The Abbey Newsletter

Volume 14, Number 5
Aug 1990

Nonaqueous Deacidification at Princeton, 1982-89: A Progress Report

by Susan Sayre Batton
Head of Treatments, Princeton University Library, 1985-90

The Deacidification Unit at the Princeton University Library was conceived and designed in 1982-83 by Robert Parliament (Head of Conservation 1981-85) as a large-scale approach to nonaqueous deacidification. This project began as an attempt to address the well-documented problem of acid deterioration in paper-based collections. Technical and informational data an our system is available in many published sources, including Parliament's paper in the AIC 1983 Book and Paper Annual, "Construction and Start-up of the Deacidification Unit at Princeton University Library' and the recent Library Technology Report (v.25 #1), "Mass Deacidification for Libraries: 1989 Update," by George Cunha.

After six years of operation, and over a million and a half leaves, sheets, and flat paper objects deacidified, I initiated a research project to 1) evaluate our program through testing samples of paper treated since 1983, and 2) describe the history of our program, explain why we have scaled down operations, and make future recommendations.

The following report is a version of a longer piece submitted to the Princeton University Library Administration. It was prepared to share information about our program with the wider conservatism community, and covers the start-up of our program at Princeton, our production results, administrative concerns and problem, questions and observations about Wei T'o (the deacidification agent we use), and a s of the 1989 testing project results.

Start-up at Princeton

The initial paper deacidification project began after the construction of the laboratory in 1983. The system was designed to use Wei T'o in a designated area using five spray booths connected to a complex and efficient ventilation system. The spray delivery system, at that time, was a sophisticated combination of readily available spray technology multiplied times five, to allow operators a continual flow of Wei T'o solution with adjustments at individual spray booths. This allowed the chemical to be decanted and maintained under pressure at a central pressure pot, rather than having a heavy container of Wei T'o solution attached to each gun. This system worked extremely well and afforded a great deal of operator comfort.

It is important to note that the refinements in the Soft Spray delivery system that Wei T'o currently markets were not available until 1985-86. Part of the Soft Spray development process involved testing an airless gun for the solution in an actual deacidification production setting at the Princeton University Library, during 1984. Innovations resulting from this testing were the teflon inserts to reduce dripping and the screen to filter out particulates. We tested two guns (the first of which was too heavy and awkward), to find the gun that is now in use.1

The first treatment project was part of a larger grant-funded effort to survey, catalog, microfilm and construct protective enclosures for three collections within the Department of Rare Books and Special Collections. A complete survey documenting the physical condition of each item was made in three months by six members of the Conservation Services staff. These collections were Western Americana, the Miriam Holden Collection on the History of Women, the Parrish Collection of Victorian Novelists, and the Edwardian novels. After the survey, a cutback in available funds allowed only two collections to be chosen for deacidification: the Holden Collection, because of the scarcity of these item, and the Edwardian novels, because of their uniqueness to Princeton and a consistent middle-to-low grade paper quality. Each item was reviewed prior to treatment, tested for pH and considered for other factors, including paper strength, age of the paper, discolorations, media other than print, etc. Richard Frieder was hired as the Head of Treatments (1983-85) to supervise the Deacidification Unit full time, to train staff, maintain system, and sort and pretest materials. Items in this project were carefully considered, and complete records were kept, noting date of treatment, bibliographic data, and number of leaves treated. This procedure worked well, both in term of effective treatment and control of items as they moved back and forth between Rare Books and the deacidification lab. After completion of this project, there was a cutback in preservation staff, and the Head of Treatments supervised the Book Repair Unit with 2.5 FTE, in addition to a scaled-down deacidification program.

The next project for the deacidification program was called the Serials Treatment Review (STR). This program began as a way to systematically review all unbound serials printed on newsprint or inferior papers, and was intended to direct binding and conservation dollars to items with the greatest long term importance to the research collections, thus avoiding spending money on little-used materials.2 After these serials were identified in the Conservation De t, selectors were given a number of options including: downgrade binding case style, deacidify and bind, microformat, discard, or cease ordering. In theory, STR decisions were based on a paper condition assessment, but with reductions in staff and other problem, this was not always fully accomplished. Then in 1985, Parliament and Frieder left Princeton, and the department was reorganized and r . Cynthia Clark became the Binding and Related Services Librarian, and Susan Batton became the Head of Conservation Treatments, with full responsibility for the deacidification program.

This reorganization brought to light many problems with the STR. A new Preservation Specialist was hired to coordinate pH testing and sorting, which consisted of making visual observations about the paper which might rule out the Wei T'o solution as an option: brittle or coated paper, risky inks, papers from the Near East or India (which often discolor), etc. After testing, all results were recorded in a standard way in the Serials Binding Record, and then communicated to the appropriate subject selector. The final decision was made by the subject selector based on Preservation recommendations, and this was recorded in the permanent record.

The STR was only one of several systems established to address large-scale projects. Additional special collections were also considered for deacidification in consultation with curators and selectors, including the Darwin Collection, Japanese war crimes documents, and a routine system of deacidifying all new geology maps.


