

National Archives of Norway
National Library of Ireland
National Library of Poland
National and University Library of Iceland
National and University Library of the Republic of Slovenia
Royal Netherlands Academy of Arts and Sciences
Swiss Federal Archives

5

Wenn ein Papier abhanden kommt
Auf das man geschrieben hat
Das ist nicht schlimm.
Vielleicht namlich liest es einer
Und verandert sich.
Schlimm ist nur
Wenn das Papier zerfallt.

Benoit Brecht(Gedichte 1933-1938)

6

Acknowledgments
The author would like to express his appreciation to his colleagues of
the Koninklijke Bibliotheek in The Hague: Wim Smit (Conservation& Optical Technology) for direct assistance and useful suggestions,
Clemens de Wolf (Collections & Research) and Hans Jansen (Library
Research) for their guidance. Yola de Lusenet (European Commission

on Preservation and Access, Amsterdam) is acknowledged for her
great support. It is due to the willingness of the various contacts listed

at the end of the report, to offer personal opinions and expert
knowledge that important information on the current status of thedifferent deacidification systems could be included. Don Sebera(preservation consultant, Washington D.C.) and Astrid Brandt (scientific advisor, Bibliotheque Nationale de France, Paris) offered constructive comments on the original draft of this publication.
Reactions on this report can be sent to the following address:

Dr. H.J. Porck
Conservation scientist
Department of Library Research
Koninklijke Bibliotheek,
National Library of the Netherlands
P.O. Box 90407
2509 LK The Hague
The Netherlands

7

Table of contents
Acknowledgments 4

Summary 7

Introduction 8
Battelle

11

Bookkeeper 16

DEZ 22
FMC 29
Wei T'o 33
Other initiatives 38

Evaluation 42
References 46

List of contacts 53

8

Summary
This report is the result of a desk research project aiming to provide
an update of the possibilities and limitations of currently available
mass deacidification methods. It focuses on the major developments
in research and application of the main operational systems.
The Introduction outlines the aims and design of the present study,

developed in consultation with the European Commission on
Preservation and Access.

The next chapters describe the mass deacidification systems
included in this study: Battelle, Bookkeeper, DEZ, FMC, and Wei To.
For each system a brief history of the development of the technicalprocess is presented, as well as a condensed description of thetreatment principle, an overview of available research and test results,

indicating the main advantages and disadvantages of the processconcerned, and finally an inventory of actual applications of thesystem.

In addition several other initiatives are described, involving largescale rather than mass treatment technologies and essentially combin-

ing deacidification with strengthening of paper. These initiatives
include the Biickeburg process, the Graft-copolymerization process, thepaper splitting process and the Vienna process.

The data compiled in this report do not allow any conclusions inthe sense of a recommendation in favor of any of the techniques
described. Instead, in a final section some of the main findings are
discussed within the framework of a critical evaluation of the current
possibilities and limitations of mass deacidification in general.
The References list the literature consulted for this study, publications as well as internal reports. Finally, the List of contacts gives thenames of representatives of firms and institutions who offered relevant

information about the present state of affairs and/or shared theiropinions on relevant issues.

7

Introduction
Aims and set-up
On the basis of a request of the Commission on Preservation andAccess (CPA) in July 1995, the Koninklijke Bibliotheek, the National
Library of the Netherlands, offered to provide an objective overview
of the status of mass deacidification, addressing the major developments. In consultation with the CPA and the European Commission
on Preservation and Access (ECPA), the aims and set-up of the study
were defined in more detail.
The primary goal was to present a current and essentially worldwide overview of the possibilities and limitations of the use of massdeacidification methods. Intended primarily to support the develop-

ment of a well-considered preservation policy by librarians andarchivists, the study was confined to those mass deacidification
systems which have already reached the stage of exploitation, i.e. theBattelle, Bookkeeper, DEZ, FMC, and Wei T'o processes.

Although aqueous deacidification and other conservation techniques can be scaled up considerably, e.g. by moving belt and othermechanical principles (Brinkhus 1988), these methods are in principle
excluded from the present study, as are mechanized but principally
single-sheet nonaqueous deacidification techniques. An exception wasmade for those large-scale processes which combine both paper deacidification and paper strengthening as these processes clearly offer an

additional benefit for paper that is already weakened and/or brittle,
in contrast with the other mass deacidification systems which, aside
from the FMC method, only work preventively by slowing down
further degradation. The initiatives worth mentioning include the
Biickeburg, graft-copolymerization, paper splitting and Vienna processes.

In reviewing the methods, focus is on the practical implications ofmass deacidification rather than on technical details of the deacidification process. In particular, the results of test research into the positive
and negative effects of the deacidification will be considered. In thisrespect, the experiences of library and archival institutions in theactual application of mass deacidification in practice are thoroughly
addressed.

For each of the main mass deacidification methods sections areincluded covering (i) the historical development of the process
technique, (ii) the procedure and chemical principles of the treatment,(iii) the results of investigations into process efficiency and effectiveness, and (iv) the application of the process in the practice of library

and archival institutions. The latter section includes information, if

available, on health and safety risks, cost estimates, and, for thedifferent institutions involved, quantitative data on the extent andfrequency of treatment, priority and selection criteria, overall
evaluation of the treated materials, and future planning.

Mass deacidification

As the optimization of mass deacidification systems represents acontinuing process of research efforts and subsequent changes in thetreatment ingredients and procedures, data in this report are presented
in chronological order. For the sake of objectivity, the mass systems
discussed are arranged alphabetically. It should be stressed that thisreview is not intended as a comparative investigation leading torecommendations in favor of one or another of the systems. The lastpart of the report is devoted to a critical evaluation of the informationcollected for this overview.
The present study was set up as a desk-research project, for which

various literature sources, such as articles, internal reports andpublished statements, were used. Both for the purpose of a criticalevaluation of the data and to acquire information on the most recent
developments, representatives of the different firms and institutions
were contacted. By consent their personal communications have been

incorporated in the text and their names included in the list ofcontacts, at the end of this report. To obtain data for a world-wide

overview, a general request for information was also sent out.
Although negative answers i.e. no mass deacidification activities are
currently being undertaken have not been included in the text, therespective respondents are mentioned in the list of contacts.

The closing date for the gathering of information for this report
was June 15, 1996.

Retrospective view
One of the first applications of paper deacidification is described by
O.J. Schierholtz (1936) in his patent for the conservation of wallpaper,using aqueous solutions of calcium bicarbonate. In 1943 W.J. Barrowdeveloped a technique for lamination of paper with cellulose acetate,
combined with the deacidification of the paper with aqueous solutionsof calcium or magnesium carbonate (Barrow 1965).
Presently, aqueous deacidification is essentially confined to manualconservation treatment. A more or less mechanized variant is themethod developed by 0. Wachter for the Austrian National Library,in which bookblocks are impregnated with aqueous solutions of deacidification and paper-strengthening agents, followed by freezing andfreeze drying of the treated blocks (Wachter 1987a). Another, more
extensively mechanized aqueous procedure is the paper splitting process, developed by W. Wachter at the Deutsche Biicherei (Leipzig). In
this method sheets of paper are split into two layers and strengthened
by insertion of a new central layer of thin paper, containing among
other ingredients calcium carbonate as deacidification agent.
An important disadvantage of aqueous treatment is the solubilityof certain pigments and adhesives used in books and other documents.

-9-11

Henk J. Porck

Also the often prolonged drying which is necessary after treatment
presents a serious problem in the development of large-scale applications. Pioneering work in addressing this problem was done in the
1960s by R.D. Smith, who developed a nonaqueous deacidification
technique based on magnesium methoxide, solubilized in a mixture ofmethanol and freon compounds, which was applied to paper by spraying (Smith 1970). The use of organic solvents, which can easily beremoved by evaporation, has proved to be a sound basis for thefurther development of mass deacidification techniques such as theBattelle, Bookkeeper, FMC, and Wei T'o processes, which are described in this report in more detail.
Another alternative for aqueous deacidification was the use of
gaseous deacidification agents. An early example was the applicationof the vapor of ammonia for book deacidification in the 1950s in
Bavaria, Germany (Smith 1988). The use of cyclohexylamine carbonate (clic), a volatile organic amine, was developed by W.H. Langwell(1966) for the 'Interleaf Vapor Phase Deacidification' (vPD) process.
Another volatile amine, morpholine, has also been investigated for its
use in gaseous deacidification and subjected to a limited mass trial.
The use of a combination of ammonia and ethylene oxide for largescale gaseous deacidification has been developed by Book Preservation
Associates in cooperation with Information Conservation, Inc. (Cunha

1989, Brandt 1992). Unfortunately all these gaseous deacidification
agents pose serious health and environmental hazards.
An important breakthrough in gaseous deacidification, enabling
application on a real mass scale, was the development of the diethylzinc (DEZ) process. The DEZ mass deacidification technique, developed by the Library of Congress in the beginning of the 1970s, will
be discussed in detail in this report.
The last decade has seen an abundance of published and unpublished research reports and specialist literature on the subject of massdeacidification, including several useful reports and reviews (Cunha
1989, Hon 1989, Schwerdt 1989, Sparks 1990, Neevel 1991, Brandt
1992, Harvey 1993, Mann 1994). In addition, media coverage on thepreservation of library and archival materials as a rule emphasizes theimportant role of mass deacidification in addressing this problem, reflecting a growing interest in the subject on the part of the generalpublic.

-10-12

Battelle
Development
By order of Die Deutsche Bibliothek (German National Library,Frankfurt/Leipzig), and supported by a grant of DM 17.5 million fromthe German Bundesministerium fur Forschung and Technologie,
Battelle Ingenieurtechnik GmbH has since 1987 been investigating
different deacidification methods to develop the most suitable system.
The first approach, put in operation in a pilot plant in Frankfurt, wasa process based on the liquid-phase Wei T'o system, using magnesium
methyl carbonate (mmc) as deacidification agent and freon solvents.

Though the treatment procedure is similar to that of the Wei T'osystem discussed below, several improvements had been realized by
the end of 1990, including optimized recycling, fast and homogeneous
drying by means of microwaves, and automatization of the processcontrol (Schwerdt 1989).
A change in the solvent and, as a consequence, in the effective deacidification agent, was necessitated by the stricter environmental
regulations for the ozone-depleting freon compounds, as laid down in
the 1987 Montreal Protocol (Gesetz 1988, Montrealer 1988). The
solvent was replaced by hexadimethyl disiloxane (Wittekind 1994a),. a colorless organic silicon compound which according to Battelle is

not harmful to health and environment. However, hexadimethyl
disiloxane is highly flammable. MMC has been replaced by magnesium
titanium ethoxide (METE) as effective deacidification agent. METE isa combination of magnesium ethoxide and titanium ethoxide, andaccording to Battelle capable of both deacidifying and strengtheningof paper. Finally a compound was added to diminish the surface

tension of the deacidification solution, in order to improve theimpregnation in paper. The Battelle pilot plant, constructed in Frankfurt, was moved to the Deutsche Biicherei (Leipzig) and put into operation in 1994.

By using microwave heating equipment, combined with aningenious control of the radiation process, the drying step could beshortened to approximately 2 hours (Behrens 1993). However, in thecourse of time, test results showed that the microwave procedure
posed many technical and practical problems. For instance, local heatdamage of paper caused by metal staples and wire stitches presented
a serious problem as these stitches are not uncommon, and especiallyfrequent in German books from the 19th and early 20th century.

