Background: Some documents are highly susceptible to embrittlement, which can make those documents unusable. Some documents that have acidic paper are susceptible to turning brittle and unusable over time. The chemistry of this is complex, and acid components may come from fiber stock (such as ground wood pulp) or additives (such as bleach or alum rosin size). Once paper is weakened, though, little can be done to restore its original usability. Good preservation practice is to prevent this decay before papers become fragile. Research has shown that adding alkaline compounds to acidic paper (in a process called deacidification) before embrittlement begins, can extend the life expectancy of these papers. Environmental controls for temperature and humidity are the simplest method, applicable at large scale and for the widest array of materials, but may not be practical in all situations. The Library of Congress has been involved in several projects to develop and employ mass deacidification methods for appropriate materials.
More about Mass Deacidification
Contributing Studies: See the following
Library of Congress Technical Specifications for Mass Deacidification. 2004.
[PDF: 5.03 MB / 115 p.]
Technology Helps Library Save its Paper Collection. April 1997.
Mass Deacidification Report: Bookkeeper Process Evaluation. September 1994. [PDF: 191 KB / 29 p.]
Project Description: Over several decades, various mass deacidification reagents, compounds and procedures were tested by the Library of Congress. This has led to the use of a magnesium oxide procedure that has been tested, evaluated, and implemented to treat approximately 5.5 million books and a selection of manuscript materials at the Library of Congress. (For more information, see Mass Deacidification )
Outcomes:
1. It has been determined that a successful mass deacidification process must:
- raise the pH level of treated paper to a range of 6.8 to 10.4
- achieve a minimum alkaline reserve of 1.5%
- extend the useful life of the test paper (measured by fold endurance after accelerated aging) by over 300%
2. Selection criteria for books and papers to be mass deacidified have been determined.
3. Tracking systems have been developed.
4. Quality Control procedures have been developed.
Update and Images: Through a competitive process, the Library negotiated a fourth contract for mass deacidification in 2005 with Preservation Technologies, Limited Partnership (PTLP) of Pennsylvania. The company is providing book and manuscript preservation services to the Library using the firm's Bookkeeper mass deacidification process. The first contract, in 1995-96, was an R&D process enhancement initiative that enabled the Library to deacidify real Library books for the first time and to resolve book selection, shipping, and quality control details of the deacidification program.
The images below show how books are mounted in vertical treatment cylinders and manuscripts in horizontal cylinders, where magnesium oxide is deposited to neutralize acids in the paper.
Left: Books mounted in treatment cylinders, where magnesium oxide is deposited to neutralize acids in the paper.
Right: Preparing hundreds of manuscript papers for treatment.