In spite of the administrative problem inherited with the Deacidification Unit, we went full steam ahead with production innovations. Switching to the newly available Soft Spray system increased our productivity tremendously, and saved tire and expensive cleanup chemicals. We reorganized workflows and operator schedules to optimize comfort, safety, and productivity, and to alleviate boredom. The changes paid off. In our first year, 1985-86, we deacidified 257,204 pages at a unit cost of $.03/page (chemicals and labor only), improving production by more than 73% and reducing the cost per page significantly. These results were achieved in only one work day a week with two operators, in contrast to the full-time five-operator schedule of 1983-84. It is important to note that we got these results not just through technological advances, but through making work more engaging. Student workers were encouraged to bring in music, work two at a tire in a it buddy system, and take on responsibility as shift "captains.

Administrative Concerns

We solved the problem of how to deacidify large numbers of materials at a low unit cost; however, what do deacidify remains a concern. We adhere to the premise that deacidifying new materials is the best use of the treatment, yet identifying these candidates is a time-consuming, costly process of pretesting and evaluation. Wei T'o solution is not suitable for many papers, and while experienced conservators know which general testing to perform for deacidification, experience with this particular solution is required to select the appropriate papers for treatment. The original plan (1982) for Princeton was to have a full-time deacidification supervisor to take charge of all this testing and decision-making, as well as to oversee the management of equipment, chemicals, and operators. This never materialized after the initial project, unfortunately. In addition, the Library's priority focused more and more on binding, and less on conservation, and the deacidification lab was used as a storage room for the growing Prebindery backlog. This loss of space, staff, and priority forced us to downscale our operation, arid, in combination with other concerns, finally to stop altogether.

Wei T'o Technology

Some limitations of Wei T'o as a deacidifying agent surfaced in our research and experience. There is no independent testing or research on the product, so the conservation community has had to rely on data from Wei T'o Associates, Inc. We discovered problems, and benefits, through our own experience and through conferences with other conservators, scientists, and preservation administrators. Since we had "scaled up" the usual spray booth and single gun to a system with five booths, we ran into more problem than a smaller lab would normally encounter. While there is much discussion at conferences about the pros and cons of Wei T'o products, I can only report on our own findings here at Princeton. 1) Wei T'o solution raises the pH of paper very high, usually to 9-10 immediately after treatment, dropping slightly within 24 hours. 2) Wei T'o solution is not suitable for many papers, among them coated, colored and lignin-containing papers. (Coated paper will stick together and many colored papers will change color or darken.) 3) Wei T'o Soft Spray is 92% Freon, which raises serious environmental considerations about emitting harmful CFCs into the atmosphere. (Union Carbide claims that a Freon substitute is on the horizon.) 4) Leather, cloth and other materials must be carefully masked before treatment.

In my opinion, Wei T'o Associates should offer more information to clients about pretesting, potential problem, ventilation standards, gun and line maintenance, and basic paper conservation information. The only way to assure the correct use of Wei T'o is to have expert staff on hand.

1989 Research Project

In July 1989 we began a project to test a single of the total item deacidified during the past six years. We chose books from the first two Rare Book projects (Holden and Edwardian Novels), and items from the Mudd Archives, Fine Hall (Math/Physics) Library, and Firestone Library stacks. The sample represents roughly 8% of the total item treated, and is drawn from a wide range of papers--modern to 17th century, wood-pulp machine-made to pure cotton handmade.

After selecting the items to test, from a wide range of paper types, we took two surface pH readings of each item with ColorpHast pH strips. Due to funding, time and equipment constraints, no mechanical, physical, or other testing was done. Wherever possible, we tested untreated volumes (in a serial run) as controls.

Table 1. pH of Princeton Books Deacidified 1982-89 (Sample)

Treated Volumes




pH Range



pH Range








Edwardian Novel







Firestone serials







Fine Hall







Mudd Archives








The deacidified pages are not uniformly alkaline, but their pH averages close to 3 pH points higher than controls. Table 1 shows the average and range of pH for treated and control books, and indicates that Wei T'o is an effective deacidifying agent for a wide range of papers. The discoloration of newsprint that can occur during treatment did not significantly worsen over the period since treatment. Test data for each volume tested are available through the Abbey Newsletter office.


Large-scale deacidification programs are complex because they involve technological, organizational, and logistical problems. At Princeton, there are further complexities because we tried to do something no one had done before. We chose a proven technological process, used with success by many labs, but increased the scale and scope of our system fivefold. Technology, however, is only one issue, as the application of a chemical process has no relation to the greater problems of funding, staffing, and institutional priorities.

Our laboratory, designed by Robert Parliament, will have an extraordinary state-of-the-art ventilation system, permitting the safe use of spray apparatus. The velocity is adjustable, and we have even made use of the large screen spray area as an effective suction table an occasion.

The new Preservation Officer and conservators will have the immediate charge of assessing the future of our deacidification program. After six years' experience, we have had a significant impact on the field of large-scale deacidification. With this report, I hope to help other institutions to ask the right questions before embarking on large projects. We all move ahead through this dissemination of research and knowledge. I hope that others will be inspired to share their own experiences with deacidification projects, both positive and negative.

I would like to thank Sandi Milburn, Senior Preservation Specialist, for editorial and research assistance. Kevin Shopland, Senior Preservation Specialist (1986-89), assisted in the 1989 research project, organizing test item and compiling data. Finally, I would like to thank Robert Parliament for his contributions to this report.

1 letter from Robert Parliament, March 31, 1990.

2 Idem

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