Consequently, Battelle Ingenieurtechnik decided to replace themicrowave equipment by a conventional drying technique, using
reduced pressure and heat. This modified installation is currently
being constructed in Eschborn, the new location of Battelle since
1993.

-11-

13

Henk J. Porck

Treatment principle
Type of process

Battelle/liquid-phase

Effective agent

Magnesium titanium ethoxide (METE): Mg(0C2H5)2 and Ti(OC2H 4

Solvent

Hexadimethyl disiloxane (HIVIDO;(CH,),SiOSi(CH,),)

Procedure

The current deacidification procedure consists of 4 steps:(i) Predrying: the paper to be treated is dried for 2 days in vacuum at 60°C, inorder to decrease the water content from approximately 6% to 0.5%; the materials
are placed in special boxes.
(ii) Impregnation: the deacidification solution penetrates easily in the paper, and theimpregnation and deacidification are completed in only a few minutes; subsequently the deacidification solution is drained.
(iii) Afterdrying: the remaining deacidification solution in the paper is removed asin the predrying step, by means of vacuum and heat.
(iv) Reconditioning: after completion of the drying, the documents are reconditioned for 3 weeks in order to regain normal water content in the paper; thestorage room is well ventilated in order to diminish the odor of the treatedmaterials. Formerly both drying steps were performed by means of microwaves.

Initial reactions

Magnesium ethoxide and titanium ethoxide hydrolyse easily in the presence ofwater in the paper. In first instance a metal hydroxide is formed:
Mg(0C2H5)2 + 2 H2O -> Mg(OH)2 + 2 C2H5OH,

Ti (0C2H) 4 + 4 H2O --> Ti(OH)4 + 4 C2H5OH

The forming of ethanol (C2H5OH) is probably the cause of the typical (sweet)
odor of the treated paper. Under influence of the environmental air, a second
reaction step will form magnesium carbonate (MgCO3) and titanium dioxide(Ti02).
Deacidification

The magnesium carbonate and the residual metal hydroxides neutralize the acids
present in the paper.

Alkaline reserve

The excess of magnesium carbonate in the paper forms the alkaline reserve, protecting the paper against future acidification.

Research results
The first thorough and independent scientific studies of the Battelle
process have been performed in the Netherlands. In 1994 the CNC,
the National Preservation Office of the Netherlands, reported theresults of a pilot study on the effects of the Battelle deacidification
method, which indicated a number of advantages and disadvantages(Pauk 1994). The CNC decided to do a more elaborate study on theBattelle method, which was carried out by TNO Center for Paper &Board Research in Delft and the Koninklijke Bibliotheek in The
Hague (Deventer 1995, Pauk 1995, Havermans 1996).

The primary aim of the investigations was to obtain a thoroughinsight into the positive and negative effects of the Battelle deacidification method on books and archival materials. Important aspects were

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14

Mass deacidification

the directly observable effects of the treatment, the homogeneity ofthe deacidification, and the effect on the permanence of the paper. For
permanence, both chemical and physico-mechanical paper characteristics were examined; not only the effects of accelerated (thermal) ageing
were investigated, but also the protection offered by the deacidifica-tion treatment against the air pollutants sulfur dioxide and nitrogendioxide.

In general, the Battelle deacidification appeared to result in apositive contribution to the permanence of the paper, both in books
and in archival materials. In 84% of the books, and 2 out of 3 archival
materials, paper degradation was convincingly inhibited in the longterm, and there were clear indications that the Battelle treatment
protects against the influence of acid air pollutants.
Despite these positive results it was concluded from the research

results that the Battelle process suffers from a number of shortcomings which could obstruct a large-scale application. In the firstplace a large part of the testmaterial (40% of the books and 2 out of
3 archival materials) showed a significant immediate decrease in paper
strength as a direct result of the deacidification treatment. Moreover,
the ageing tests showed that also in the long term a considerable partof the tested books (16%) and archival materials (1 out of 3) do notbenefit from the Battelle treatment. Secondly, despite the introduced
improvements in the treatment procedure, there were still undesiredside effects in the deacidified materials, such as discolorations, white

deposit, Newton rings, bleeding of inks and dyes, odor and thedifferent 'feel' of the paper. Finally there was no homogeneous
distribution of the deacidification agent in books and compact stacks
of paper.
There were indications that certain properties of paper, such as
porosity and nature of sizing may have an influence upon the effect(positive or negative/no effect) of the Battelle treatment on paper
permanence. Further investigation of these paper characteristics isrecommended in the research report, also in order to come to adefinition of inevitable preselection steps for the Battelle system.
The results of the CNC investigations, as summarized here, are incontradiction with the claims put forward by Battelle on the basis of
their own test results (Wittekind 1994a, 1994b). Both the alleged
general strengthening, as a direct result of the treatment, and theabsence of undesirable side effects appear to be disproved. However,
the materials tested in the CNC investigation were treated by Battellein the summer of 1994, and Battelle has stressed that since thenadditional improvements have been introduced in the treatment
procedure, especially in the drying steps, resulting in the further
reduction of side effects and improved homogeneity of the deacidification (Wenzel, pers. comm. 1996).

13 15

Henk J. Porck

Last year the modified process was tested by several German
libraries and archives. Of the institutions involved, the following
responded to a request for information: the Landesarchiv in Berlin(Dettmer, pers. comm. 1996), the Staatsbibliothek zu Berlin (Baron,
pers. comm. 1996), the Bibliothek fur Bildungsgeschichtliche For-

schung in Berlin (Bierwagen, pers. comm. 1996), the Deutsches
Museum in Munchen (Berninger, pers. comm. 1996), the Bayerische

Staatsbibliothek in Miinchen (Trapp, pers. comm. 1996), theBundesarbeitsgericht in Kassel (Welle, pers. comm. 1996), the MaxPlanck-Institut fur Europaische Rechtsgeschichte in Frankfurt (Deter,pers. comm. 1996), the Universitatsbibliothek in Mannheim (Leichert,
pers. comm. 1996), the Hessisches Staatsarchiv in Darmstadt (Wolf,
pers. comm. 1996), the Hessisches Landes- and Hochschulbibliothek
in Darmstadt (Staub, pers. comm. 1996) and the Landesbibliothek in
Coburg (Erdmann, pers. comm. 1996). Although the investigations are
not yet fully completed, the first results of the performed test runs are
generally considered encouraging.
Over the last few years the Battelle system has also been tested in

Switzerland by the Landesbibliothek (National Library) and theBundesarchiv (Federal Archives), in cooperation with the Wimmis
Pulverfabrik. The results of the tests with regard to the effectivenessof the deacidification and to the occurrence of side effects werepromising and met the minimal requirements established in July 1995
(Herren 1994, Herren 1995, Herion, pers. comm. 1996).

Application
The first Battelle installation, put into operation in a library setting,
was installed in 1994 in the Deutsche BUcherei (Leipzig). It has been
estimated that the number of books to be deacidified in Die Deutsche
Bibliothek (German National Library, Frankfurt/Leipzig) is aroundto 12 million (Lehmann 1992). Although the Battelle installation isintended to deacidify 400,000 books per year, the actual treatment has
until January 1996 been limited to approximately 60,000 books, andthe system is not yet operating on a continuous basis. Together withtechnicians from Battelle, work is still in progress to adjust andoptimize the treatment procedure. A special problem is the predryingof the books, for which originally microwave equipment has been
installed, creating the technical and practical difficulties alreadymentioned above (Wachter, pers. comm. 1996).
A Battelle installation at present under construction in Eschborn
has been set up as a service center for German libraries and archives
and will initially have a capacity of 120,000 books per year. The
treatment costs will depend on the size and weight of the books, andon the magnitude of the contract with Battelle. For octavo-format

1416

Mass deacidification

books with an average weight of 0.5 kg, costs per book are estimatedat DM 15-20, including transport and insurance. The materials to betreated should be packed by the customers themselves in special boxesof metal wire. The sealed boxes are transported to Eschborn fortreatment, during which the books remain in the boxes. After thetreatment the boxes will be returned. The Battelle center in Eschborn
is planning to extend its services to include freeze-drying of waterdamaged materials and treatment of biological damage by insects andfungi. Plans to found additional Battelle service centers in Germany
are still in a preliminary stage (Behrens, pers. comm. 1996).
Worth mentioning is the initiative of the Landesbibliothek(National Library) and the Bundesarchiv (Federal Archives) in Switzerland to establish a Battelle installation for the deacidification ofbooks and archival materials. On the basis of a survey performed on
mass deacidification systems and of comparative testing of the DEZ
and FMC processes, it was concluded that the Battelle system offers

the best prospects. After a one-year detailed engineering phase,starting in May 1996, plans and cost estimates for the Battelle plant
will be submitted to the Swiss Parliament in 1997. Construction isplanned for the beginning of 1998, and the plant should be operational at the end of that year (Herion, pers. comm. 1996).

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17

Bookkeeper
Development
The Bookkeeper process was developed in the early 1980s by Richard

Spatz, at that time co-worker of Koppers Company Laboratories.
When this company cancelled further investigation into the process
in 1987, because commercial prospects did not seem promising, Spatz
founded a new firm, Preservation Technologies, Inc., and continued
the project under the name 'Bookkeeper'. Initially the pilot plant was
located in Orville, OH, later in Glenshaw, PA, and since September
1995 in Cranberry, PA. Recently the Dutch company Archimascon(Rotterdam) opened negotiations with Preservation Technologies, Inc.,

to construct a Bookkeeper plant in the Netherlands (Dorsten, pers.
comm. 1996).

The deacidification is based on a liquid-phase process using
magnesium oxide (MgO) particles suspended in an organic solvent(perfluoro heptane). In the ongoing process of optimization, the mostrecent adaptation was made at the end of 1995 when, on the basis oftests performed in cooperation with the Library of Congress, byimproving the fluid dynamics of the treatment process, the concentra-tion of magnesium oxide in the suspension could be decreased by
50%, at the same time maintaining a sufficient alkaline reserve. The
lower concentration of magnesium oxide appears to reduce theproblem of white deposits on the treated paper and covers. Modification of the fluid dynamics and additional reduction of the magnesiumoxide particle size also resulted in an improved uniformity of thetreatment (Gaydos, pers. comm. 1996, Report 1996).

Research results
The results of the first investigations into the effectiveness of the
Bookkeeper system were very promising (Cunha 1989). The pH
values of the paper in a series of books, amounting to 4.3-7.5 prior totreatment, could be increased to 7.6-9.0 by the Bookkeeper deacidification. Accelerated ageing tests and folding endurance measurements

showed a significant decrease in the rate of paper degradation as aresult of the treatment. Standard treatment of approximately 1,000
books over a period of 2 years did not reveal harmful effects on inks
and various bookbinding materials, including leather bindings. The
evident absence of damaging side effects is connected with the factthat the treatment suspension is free of alcoholic compounds and that
predrying is not required.
A Belgian study comparing different mass deacidification techniques recommended the Bookkeeper system as one of the best withrespect to the homogeneity of distribution and final values of both
pH and alkaline reserve, and the occurrence of side effects on writing
and printing inks (Lienardy 1992, 1994).

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18

Mass deacidification

Treatment principle
Type of process

Bookkeeper/liquid-phase

Effective agent

Magnesium oxide (MgO)

Solvent

Perfluoro heptane

Procedure

Basically there are two procedures. The Bookkeeper I and II deacidification units
were developed for the deacidification of loose sheets of paper and books withexceptional dimensions. Bookkeeper iii is constructed for the treatment of books ingeneral. All systems are essentially closed circuits and apply mechanical means to
produce controlled motion of the treated objects in the deacidification suspension.
Through this motion, horizontal in the case of Bookkeeper I and II and verticalwith Bookkeeper iii, the books or paper stacks fan open, allowing optimal contactof each individual sheet of paper with the treatment suspension. For this purpose
special holders have been developed, unto which the books are attached by meansof a strong but soft cord, which runs through the gutter region in the middle ofthe books and fixes the spine to the center of the book holder.
Bookkeeper iii consists of 4 cylindrical treatment vessels which are operated insequence and offer a complete treatment of 32 books in 2 hours. The treatment
procedure consists of the following steps:(i) Pretreatment: the books to be treated are placed in the vertical cylinder where,
after a vacuum pretreating step, pressures are equalized and the deacidificationsuspension is pumped in.
(ii) Impregnation: the books are gently agitated parallel to the spine of the books
for 15-20 minutes in the suspension, after which the suspension is drained andrecycled.

(iii) Aftertreatment: the books are dried for 90 minutes under vacuum, and aresubsequently removed from the cylinder to an open room environment for 24hours, to ensure moisture equilibrium.
Deacidification

The magnesium oxide which is introduced by the treatment adheres to the paper
fibers and neutralizes the acids in the paper. In the case of sulfuric acid, thereaction is as follows:

MgO + H,SO4 - MgSO4 + H2O
Alkaline reserve

The magnesium oxide particles which have not reacted form the alkaline reserve inthe treated paper.

In the fall of 1994 a Technical Evaluation Team reported theresults of an extensive investigation of the Bookkeeper process
performed by order of the Library of Congress as second phase of its
1992 Action Plan. It was concluded that the Bookkeeper system has
the potential of meeting the requirements set by the Library for anadequate process. The disadvantages related to heavily coated paper,on which a white deposit was found, and thick books, showing
insufficient alkaline reserve in the inner (gutter) margins (Buchanan1994).

A limited study of the Koninklijke Bibliotheek (National Libraryof the Netherlands) on a series of books treated with the Bookkeeper
process in the summer of 1995 yielded satisfactory results. Accelerated

Henk J. Porck

ageing tests and paper strength measurements showed that of 80% of
the treated books the useful life was significantly increased. Disadvantageous side effects with respect to synthetic bookbinding materials,
odor and discolorations were not observed. The only problem consisted of a white powdery deposit on the paper and covers, especiallywith coated paper (Pauk 1996).
In 1995 the Library of Congress and Preservation Technologies,
Inc. established a joint initiative to improve the Bookkeeper process.
By studying the effects of a wide variety of process modifications on

a series of disposable test books, significant adjustments could be
introduced at the end of 1995, resulting in improved deacidificationof the inner margins of book pages and in the minimizing of powdery
deposits on book covers and (coated) paper. It was concluded fromthe test results that the modified Bookkeeper process met the
Library's requirement for extending the useful life of books by aminimum of 300% and exceeds the 1.5% alkaline reserve requirement.
Moreover, undesirable side effects, such as odor and damage to covers

and adhesives, appeared to be absent. The only problem recognized
was the incomplete impregnation of heavily coated paper (Report1996).

Application
As the safety and health risks are minimal, the Bookkeeper system
could easily be located in a library or archive building. Moreover, theinstallation requires little space, has simple process control and does
not need highly qualified personnel.
Just like the former pilot plant in Glenshaw, the new, enlarged
facility in Cranberry offers the Bookkeeper mass deacidification
services at a commercial scale. The Bookkeeper II installation foroversized books has a capacity of approximately 40,000 books per
year. The Bookkeeper III installation for regular books has a capacityof 120,000 books per year, the treatment costs amounting to $ 11.75
per book, exclusive of transport (Burd, pers. comm. 1996).
Several US libraries have signed up for the Bookkeeper treatment
and offered the following useful information on their experiences.
Unless stated otherwise, the items selected for treatment are (heavily)
used, acidic but not-yet-brittle books, whereas excluded from treatment are pre-1850 and rare books, documents with many illustrations
and/or coated papers and weak bindings, which would not withstandthe stress of the treatment. There appears to be a consensus about theresults of the treatment, which are considered satisfactory on the basisof measurement of pH and alkaline reserve. Undesirable side effects
are generally limited to a powdery deposit on some of the covers andcoated papers.

Mass deacidification

The Case Western University Library (Cleveland) began its use of
the Bookkeeper treatment in 1987 and started regular shipments in1991. To date, approximately 650 books from the general circulating(used) collections have been treated. The library intends to continue
to deacidify yearly shipments of books, up to 1,000 a year (Gubkin,pers. comm. 1996).

The Love Library of the University of Nebraska-Lincoln sent a
shipment of 350 bound volumes from the 19th and 20th century
general collection to Preservation Technologies in 1993. No specificcriteria were used for preselection or for exclusion from treatment.

Though no further shipments have been sent to Preservation
Technologies so far, this will be done again in the future, dependingon the budget, as there is clearly confidence in the Bookkeeper system(Walter, pers. comm. 1996).
The University of Notre Dame has been using the mass deacidifica-tion services of Preservation Technologies, Inc. since 1993, andapproximately 800 volumes (music scores, avant-garde British playwrights printed on cheap paper, and select portions of theology) havebeen treated so far. The University is presently in the process ofnegotiating terms of purchase or lease of Bookkeeper treatment equipment, to be installed in its new laboratory, which it plans to use not
only for its own collections, but also as a deacidification service site
(Jordan, pers. comm. 1996).
Since October 1994, 4,600 volumes from the Northwestern Univer-sity Library (Evanston) have been treated with Bookkeeper. At
present 450 items are being processed per month. Future plans are tocontinue with the Bookkeeper treatment and gradually increase themonthly shipments (Frieder, pers. comm. 1996).
The Cleveland Public Library started using Bookkeeper for maps
and other single sheets of paper in 1994. In 1995 shipment of books
was started, and so far 200 books have been treated. Future plans areto continue the current practice with the Bookkeeper service, but not

on a real mass scale, and to set up an inhouse spray system using
Bookkeeper reagents, primarily for the treatment of large-sized maps
and other single sheets (Olszewski, pers. comm. 1996).

After unsatisfactory results of a project with the Committee on
Institutional Cooperation (cic) on the DEZ and FMC processes in
1991, and more encouraging results of two test runs with Bookkeeper
in 1992, the Pennsylvania State University Libraries contracted withPreservation Technologies, Inc. in 1995; 163 books have been treatedso far. Current plans are to continue with Bookkeeper, but due tofinancial restrictions the number of books that will be sent fortreatment yearly will be limited (Kellerman, pers. comm. 1996).
The Oberlin College Library started to use Bookkeeper in 1995,
and so far 4,700 books have been treated. Besides the white dusting on

19

21

Henk J. Porck

some of the book covers and pages, 20% of the books appeared to be
insufficiently deacidified in the gutter, and a few covers were damaged(bubbling, tackiness). The Oberlin College Library will continue tomass deacidify books in the future, as long as funds are available(Schoonmaker, pers. comm. 1996).
Since 1995 the Pittsburgh Theological Seminary Library has had

approximately 400 books and archival records treated with Bookkeeper. The material consisted of various documents, pertinent to thehistorical background of the institution. Aside from pre-1850 books,
no other materials were eliminated from treatment. Because of thesatisfactory results, unique archival materials have also been processed.
Negative effects were limited to a slight stickiness of some synthetic

bindings. The library has raised an endowment fund and plans tospend approximately $ 8,000 per year on Bookkeeper treatments(Crocco, pers. comm. 1996).
In June 1995 the Library of Congress entered into a trial contract

with Preservation Technologies, Inc. to further optimize the procedure and to treat 72,000 books over a two-year period. The contract
was awarded under the terms of the Library's second Mass Conserva-

tion Action Plan (1995-1997), approved by the US Congress. The
new, expanded facility of Preservation Technologies, Inc. in Cranberry met a number of the Library's contract objectives relating tosecurity, insurance and improved environmental conditions. Up to
January 1996, disposable books were treated and tested as part of a
joint research plan of the Library and Preservation Technologies. On
the basis of the test results, described above, a number of additional

modifications were introduced in the treatment. The resulting
improvement of the deacidification of the inner margins of bookpages strengthened the Library's confidence in the Bookkeeper
process, and in the beginning of 1996 a start was made with thetreatment of real library books (Report 1996).

Nurnberg variant
In the last few years a variant of the Bookkeeper process has beendeveloped in Germany by the company Libertec Bibliothekendienst
GmbH in Nurnberg. An interesting modification has been introducedin the treatment procedure: instead of using an organic fluid to apply
the effective agent, magnesium oxide (MgO), to the paper, MgO
deposition is mediated by air. The MgO powder is blown in frombelow the books, which are fanned open by the air current. The
duration of the treatment, which determines the amount of MgOapplied to the paper, is attuned to the initial pH value and the weightof the book. In a subsequent step, a current of air with a high relative
humidity is used to stimulate the absorption of the MgO into the

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Mass deacidification

paper. The Libertec installation has a daily capacity of approximately
200 books, with treatment costs per book of DM 15 (Bell, pers. comm.
1996).

Although research data are not yet available in published form,
satisfactory test results have recently been reported by the Bayerische
Staatsbibliotheek in Munchen (Trapp, pers. comm. 1996).

23
-21-

DEZ
Development
The basis of the diethylzinc (DEZ) mass deacidification method wasestablished by G.B. Kelly and J.C. Williams, co-workers of the
Library of Congress, Washington. From estimations in the 1980s, itappeared that a considerable number of books from the Library's
collections were in an extremely deteriorated state. Moreover, thisnumber would increase each year with 77,000 books (Johnson 1988).
According to the Library of Congress, none of the existing deacidifi-

cation techniques could be applied on a sufficiently large scale(500,000-1,000,000 books per year). As a consequence, the Library ofCongress took the initiative to develop a new and adequate system.
A gaseous deacidification agent was considered preferable, and out of

the studied organo-metallo compounds, diethylzinc proved to offer
the best prospects. Compared with liquid-phase deacidification, gaseous deacidification has the advantage, that many different objects canbe treated without the risk of damage to inks, dyes and adhesives.
After successful laboratory testing, the DEZ process was scaled up

at the General Electric Space Center, Valley Forge, Pennsylvania(Kelly 1987). Between 1981 and 1986, the system was tested in a pilot
plant at the NASA Goddard Space Flight Center. Partly in connection

with an accident during a test of the treatment chamber in 1985,
related to the very strong chemical reactivity of liquid diethylzinc,NASA withdraw from further investigation and the plant wasdismantled in 1986 (Johnson 1988, Sebera, pers. comm. 1996).
The chemical process industry offered a better setting for dealing
with these problems, and in 1988 Texas Alkyls (now part of AKZO
Chemicals, Inc.) was awarded a contract by the Library of Congress
to construct and operate a DEZ pilot plant in Houston, Texas.
In 1990 the Library of Congress invited proposals for mass deacidification of its endangered collections. Three systems participated (DEZ,
FMC and Wei T'o), and each performed test-runs on approximately
500 books which were evaluated by the Institute for Paper Scienceand Technology in Atlanta (Major 1991). Although none of the massdeacidification processes appeared to conform to the technicalrequirements defined by the Library in every respect, the DEZ system
was considered to offer the best prospects, especially with regard to
the efficiency of the process and the effectiveness of the deacidification.
Since 1992, the Library of Congress and other institutions in the
us and Europe have significantly contributed to the process of further

optimization of the DEZ process, by performing and evaluating of
testruns. In the sections on research results and applications moredetailed information on the results of the investigations and theinstitutions involved will be presented.
A dramatic turning point in the development of the DEZ process
was the decision of AKZO in 1994 to cancel further work on DEZ, due

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24

Mass deacidification

to lack of commercial prospects. In April 1994 the mass deacidifica-tion plant in Houston was closed, and AKZO terminated its DEZ
license with the us Commerce Department in September 1994. No
facilities are presently available to process materials utilizing the DEZ
process.

Research results
Initial damage problems in case of synthetic bookbinding materials
could be prevented by using spacers between the books, so that there
was room left between the bindings during the treatment procedure(Johnson 1988).

The first results of different tests performed by the Library ofCongress on various series of books indicated that DEZ treatment
achieves a complete and fairly homogeneous neutralization of the acidcomponents in the paper, irrespective of the type and concentrationof the acid and the sort of paper and bookbinding material. Accelerated ageing studies have shown that the DEZ treatment of different
sorts of paper causes a general and significant decrease in the rate ofpaper degradation, measured as change in the folding endurance(Sebera 1990).

With a final pH value of no more than 7.0-7.8 in the cold water
extract of the treated paper, the DEZ system offers one of the mildest

deacidification processes. Even very acidic books (pH < 3.0) were
neutralized sufficiently by the DEZ process, leaving adequate amountsof alkaline reserve in the paper. This advantage has been attributed to
the very fast diffusion and transport of gaseous deacidification agentsas compared to deacidification methods using liquid impregnation(Neevel 1991).

The alkaline reserve (1.8-2.5% CaCO3) has proved to be optimalfor the different sorts of paper studied, taking into account various

factors such as duration of treatment, process costs, effect on
permanence, and visible and morphological paper characteristics. The
alkaline reserve of the treated books showed a homogeneous distribu-

tion from sheet to sheet, with variations restricted to differences
between the margins and the centers of the pages, the margins having
slightly higher levels.
A disadvantage of the DEZ treatment is that zinc oxide appears toaccelerate the photochemical oxidation of cellulose (Kelly 1981,
Daniels 1990). This also applies to zinc sulfide, which may be formedby the reaction of zinc oxide with hydrogen sulfide (H25), sometimes

present as a component of polluted air (Neevel 1991). As theconversion of zinc oxide into zinc carbonate proved to decrease thesensibility of the treated paper to photo-oxidation, the original pilot
plant at General Electric applied an after-treatment of the books with

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25

Henk J. Porck

Treatment principle
Type of process

DEZ/gas-phase

Effective agent

Diethylzinc (DEZ;(C2H5)2Zn); DEZ is a liquid at room temperature and at
normal pressure. In gaseous form, at reduced pressure, it is used for thedeacidification process (Sebera 1990).

Procedure(0 Preconditioning: the books are placed on carts, spine down and separated
from each other by 10 mm spacers, and driven into the cylindrical steel
treatment chamber; preselection is confined to large-format books andstrongly coated paper, which need a separate, prolonged treatment; after
flushing the chamber with pure nitrogen gas, the books are dried for 20-30
hours at reduced pressure and 40-60°C, to decrease the water content of thepaper to approximately 0.4%.
(ii) DEZ treatment: after evaporation of liquid DEZ, the gaseous DEZ is
introduced into the treatment chamber and kept at reduced pressure for10-12 hours; when the weight of the books, which is continuously
registered, stabilizes, the flow of DEZ is stopped, after which the excess of
DEZ is removed and recycled.
(iii) Reconditioning: subsequent to the complete removal of DEZ by means offlushing with dry nitrogen gas and vacuum, water vapor is introduced into
the chamber for approximately 6 hours to accomplish the gradual regain of anormal water content in the paper; after return to atmospheric pressure, thechamber is opened and the books are removed.

Deacidification

Gaseous DEZ is very reactive with the strong and weak acids present inpaper. In the neutralizing reaction of DEZ with sulfuric acid, zinc sulphate(ZnSO4) and ethane gas (C21-16) are formed:

H2SO4 + (C2H5)2Zn -> ZnS 04 + 2 C2H6

The zinc sulphate deposits in the paper, while the ethane gas is removed,
together with the excess of DEZ in the second step of the treatment
procedure.
Alkaline reserve

With the controlled amount of water present in the paper, DEZ forms acontrolled amount of zinc oxide (ZnO) and ethane:
H2O + (C2H5)2Zn -> ZnO + 2 C2H6

Zinc oxide remains in the paper and forms the alkaline reserve, protecting
the paper against future acidification, as caused by air pollutants and paperoxidation. As there is a direct correlation between the water content of thepaper and the amount of zinc oxide formed, the preconditioning step,
resulting in a water content of 0.4%, guarantees an alkaline reserve of
1.5-2.0% zinc oxide (1.8-2.5% CaCO3).
In connection with the relative insolubility of zinc oxide in water, cold
extraction pH values of treated paper do not reach the very high levels foundfor magnesium carbonate in paper treated with other deacidification
processes.

carbon dioxide gas (CO2) (Kelly 1987). Those developing the systemfurther probably did not attach much importance to the aspect ofphoto-oxidation, as the after-treatment with CO2 was dropped later.
(Sebera 1990).

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Mass deacidification

In June 1991, the Institute for Paper Science and Technology(Atlanta) reported the results of the tests of the DEZ, FMC and Wei
T'o systems, performed by order of the Library of Congress on thebasis of the Library's request for proposals (RFP90-32). The test
material for each system consisted of approximately 500 books,
including a collection of test books that had been assembled torepresent a variety of modern papers (Lc blue test books). With

respect to the DEZ process, several of the findings are worth
mentioning. The treated books showed significant changes, such asodor, white residues, rings, cockling, (yellow) discolorations andadhesive bleeding. More than 90% of the books appeared to becompletely deacidified by the DEZ treatment, with final cold
extraction pH values ranging from 7.55-9.50 (mean value: 7.98) andalkaline reserve contents of 1.0-11.0% CaCO3. It should beemphasized that the high pH and alkaline reserve values found insome of the papers resulted from the fact that these papers werealready alkaline prior to treatment. Paper strength measurements andaccelerated ageing tests indicated that, with the exception of alkalinesized paper, the DEZ treatment improves the mechanical stability ofthe paper (Physical properties 1991a).
At Harvard University the problem of inhomogeneous deacidifica-tion of coated paper by DEZ was clearly identified in a test run of
3,700 books. Besides the problem of coated paper, the unpleasantsmell after the treatment, and the 'esthetic' damage of approximately
20% of the books, such as discoloration (Newton rings) and white
deposit on both paper and covers, were also distinguished as undesirable side effects. Moreover color changes, in particular in 19th-century

illustrations, and deleterious effects of the DEZ treatment on bookbinding materials containing cellulose nitrate were recognized asserious disadvantages (Mass deacidification 1993).
The findings of the Harvard University Library were confirmed by

the DEZ studies of the mass deacidification survey of the Schweizerische Landesbibliothek (National Library) and Bundesarchiv (Federal Archives), which were performed in cooperation with the Libraryof Congress and the Wimmis Pulverfabrik. Additional studies by the

Swiss, using accelerated ageing tests and measurements of paper
strength, clearly indicated a positive effect of DEZ deacidification on
the permanence of paper, even though sometimes an immediate lossof paper strength was observed as a direct result of the treatment.
However, in their final report it was concluded that neither the DEZ
process, nor the other process tested (FMC), met all requirements andthat further research was necessary to decide which mass deacidification system would be most suitable for the Swiss libraries and archives(Schlussbericht 1992).

-25- 27

Henk J. Porck

The DEZ process was tested and compared with the FMC and Wei

T'o systems by the Canadian Conservation Institute. Studies withsample books, put together from different grades of papers, showed
complete and homogeneous deacidification and moderately improved
chemical stability for several papers during accelerated ageing. On theother hand the DEZ treatment resulted in a decrease in stability ofalkaline- processed wood pulp and cotton offset papers, and also
caused relatively much damage to the books, including a very strong
odor (Burgess .1992, Kaminska 1994). Additional studies of theCanadian Conservation Institute in order to identify other problems
in the treatment of common library and archival collections haveindicated that the DEZ process causes serious damage to dry-transfer
media, cellulose acetate materials and new parchment (Tse 1994).
Investigations in Belgium, comparing seven mass deacidification

systems, concluded that the DEZ system was one of the mostpromising (Lienardy 1992, 1994). Satisfactory research findings are also

reported by the Central Research Laboratory for Objects of Art andScience in Amsterdam (Roelofs 1994) and by the Harry Ransom
Humanities Research Center, University of Texas at Austin (Kiesling1995).

Initial studies of the TNO Center for Paper & Board Research(Delft) dealt with the effects of DEZ on two reference papers and on
bound newspaper volumes, and with the process control of the DEZ
procedure (Deventer 1993a, Havermans 1993a, 1993b). Subsequently,
TNO performed quality checks of four DEZ treatment runs (1993/
1994) of archival materials from the Algemeen Rijksarchief (GeneralState Archives of the Netherlands). The quality tests were carried out
by the use of reference papers inserted between the original archival
materials packed in standard acid-free cardboard archival boxes. The
results of the tests indicated in general a homogeneous deacidification
and a sufficient alkaline reserve. A case of serious damage, noted in
the second run in 1993, stressed the importance of the drying step inthe treatment procedure and motivated the introduction of several
measures to improve packing of the materials. Although the effects of
the DEZ treatment on the mechanical performance of the paper was
not discussed in detail in the test reports, the recorded data on paper
strength measurements during accelerated ageing do not clearly show
an improved mechanical stability (Deventer 1993b, 1994).

Another series of tests on the effects of the DEZ treatment on

regular library books has been performed by the Koninklijke
Bibliotheek (National Library of the Netherlands). Besides theobvious advantages such as increased pH and increase in useful
lifetime, several important disadvantages were reported, such as
unpleasant odor of the treated books, local discolorations (Newton

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28

Mass deacidification

rings) on coated paper, uneven deacidification of thick books, andsevere damage to synthetic bookbindings (Pauk 1994).
As the expert advisory panel of the Library of Congress hadconcluded from the studies of the Institute for Paper Science andTechnology described above that the DEZ system showed the greatest

promise for meeting the Library's technical requirements, the firstphase of the Library's Mass Conservation Action Plan was devoted tofurther refinement of the DEZ process. On the basis of twelve runs in
the AKZO pilot plant in Houston it was concluded that the major
undesirable side effects of the treatment could be resolved by minor
adaptations, i.e. odor and chemical attack on some book covers could
be prevented by reducing the temperature during treatment, andrings/white deposits on coated papers could be eliminated bymaintaining a sufficiently high DEZ flow rate (Harris 1994).

Application
The extreme reactivity of DEZ makes it necessary for the wholeprocess to take place in a reactor that is strictly protected againstleakage. Highly trained personnel is another requirement, and theinstallation should preferably be located in an industrial area whereindispensable facilities such as a fire brigade and a security service areavailable. Apart from high reactivity there are no other environmental
or health risks associated with DEZ.
The requirements for safety, qualified staff and location result inhigh investment costs for the system (Sebera 1990). Estimates haveshown that the DEZ process can only be exploited commercially at aminimal capacity of 250,000 books per year. Such an installation
would require a floor-space of 180 m2 and could treat a total of atleast 6 million books, assuming a life of the installation of 25-30
years. At a capacity of 500,000 books per year, the treatment costs perbook have been estimated at $ 3.00-3.50, but the actual cost of thetreatment per book in the pilot plant was reported to amount to$ 9.00-13.00 in 1988 (Johnson 1988). Later reports mention costs perbook, exclusive of transport, of $ 15.00 (Stefansson 1993).
In 1992 the Library of Congress presented its 'Mass Deacidification

Action Plan' to the American Congress. This plan included further
optimization of the DEZ process and evaluation and testing of otherpromising deacidification technologies. The results of the first phaseof the Action Plan, the refinement of the DEZ process discussed
above, were reported in October 1994, 6 months after the closure of
the DEZ plant in Houston (Harris 1994).
In order to contribute to the testing of the application of the DEZ

process in practice, three other American libraries entered into
contracts with AKZO Chemicals, Inc.: the Milton S. Eisenhower-27-

Henk J. Porck

Library of Johns Hopkins University (Baltimore), Harvard University
Library, and Columbia University.

In 1991 the Milton S. Eisenhower Library signed a one-year
contract ($ 40,000) for the treatment of 4,000 books (Major 1991). The
costs per book have been estimated at $ 9.75, exclusive of transport
costs (approximately $ 1.00) (Stefansson 1993).

Harvard University Library, which has a long tradition ofcollection preservation, signed up for DEZ deacidification in 1992 andin the first year spent $ 65,000 for the treatment of 3,700 books and4,688 maps, at the costs of $ 12.40 per book and $ 4.35 per map,
inclusive of transport (Preserving 1991, Harvard 1992, Mass deacidifi-

cation 1993). Harvard University Library was the first institution
which reported test results discussed above of regular DEZ deacidification of books and maps (Mass deacidification 1993).
Columbia University received financial support of approximately$ 11,000 from the 'New York State Program for the Conservation
and Preservation of Library Research Materials' for the deacidificationand testing of 400 books, in cooperation with the New York
University and the State University of New York (Columbia 1993).
The withdrawal of AKZO from further exploitation in 1994 led to thedisappearance of DEZ from the mass deacidification scene, but serious

initiatives are being undertaken by the Rijksarchiefdienst (State
Archives of the Netherlands, The Hague) to breathe new life into the
DEZ system for preservation of archival materials (De muren 1996,
Steemers, pers. comm. 1996).

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30

FMC
Development
The FMC process has been developed by the Lithium Corporation ofAmerica (LITHCO) in North Carolina. This firm, being a part of the
FMC concern, has specialized in the development and the productionof organo-metallo compounds for many different applications. Since1988 FMC (Bessemer City) is involved in research on massconservation of paper (Wedinger 1989, Pacey 1992). On the basis ofresearch results FMC has developed a method by which books aretreated with carbonated magnesium alkoxide, solubilized in freon-113.

Although alkoxides are also used in the Wei T'o deacidification
process, described later, the particular alkoxide variant used by FMC,
MG-3, is said to result in deacidification as well as strengthening of
paper.

In the last few years, several changes have been made in thetreatment solution; MG -3 has been replaced by magnesium butyl
glycolate (MBG), and the freon by heptane. Because of these fairly
extensive modifications, the FMC process has entered into a renewedstage of testing ( Wedinger 1993).

Research results

FMC has enlisted an independent research institution to test theeffectiveness of their mass deacidification process. The Institute ofPaper Science and Technology in Atlanta has investigated the effectof the treatment on different paper properties, using accelerated ageing
experiments (Wedinger 1990a,b). The results obtained by the measurements of folding endurance and coppernumber (a measure for paper
deterioration) indicated a strong positive effect of the deacidification
treatment, i.e. the treated paper showed significantly less degradationcompared with untreated reference material. The strengthening effectwas evident as well: brittle paper with a fold number of less than 4,
yielded increased values up to more than 20 as a result of the treatment. The deacidification of the paper appeared to be homogeneous,
resulting in cold extraction pH values of 8.3-9.1, and an alkaline
reserve of 0.7-2.9% magnesium carbonate (0.8-3.4°k CaCO3).
Although predrying is a necessary step in the treatment procedure,
the required final water content (2%) is not as low as with processes

using DEZ (0.4%) and Wei T'o (0.5%). This means that more
vulnerable books, such as those with leather bindings, need not be
excluded from treatment. As the presence of alcohol, like methanol

in the case of the alkoxides used by Wei T'o, is not required tosolubilize the effective deacidification agent of the FMC process, therisk of damage to inks and adhesives is strongly reduced andconsequently preselection is less essential (Wedinger 1989).

As mentioned above, the FMC process was also included in an
investigation of the Institute for Paper Science and Technology-29-

EST COPY AVARABLE

31

Henk J. Porck

Treatment principle
Type of process

FMC /liquid -phase

Effective agent

MG -3, carbonated magnesium dibutoxytriethylene glycolate; MG -3 is describedamong other alkoxides in the FMC patent of 1989 (Kamienski 1990). In solubilizing

the alkoxides in an organic solvent, the carbonated form produces a solution witha relatively low viscosity, resulting in an improved impregnation of the paper,compared to the noncarbonated variants; recently MG -3 has been replaced bymagnesium butyl glycolate (MBG).
Solvent

Freon-113; recently replaced by heptane

Procedure

The original treatment procedure, which takes less than 8 hours for completion,
consists of three steps:(i) Predrying: the water content of the books is decreased to 2.0% by means of a
specially developed dielectric drying process.
(ii) Impregnation with MG -3: the books are placed in the treatment chamber andimpregnated for 10 minutes with a solution of MG -3 in an organic solvent (freon).
(iii) Aftertreatment: the treatment solution is drained and recycled, and theremainder of the solvent in the books is removed by means of dielectric drying; nofurther reconditioning is recommended.

Initial reactions

In the reaction of MG -3 with the water in paper, butoxyethylene glycol (BTG) andmagnesium carbonate (MgCO3) are formed:

MG-3 + H2O > 2 BTG + MgCO3
Deacidification

MG -3 can directly neutralize the acids in the paper, producing magnesium salt,
carbon dioxide and BTG. Both BTG and the excess of MG -3 are adsorbed by the
paper and linked to the cellulose chains, resulting in the strengthening of the paper(Wedinger 1989).

Alkaline reserve

The remainder of MG -3 and the produced magnesium carbonate build up thealkaline reserve, protecting the paper against future acidification.

(Atlanta), carried out by order of the Library of Congress. Several
findings are worth mentioning. The treated books showed significant
changes, such as odor, sticky residues on covers and spine, cockling,and (yellow) discolorations. Over 90% of the books appeared to beincompletely deacidified by the FMC treatment; final cold extraction
pH values ranged from 7.05-10.07 (mean value: 7.51) and the alkaline
reserve amounted to less than 0.3% CaCO3. Paper strength measurements and accelerated ageing tests indicated that, with the exceptionof alkaline-sized paper, the FMC treatment reduces the rate of loss of
mechanical strength of the paper. Indications for a strengthening effectas a direct result of treatment were not found (Physical properties
1991b).

The modified FMC process, using MBG in heptane, was also part of

the Swiss investigations by the Landesbibliothek (National Library)and Bundesarchiv (Federal Archives) in Bern mentioned earlier. The
results indicated that the predrying and afterdrying did cause damage
after all. This damage seemed to be related to uneven drying which30-3 2

Mass deacidificationin turn could lead to a non-homogeneous impregnation of the materials with the treatment solution and cause the uneven distribution of
the alkaline reserve observed in this study, as well as the prolonged
release of the solvent and other volatile (odorous) reaction products

after the treatment. Other undesirable side effects, such as local
discolorations, were also observed. On the basis of these results it was
concluded that the FMC process did not meet the requirements which
the Swiss institutions had established for a suitable mass deacidification system (Schlussbericht 1992).
The FMC process was tested and compared with the DEZ and Wei

T'o processes by the Canadian Conservation Institute. In this comparative study, which started in 1991, the FMC process was in a stageof development in which the treatment solution consisted of MG -3 in
heptane. Studies with sample books, put together from different
grades of papers, showed the following effects of the FMC treatment:complete neutralization of acid and good penetration of the deacidifi-

cation agent in the core of the paper, moderately homogeneous
distribution of the alkaline reserve, and improved chemical, and to alesser extent mechanical, stability during accelerated ageing. On theother hand the FMC treatment appeared to cause damage to all books
to some degree, resulted in a markedly increased absorbency of thetreated papers which might stimulate the reactivity of the paper tomoisture, and caused significant color change, i.e. yellow and translucent staining, of the paper (Burgess 1992, Kaminska 1994). Addition-

al studies of the Canadian Conservation Institute in order to identify

problematic materials commonly found in library and archival
collections have indicated that treatment with the FMC process causes
serious damage to wax seals, pencil crayons, color laser copies, newparchment and polystyrene materials (Tse 1994).
Several disadvantages of the FMC process found in the previously
mentioned studies were confirmed in the comparative investigation of

A. Lienardy, i.e. paper discolorations and an unpleasant odor of thetreated materials (Lienardy 1992, 1994).

Application
Safety and health risks of the FMC process appear to be relatively
small, highly qualified personnel is no prerequisite, and the installation can in principle be housed within a library or archive.
On the basis of a laboratory-scale installation reported by R.S.
Wedinger (1989), allowing treatment of 20 books at a time, plans foran operational pilot plant with a capacity of 100,000 books per year
and a commercial plant with a capacity of 1-3 million books per year
have been put forward. Since 1990 the pilot plant operates in North
Carolina with an actual capacity of 300,000 books per year. The

31 33

Henk J. Porck

treatment costs are calculated per weight and have been estimated at$ 14.00-30.00 per kg (Pacey 1992). So far, there are no further
developments in the commercialization of the present pilot plant(Wedinger, pers. comm. 1996).

Wei T'o
Development
The Wei T'o firm was founded in 1972 by R.D. Smith and started todevelop solutions of magnesium methoxides for the purpose of deacidification. This mass deacidification system resulted from R.D. Smiths'
Ph.D. thesis research into a nonaqueous deacidification treatment of
paper at the University of Chicago (Smith 1970).
Initially a pressurized solution of magnesium methoxide inmethanol and freon-12 (dichloro-difluoro methane, a chloro-fluoro
carbon, CFC) was used to impregnate complete books. For deacidification of separate sheets, this solution was supplemented with barium
methoxide, freon-11 (trichloro-fluoro methane) and freon-113 (trichloro-trifluoro ethane) and was used as a spray.

An important improvement in the Wei T'o system was thereplacement of the effective deacidification agent, magnesium
methoxide, by methoxy magnesium methyl carbonate (MMMC). Thisreplacement resulted in the reduction of several undesirable side effects

such as a white deposit on the surface of the treated paper andclogging of the spray guns. The improved Wei T'o reagent is used inseveral libraries and archives, both in large-scale deacidification byhand and in mass deacidification. Since 1982 the Wei T'o mass deacidification system is in operation at the National Archives and National

Library of Canada, Ottawa. A temporary cooperation of Wei T'owith Union Carbide was cancelled, presumably due to lack of commercial prospects (Neevel 1991).

As the use of methanol can cause damage to certain inks andadhesives, substantial efforts have been made by Wei T'o Associates,
Inc. (Matteson), to minimize the methanol content in the deacidifica-tion process and to find an adequate replacement. In addition, analternative for the freon compounds, which cause deterioration of theozone layer of the earth, must be found. Although freon-12 can be
replaced by the less harmful freon-122, and the Wei T'o mass deacidification is in principle a closed circuit process, environmental

restrictions for freons by the governments will ultimately result inserious problems in the exploitation of Wei T'o (Hon 1989, Schwerdt
1989).

Environmental regulations in Canada prohibited the use of freon
compounds (chloro-fluoro carbons, CFCs) in the beginning of 1996.

To allow the National Archives to meet the new regulations, theNational Research Council of Canada undertook a research project in
1993-94, to identify an adequate alternative for the Wei T'o solvent.
This resulted in the introduction of a new formula in 1995, in which
the original chloro-fluoro carbons (CFCs) are replaced by the moreenvironmentally acceptable hydrochloro-fluoro carbons (FicFcs).
However, in January 2000, environmental regulations will become
effective in Canada that prohibit the use of HCFCs in any process

33 35

Henk J. Porck

which does not totally prevent emission of this ozone-depleting
substance (Desmarais, pers. comm. 1996).

Research results
Tests with a small series of four books, using treated and untreatedcopies and accelerated ageing experiments, indicated a general
improvement of the permanence of the paper by Wei T'o deacidifica-tion (Smith 1987). Groundwood-containing paper showed more
benefit as compared to rag paper. More recent studies of Smith on
different sorts of paper confirmed the positive effect of the Wei T'otreatment (Neevel 1991).
The deacidified books appeared to be very alkaline, yielding cold
extraction pH values of up to 10.3. In addition, the alkaline reserve
introduced by the treatment amounted to 1.8-2.5% CaCO3 and hada reasonably homogeneous distribution. The individual sheets of abook showed no more than approximately 10% variation with themean value for this parameter.
Later reports indicate pH values of 8.5-9.5, and an alkaline reserve
between 0.7 and 0.8% CaCO3. Cases of uneven deacidification andwhite powdery deposits have also been found (Hon 1989, Harvey1993). The studies of Smith clearly indicated that groundwood
containing paper strongly increased in permanence, but later publications mention that these papers generally showed a slight discoloration as a result of the Wei T'o treatment (Harvey 1993).
A serious disadvantage of the Wei T'o system is the presence of

methanol in the deacidification solution. Certain binding media
applied in writing inks and adhesives dissolve in methanol, whichcauses irreversible damage. Besides, test results have indicated thatsome leather bindings can be seriously damaged by the predrying stepin the treatment procedure. As a consequence a preselection step isinevitable (Scott 1987); in a report of the Office of Technology Assess-ment and later studies, the amount of materials that has to be ex`
eluded from treatment is estimated at 20-30% of an average librarycollection (Johnson 1988, Brandt 1992).
The effects of the Wei T'o treatment were investigated in a 500
book test by the Institute for Paper Science and Technology (Atlanta),

by order of the Library of Congress. The treated books showedsignificant changes, such as odor, white residues, rings, cockling,(yellow) discolorations and adhesive bleeding. Approximately 35% of

the books appeared to be incompletely deacidified by the Wei T'otreatment; final cold extraction pH values ranged from 7.87-10.43(mean value: 8.93) and the alkaline reserve amounted to 0.3-4.0%
CaCO3. Paper strength measurements and accelerated ageing tests
indicated that, with the exception of alkaline-sized paper, the Wei T'o

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36

Mass deacidification

Treatment principle
Type of process

Wei T'o/liquid-phase

Effective agent

Methoxy magnesium methyl carbonate (MMMC)

Solvent

Mixture of methanol and chloro-fluoro carbons (cFcs); recently the CFCs havebeen replaced by hydrochloro-fluoro carbons (HcFcs)

Procedure

The Wei T'o mass deacidification process as applied at the Public Archives ofCanada consists of four steps (Smith 1987, Scott 1987):(i) Preselection: books with certain inks, adhesives and synthetic bookbinding
materials are excluded from treatment because of the risk of damage by methanol;
the books to be deacidified are placed, spine down, in special baskets, made of steel
wire.
(ii) Predrying: the books are dried for 36 hours using a combination of vacuum andhigh temperature (60-66°C), in order to decrease the water content fromapproximately 6% to 0.5%.
(iii) Impregnation: in a separate treatment chamber the books are impregnatedunder pressure with the MMMC deacidification solution for 60 minutes, after which
the solution is drained and recycled; subsequently the books are dried for 60
minutes under vacuum.
(iv) Reconditioning: the treatment chamber is brought to atmospheric pressure, andthe books are immediately placed in closed boxes for 24-48 hours, in order toprevent condensation of water on the surface of the books and to ensure a very
gradual return of a normal water content in the paper.

Initial reactions

Methoxy magnesium methyl carbonate (MMMC) reacts with the water in the paperand forms methanol (CH3OH) and alkaline magnesium carbonate, a mixture ofmagnesium carbonate (MgCO3), magnesium hydroxide (Mg(OH)2) and water:

CH30Mg000OCH3 + H2O -, MgCO3 + 2 CH3OH
CH30Mg000OCH3 + 2 H2O -> Mg(OH)2 + 2 CH3OH + CO2
4 MgCO3 + Mg(OH) 2 + 4 H2O -> 4MgCO3.Mg(OH)2.4H20
Deacidification &Alkaline reserve

The magnesium compounds formed by the initial reactions are able to neutralize
the acids in the paper, and build the alkaline reserve.

treatment improves the mechanical stability of the paper (Physicalproperties 1991c).

In a comparative study, the Wei T'o process was tested by the
Canadian Conservation Institute. Studies with sample books, consisting of different grades of papers, showed the following effects of the
Wei T'o treatment: complete neutralization of acid and good penetration of the deacidification agent in the core of the paper, moderately

homogeneous distribution of the alkaline reserve, and improved
chemical, and to a lesser extent mechanical stability during accelerated

ageing. On the other hand the Wei T'o treatment appeared to causesome damage to all books and to increase absorbency of the paper,
possibly caused by the removal of the initial sizing, which might

stimulate the reactivity of the paper to moisture (Burgess 1992,
Kaminska 1994). Additional studies to identify problematic materials-35-

EST COPY AVAILABLE

37

Henk J. Porck

commonly found in library and archival collections have indicatedthat the Wei T'o process causes serious damage to wax seals, color
laser copies and new parchment bookbindings (Tse 1994).
Several of the disadvantages described in the investigations mentioned above were confirmed in a comparative Belgian study, i.e.
bleeding of inks and limited homogeneity in the distribution of thealkaline reserve (Lienardy 1992, 1994).

Application
The Public Archives and National Library of Canada have been
applying the Wei T'o mass deacidification technique since 1982. The

low safety risks of the Wei T'o system have enabled installation
directly on location, resulting in low transportation costs. The built-in
plant does not require highly qualified personnel and occupies a floor-

space of 120 m2. Although 260,000 books can be treated per year
(5000/week) if the installation is used in continuous operation, theactual number of books treated per year is on average 40,000, at
approximately $ 7.00 per book (Johnson 1988). In the 1992 report of
A. Pacey an amount of CAN $ 8.33 is mentioned (Pacey 1992).
Although the Wei T'o system was developed initially as a pilot
project by the National Archives for the purpose of treating archival
as well as library material, it has become clear that the method is not
appropriate for archival material. In recent years operation of thesystem has been entirely for the benefit of the National Library ofCanada (Desmarais 1994).

Since the start in 1982, over 890,000 books have been treated.
Priority is established by the National Library and is as a rule given
to new acquisitions printed on acid paper. Because of the compositionof their material some synthetic covers might be affected by the heat

used in the predrying, and books with such covers are therefore
excluded from treatment. Exclusion of other material is mostly related
to ink solubility, especially from photocopies and most laser printers(Couture, pers. comm. 1996).
At the moment the National Archives do not expect to be able tomeet the new environmental regulations for the solvent applied in theprocess, which are expected to come into effect in January 2000; as aconsequence it is likely that they will be forced to discontinue theoperation of the mass deacidification system (Desmarais, pers. comm.
1996).

Sable variant
Since 1987, the Bibliotheque Nationale de France (National Library,
Paris) has been using a mass deacidification facility in Sable-sur-Sarthe

36 asMass deacidification

which operates on the same principles as the Wei T'o system. The
Wei T'o deacidification reagents and the treatment procedure havebeen developed further ever since the beginning of the 1980s(Schwerdt 1989). In pursuing the optimization of the Wei T'o system,
the Bibliotheque Nationale de France cooperated with the Centre deRecherche sur la Conservation des Documents Graphiques and the
CIM-MALLET firm. Important technical improvements have been
made with respect to the recycling of the deacidification solution. The
treatment solution consists of a mixture of carbonated magnesium
methoxide and ethoxide in alcohol, utilizing freon-134a (tetrafluoro
ethane) as co-solvent (Flieder 1989, Brandt 1992, Val las 1993).
As in the Wei T'o system in Canada, the treatment procedure in

Sable is relatively time consuming, taking 3-4 days including
predrying and reconditioning (Dubouloz 1992).
Only few results of investigations into the effectivity of the French
Wei T'o variant have been published. In a comparative investigation
in Belgium it has been shown that the Sable process suffers from thesame side effects on inks as have been reported in the Canadiansystem, and that therefore preselection of the material to be treatedis a necessity (Lienardy 1992, 1994). It has also been noted thatmaterials with a very high acidity, showing pH values of less than 3.3,
cannot be deacidified sufficiently (Brandt 1992, Val las 1993).
The original plan was for treating 200,000 books per year, but thishas not yet been achieved. In the pilot plant 25,000 books (onlyrelatively small-sized volumes) are deacidified per year. The costs perbook have been estimated at $ 5.00-15.00 (Stefansson 1993). In 1989
the French Wei T'o system in Sable was commissioned to start withthe treatment of the endangered 19th and 20th century collections of

the Bibliotheque Nationale de France. The selected books will bemicrofilmed, deacidified and, if necessary, restored (Schwerdt 1989,
Dubouloz 1992, Val las 1993).

Further developments in the mass deacidification process of the
Bibliotheque Nationale are in progress, both in the Centre de Sable
and in the Centre Technique de Marne-la-Vallee. The process underdevelopment uses supercritical carbon dioxide and is aimed at a
combined deacidification and strengthening of paper. Pilot investigations by the CEA (Commissariat a l'Energie Atomique) have resulted
in a patent, and an exclusive license has been granted to the French
company Separex. The development project is partly supported by an
innovation loan from ANVAR (Agence Nationale pour la Valorisationde la Recherche). Results of the research program are not yet available
in published form, and the internal reports are strictly confidential(Brandt, pers. comm. 1996).

Other initiatives
Biickeburg process
The Biickeburg process in the Niedersachsisches Staatsarchiv (State
Archives) in Biickeburg (Germany) has been developed for large-scaledeacidification and combined strengthening of archival materials
consisting of single sheets of paper. The process involves a sequenceof three steps: (i) fixation of the inks and dyes, (ii) aqueous deacidifica-tion by means of a solution of magnesium bicarbonate, and (iii)
strengthening by methyl cellulose sizing.
The tests performed in the experimental stage of development haveindicated that the treatment of paper results in an increase of the pH
value to 9.4-10.7, an alkaline reserve equivalent to 2.0% CaCO3, anda reduced loss of mechanical stability during accelerated ageing. Workis still in progress, in cooperation with a commercial firm, to optimize
the system.

Since the end of 1995 the process has been operational at the
Buckeburg Archive. The capacity amounts to approximately 5 linear
meters of archival material (approx. 50,000 sheets) per 30 days. So far
only post-1850 materials have been treated, while several types of
paper have been excluded, such as paper weighing more than 140
g/m2, oversized sheets, photographs, zinc oxide copies, and brittle
paper (Feindt, pers. comm. 1996).

Graft-copolymerization process
The graft-copolymerization technique is used to strengthen cellulose
by means of polymerization of monomers which are introduced in
the paper fibers. The possibility of polymerizing mixtures of styrene,

methyl methacrylate and ethyl acrylate by means of uv or gamma
radiation for the purpose of paper conservation was already reported
25 years ago (Davis 1981). Since then the British Library has instigatedresearch in order to adapt the graft-copolymerization process, which

had been tested on separate sheets of paper, to the treatment ofcomplete books, using mixtures of ethyl acrylate and methyl methacrylate and applying gamma radiation (Burstall 1984, 1986). In 1988
the British patent was obtained (Mol lett 1988). Though substantial
research has been done in the course of time, the treatment process
is not yet fully optimized and still remains in an experimental stage.
At the moment the British Library is seeking for new funding tocontinue the further development of the graft-copolymerization
process (Mehmet, pers. comm. 1996).
The treatment procedure consists of 7 steps: (i) 5-10 books to betreated are placed in a special container; (ii) the container is flushedwith nitrogen gas in order to remove the oxygen, which can inhibit
the polymerization reaction; (iii) solubilized acrylate monomers, theamount depending on the weight of the books, are introduced; (iv) thebooks are treated with the monomer solution for several hours to

-38-

40

Mass deacidificationachieve a uniform impregnation; (v) the container with the books is
exposed for 13-16 hours to a gamma radiation-emitting, radioactive
cobalt source, causing the monomers to polymerize and to link to thecellulose molecules; the process is followed by registration of theweight of the books and the temperature, which can go up to 65°C;(vi) excess of monomers is removed by evaporation, using air flushingof the container; (vii) the books are removed from the container andreconditioned in a well-ventilated storage room.

Satisfactory results were reported with a 5:1 mixture of ethyl
acrylate and methyl methacrylate monomers. Addition of small
amounts of alkaline monomers could bring about deacidification of
the paper, and traces of other monomers increased the effectiveness ofthe treatment (Mollett 1989).
Several investigations have indicated that paper strength, measured

as fold number, increased considerably as a result of the treatment.
Groundwood-containing paper and naturally aged paper which had

already suffered from deterioration showed the least effect. The
standard treatment procedure did not cause bleeding of inks, nordamage to various bookbinding materials. The polymers caused a gain

in weight of 15-20% and showed a fairly homogeneous distribution
over the individual pages of the treated books. As the radiation doseneeded for optimal effectiveness has to be adapted to the dimensionsof the books to be treated, relevant statistical data have been collectedin advance from the British Library collections for future treatments(Butler 1989).

Apart from the safety risks associated with the use of radioactive
sources, which necessitates employment of specially trained staff, noserious health risks have been reported. It has been estimated by thedesigners of the system that the treatment costs per book would
amount to $ 5.00 in an installation with a capacity of 100,000-200,000

books per year (Johnson 1988). Although the development of acommercial installation, exploiting the graft-copolymerization process
on a mass scale, has been planned, the operational phase has not yet
been reached.

Paper splitting process

For many years, the conservation department of the Deutsche
Biicherei (Leipzig) has made substantial efforts to mechanize single
steps in restoration procedures and constructed the first mechanizedinstallation for the aqueous treatment of paper (Wachter 1986,
Rotzsch 1988).

The paper splitting process has been developed over the past 25

years by W. Wachter at the Deutsche Biicherei in Leipzig, incooperation with the Friedrich-Schiller Universitat in Jena, Germany.

39
41

Henk J. Porck

Though basically a system for the treatment of loose sheets of paper,
it can also be used for books by separating the sheets of paper firstand rebind them after treatment. In principle, sheets of paper are
strengthened and deacidified by means of the following procedure: (i)on both sides of the paper, sheets of filter paper are pasted, using a
mixture of gelatine and glycerine as adhesive; (ii) by pulling the two
sheets of filter paper apart, the paper to be treated is split in two; (iii)
after insertion of new, thin polyester-containing paper, both halves ofthe split paper are pasted together again, the new paper forming astrengthening central layer; the adhesive used in this step consists ofcarboxy methyl cellulose, to which calcium carbonate, as deacidification agent, and acrylate compounds, as paper strengthening agents, areadded; (iv) subsequently the gelatine/glycerine layer and attached filter
papers are enzymatically removed, and the papers are dried.
By the use of a continuous leafcasting machine, joining the paper

sheets to be treated, and moving belt principles, the paper splitting
process has been almost entirely mechanized, enabling large-scale
application. The Deutsche BUcherei, the Technische Universitat
Chemnitz, the Landesarchiv Baden-Wurttemberg in Stuttgart and thefirm Fa. Becker Verfahrenstechnik in Korb are working on theconstruction of the installation located in the building of the Deutsche
BUcherei. For the development and construction of the installation,

the German Bundesministerium fur Forschung and Technologie
offered financial support to the amount of DM 1.3 million (Deutsche
Biicherei 1993). While the main part of the installation has alreadybeen completed, work on the final stage, the removal of thegelatine/glycerine layer and attached filter paper, is still in progress(Wachter, pers. comm. 1996).
Although optimization of the paper splitting installation in theDeutsche BUcherei is still in progress, the results obtained so far intreating newspapers are very promising. At the present level ofmechanization and automatization, 2,000-4,000 sheets of paper can betreated daily, at an estimated cost of $ 1.00 per sheet (Bund-LanderArbeitsgruppe 1992, Weber 1992).
At present a paper splitting installation is also being constructed in
Ludwigsburg, while plans for construction have been put forward by
the Garchinger Speicherbibliothek in Germany (MUcke 1989, Mann
1994, Weber, pers. comm. 1996).

Vienna processThis process has been developed in the early 1980s by 0. Wachter onbehalf of the Austrian Nationalbibliothek (National Library, Vienna).
It is intended for the combined strengthening and deacidification ofbound newspapers (Wachter 1987b, Cunha 1989).

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Mass deacidification

The treatment procedure consists of the following steps: (i) the
newspaper volumes are disposed of their bookbindings and divided in

4 cm thick bookblocks, which are placed in a cylindrical vacuum
chamber; (ii) under vacuum the bookblocks are drained with anaqueous solution of methyl cellulose and polyvinyl acetate asstrengthening agents, and calcium hydroxide or magnesium carbonate
as deacidification agent; (iii) the wet bookblocks are quickly frozen atminus 40°C and subsequently freeze dried; (iv) after reconditioning tonormal pressure, temperature and humidity, the newspaper blocks arerebound.
The treatment results in an increase of paper strength of up to 4.0
times the original value, measured as folding endurance. There appears
to be an evident washing effect due to the aqueous treatment; printing
inks show no bleeding damage. Results of accelerated ageing tests havenot been reported.
In 1987 the Austrian National Library started a large-scale project,

aimed at the treatment of 3,000 newspaper bookblocks per year($ 15.00 per bookblock), using the Vienna process equipment, whichis integrated in the library (Johnson 1988, Lienardy 1994). At the
moment approximately 42 newspaper volumes can be treated in 10
days. Especially the freeze-drying step is very time consuming, and theapplication of supplementary freeze dryers is considered to increase

the output. A full description of the treatment procedure and theresults of test research will be published shortly (Ruhm, pers. comm.
1996).

43-41-

Evaluation
The role and merits of mass deacidification in preservation of library
and archival materials have received a great deal of attention in thelast decade. Several crucial issues have induced heated discussions;various, sometimes contradicting views, have been put forward in thespecialist literature and elsewhere and caused considerable confusion.
The primary points of controversy relate to:i. the necessity of preselection of materials to be treated;
ii. the actual contribution of deacidification to the permanence of
paper;
iii. the reluctance of institutions to make use of available mass deacidification methods, andiv. the place of mass deacidification within the whole field of(mass) preservation activities.

In the following, these four aspects, presented in the form of questions, are discussed on the basis of the relevant data on the main massdeacidification systems collected in this report. In addition, opinions
of a number of experts, who have been asked for their comments on
the basis of a questionnaire, have been incorporated.
1: Which materials will actually benefit from mass deacidification,
and which materials have to be excluded from treatment?
There appears to be a general consensus on the type of paper that
benefits most from deacidification: paper which is acidic, such as
alum-rosin-sized and groundwood-containing paper, paper produced
under acidic conditions, and paper of all types which has become
acidic through pollution. If such papers are still strong enough to be
used, then mass deacidification can be expected to prolong their usefullife. However, if they are already brittle or very weak, deacidification
alone cannot be expected to recover their usefulness.

The idea that brittle paper should not be mass deacidified iscontradicted by some research indicating that deacidification of suchmaterials can significantly slow down their rate of degradation. It
would be preferable to reformat all brittle paper as soon as possible,
but the reality is that funding limitations and logistics simply do notallow this. From this perspective, by reducing further degradation
mass deacidification could 'buy precious time' for the preservation ofbrittle materials.
Both the research results and the application data of the main massdeacidification processes show that a preselection step appears to beunavoidable for all systems. Preselection criteria depend upon thestrength and weaknesses (limitations) of the respective deacidification
process. The serious problems specific materials present when treatedby a particular process argue strongly for their exclusion fromtreatment by careful preselection. In general, the materials that havereceived most attention in this respect include coated paper, (writing)inks, dyestuffs, oversized (thick) books, leather, parchment and
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44

Mass deacidification

synthetic bindings. Although efforts to refine the techniques used in
the individual processes have of course focused on these specificproblems and improvements in the treatment process have often beenrealized in the course of time, this is not the place to judge thesignificance of these improvements and the benefits they may provide.
A type of paper to which insufficient attention has been given so

far is pigment-coated paper for printing, which is found in many
books and increasingly so today; not much is known about the special
problems these papers might pose in mass deacidification processes.

Modern papers in general will hopefully not create similar
problems in the future if they are made to one of the new standards

for 'permanence'. It should be mentioned in this connection that
there seems little point in indiscriminately treating any new acquisition, even when it has obviously been printed on non-acidic paper. It

has been said that we will have to select out and avoid treating
materials printed on alkaline and permanent papers, and the preceding
sections dealing with applications of the various processes show that

this is indeed sometimes done. The argument 'if it does not do any
good, it does not do any harm either' may in fact not apply to the deacidification of weakly acidic and non-acidic paper. This problem maylie with the high alkalinity that can be reached by treatment,
especially with liquid-phase deacidification systems. There are serious
concerns about the long-term effects of the resulting high pH values

on the chemical and mechanical stability of these papers, and thisissue deserves further investigation.

2: What is the real quantitative contribution of deacidification to
the permanence of paper?
With all mass deacidification processes discussed in this study,
treatment has a positive effect on the permanence of paper in the longterm, which means that with the use of accelerated ageing tests incombination with paper strength measurements it has been shownthat degradation of treated paper is slowed down, compared withuntreated reference papers.
On the other hand, the research results reviewed in the preceding
chapters have also indicated that despite this long-term positive effect,often a loss of paper strength is caused as a direct, immediate result of
deacidification, an effect that varies in magnitude with the different
mass deacidification systems. Questions with regard to the practicalconsequences of this reduction in mechanical stability and the amountof time it will take to reach the turning point when the treated paper

will have a better performance than the untreated, cannot yet beanswered.

The quantitative assessment of the increase in useful lifetime that
can actually be achieved by the treatment is also a complex issue and43Henk J. Porck

is primarily connected with the reliability of artificial ageing tests.
Although the real prognostic value of these tests is often seriously
doubted, for instance because standard accelerated ageing experiments
do not take into account several factors that will have an influence inpractice, such as air pollutants and use, it must be emphasized thatthese tests are at the moment the best measure available of how
papers deteriorate under certain conditions.
The extant differences in requirements and specifications established for (mass) deacidification processes lead to confusion and tomisinterpretation of research results. Therefore, for the sake of areliable and useful evaluation of the impact of deacidification on paper
permanence, there is an urgent need for standardization of both eval-uation criteria and test methods, and for further research into the`translation' of artificial ageing into practice.

3: Is it justified to wait for an 'ideal' mass deacidification method
or can/must we start now?
None of the existing methods conforms to the requirements of agenuinely 'ideal' mass deacidification process, as it has been shown
convincingly that each system has both its strengths and weaknesses.
Besides the safety and d environmental risks connected with some of thedeacidification agents and/or the solvents used, the limitations, moreor less severe for the different systems and the different materials
treated, vary from non-homogeneous deacidification to side effects

hazardous to the paper and/or bookbinding material, including
discolorations, color changes, staining, Newton rings, odor, bleedingof inks, dyestuffs and adhesives, and morphological changes (bubbling,cockling, change of 'feel). Optimization efforts focus on theselimitations, and test studies have often been carried out over a periodof years on plant units which have gradually evolved from theprototype to the pilot stage. As research reports on the efficiency andeffectiveness of the mass deacidification processes do not always
accurately indicate the precise stage of development of the system
under study, research results cannot be always interpreted reliably.
If there is some reluctancy with libraries and archival institutions
to apply mass deacidification, this cannot be explained only by thefact that there is no 'ideal' method or by lack of money. Perhaps anadditional problem is introducing into a library community what isessentially a chemical engineering process. However, a 'wait and see'policy cannot be recommended as it has been shown that this will
inevitably cause companies to withdraw and give up work on systems

for the commercial market, which eventually might result in theundesirable situation that further development of promising techniques will no longer be possible at all.

44

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Mass deacidification

Many of the current objections to mass deacidification techniquesin fact lose their validity once it is generally agreed that any 'mass'process should be applied only to non-unique objects of low intrinsic
value. If the preselection process screens out the intrinsicly valuable
materials, which should be treated individually, the problems reported
for mass deacidification systems can be considered minor comparedto the benefits. The time lost in worrying about these minor problems may represent a substantial portion of the lifetime of many ofthe materials to which the treatment could be applied.
Taking into account the specific nature of their collections and thefinancial and organizational conditions, institutions should be able todecide on the basis of existing knowledge about possibilities andlimitations of the currently available mass deacidification techniques
which of the systems optimally fits their needs and to what extent
they could make use of its service. It should be stressed that regularand independently performed tests and quality control of the treatedmaterials will remain an essential requisite. A useful and exhaustive
overview of the various evaluation factors which should be taken into
account in choosing mass deacidification processes has been publishedby the CPA (Sparks 1990).

4: What is the place of mass deacidification in the whole field of(mass) preservation activities?
The current application of mass deacidification techniques in practiceshows clearly that mass deacidification is no longer considered as apanacea. In general, institutions using mass deacidification treatment
also take other mass preservation measures, such as creating optimal
storage conditions and microfilming.

Mass deacidification can be considered to a large extent as a`preventive preservation' measure, which should become integrated

into an institution's preservation culture and should be viewed
primarily as a complementary preservation option in a balanced
institutional preservation program. However, within the frameworkof preservation of library and archival materials, mass deacidification
will have an essential place, as it is evident that, given the costs andtime involved, single-sheet deacidification cannot cope with theenormous amount of acid paper from the 19th and 20th century. Massdeacidification is a relatively inexpensive method to preserve the large

amount of 'normal' books published in the time of acidic paper
production.
Besides environmental control, mass deacidification can be qualified

as a true 'mass' process and it stands alone as the one mass processthat can be used on a huge number of objects which can be confidently assumed to have a specific problem in common: acid.

45-4

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List of contacts
Bakowska, A., Archiwum GlOwne Akt Dawnych, Warsaw, Poland
Bansa, H., Bayerische Staatsbibliothek, Bavarian State Library,
Miinchen, Germany
Baron, G., Staatsbibliothek zu Berlin, Berlin, Germany
Bartholdy, N.G., Statens Arkiver, Riksarkivet, Copenhagen, Denmark
Behrens, U., Department Papersave, Battelle Ingenieurtechnik GmbH,
Eschborn, Germany
Bell, 0., Libertec Bibliothekendienst GmbH, Nurnberg, Germany
Berninger, E.H., Deutsches Museum, Miinchen, Germany
Bierwagen, M., Bibliothek fur Bildungsgeschichtl. Forschung, Berlin,
Germany
Bjordal, L., Uppsala University Library, Uppsala, Sweden
Brandt, A.-C., Bibliotheque Nationale de France, Paris, France
Burd, J.E., Preservation Technologies, Inc., Cranberry Twp, PA, USA
Calvini, P., Soprintendenza ai Monumenti, Genoa, Italy
Coates, P.R., South African Library, Cape Town, South Africa
Couture, R., National Archives of Canada, Ottawa, Ontario, Canada
Crocco, S., Pittsburgh Theological Seminary, Pittsburgh, PA, USA

Desmarais, E., National Archives of Canada, Ottawa, Ontario,
CanadaDeter, I., Max-Planck-Institut fur Europaische Rechtsgeschichte,
Frankfurt, Germany
Dettmer, K., Landesarchiv, Berlin, Germany
De Vos, W., Koninklijke Bibliotheek Albert 1, Brussel, Belgium
Dorsten, J.v., Archimascon B.V., Rotterdam, The Netherlands
Durovic, M., St6tni Ustredni Archiv, Central State Archives, Prague,
Czech Republic
Erdmann, J., Landesbibliothek, Coburg, Germany

Erhardt, D.W., Conservation Analytical Laboratory, Smithonian
Institution, Washington, DC, USA
Erlande-Brandenburg, A., Archives de France, Paris, France

Faber, W., Archiwim GlOwne Akt Dawnych, Warsaw, Poland
Feindt, W., Niedersachsisches Staatsarchiv, BUckeburg, Germany
Foot, M.M., British Library, London, United Kingdom
Frieder, R., Northwestern University Library, Evanston, IL, USA
Frojd, I., Uppsala University Library, Uppsala, Sweden
Ganser, J., Bundesarchiv, Koblenz, Germany
Gaydos, R.M., Preservation Technologies, Inc., Cranberry Twp, PA,USA

Gonsalves, J.S., Institute da Biblioteca National, Lisbon, Portugal

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Mass deacidification

Graf von Duerckheim, M.E., J.S. Gericke Library, University of
Stellenbosch, Stellenbosch, South Africa
Gubkin, S., Case Western Reserve University Library, Cleveland, OH,
USA

Harris, K.E., Library of Congress, Washington, DC, USA
Havermans, J.B.G.A., TNO Center for Paper & Board Reserch, Delft,
The Netherlands
Herion, S., Schweizerische Landesbibliothek, Swiss National Library,Bern, Switzerland

Hernandez, F., Bibliotheca Nacional, Madrid, Spain
Hoel, I.A.L., Royal School of Librarianship, Copenhagen, Denmark
Hofenk de Graaff, J.H., Central Research Laboratory for Objects of
Art and Science, Amsterdam, The Netherlands
Hofmann, R., Bundesarchiv, Koblenz, Germany

Jordan, S., Hesburgh Library, University of Notre Dame, Notre
Dame, IN, USA

Kastaly, B., National Szechenyi Library, Budapest, Hungary
Kellerhals, A., Schweizerisches Bundesarchiv, Swiss Federal Archives,
Bern, Switzerland
Kellerman, S., Pattee Library, Pennsylvania State University, University Park, PA, USA
Leichert, G., Universitatsbibliothek Mannheim, Mannheim, Germany
Liers, J., Deutsche Bibliothek, Deutsche Biicherei, Leipzig, Germany

McIntyre, J.E., National Library of Scotland, Edinburgh, United
Kingdom

Mehmet, S., British Library, Londen, United Kingdom
Nebiker, R., Schweizerisches Bundesarchiv, Swiss Federal Archives,
Bern, Switzerland
Olszewski, A., Cleveland Public Library, Cleveland, OH, USA
Palm, J., Kongelige Bibliotek, Royal Library, Copenhagen, Denmark
Paulusov, H., St6tni Ustredni Archiv, Central State Archives, Prague,
Czech Republic
Peltikoglou, V., National Library of Greece, Athens, Greece
Priest, D.J., Knutsford, Cheshire, United Kingdom, retired from:,
U.M.I.S.T., Manchester, United Kingdom
Ruhm, W., Osterreichische Nationalbibliothek, Austrian National
Library, Vienna, Austria
Schoonmaker, D., Oberlin College Library, Oberlin, OH, USA
Sebera, D., Preservation Consultant, 209 Tenth Street SA, Washington, DC USA-53-55

Henk J. Porck

Shahani, C.J., Library of Congress, Washington, DC, USA
Staub, K.H., Hessisches Landes- and Hochschulbibliothek, Darmstadt,
Germany
Steemers, T.A.G., Rijksarchiefdienst, State Archives of the Netherlands, The Hague, The Netherlands
Trapp, C.-M., Bayerische Staatsbibliothek, Bavarian State Library,
Miinchen, Germany

Wachter, W., Deutsche Biicherei, Deutsche Bibliothek, Leipzig,
Germany
Walter, K.L., Love Library, University of Nebraska-Lincoln, Lincoln,
NE, USA

Weber, H., Landesarchiv Baden-Wiirttemberg, Stuttgart, Germany
Wedinger, R.S., FMC Corporation, Bessemer City, NC, USA
Welle, W.-D., Bundesarbeitsgericht, Kassel, Germany

Wenzel, H.-H., Department Papersave, Battelle Ingenieurtechnik
GmbH, Eschborn, Germany
Wolf, J.R., Hessisches Staatsarchiv, Darmstadt, Germany
Zappala, A., University di Udine, Udine, Italy
Zappall, M.P., Instituto Centrale per la Patologia del Libro, Rome,
Italy

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The Commission on Preservation and Access
1400 16th Street, NW, Suite 715
Washington, DC 20036-2217
Phone (202) 939-3400 0 FAX (202) 939-3407
World Wide Web site: http://www-cpa stanford.edu/cpa.html

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