Conservation issues: Brittle books

The term 'brittle book' refers to a book whose pages have become so fragile that they may break, crumble or disintegrate when handled. Deterioration occurs because the paper in the book was made with acidified wood pulp. This process for making paper was popular after the 1850s. Before this time, paper was made from linen and cotton rag and the process was an alkaline one. The acid in the wood pulp leads to decay of the paper, leaving it brittle.

In 1988, Patricia Battin, the President of the Commission on Preservation and Access of the National Endowment for the Humanities testified before the House of Representatives, Subcommittee on Interior and Related Agencies on the severity of the problem of brittle books. She stated:

"...the acid paper on which we have recorded our words and images for the past 150 years is deteriorating at an alarming rate. We face a problem of monumental dimensions. In the area of books alone (the first among several priorities we hope to address in years to come), all indications are that as much as one-fourth of the collections of the nation's major libraries -- including the Library of Congress and the major research and university libraries -- is in a state of serious embrittlement due to the acid paper on which nearly all books have been printed since the mid-nineteenth century. In gross numbers we are talking about 75 million volumes." http://www.nhalliance.org/testimony/1988/88testimony-pbattin.html

She asked for increased funding for preservation and her efforts led to an appropriations bill for fiscal year 1989 that gave the National Endowment for the Humanities $12.5 million for preservation. Eight million dollars of that went to fund a twenty-year program to microfilm endangered volumes. Some libraries also photocopy brittle books to preserve their contents.

Microfilming and photocopying are not the only methods to preserve brittle books. Some books may be so valuable as to warrant deacidification or papersplitting methods of conservation. In the deacidifcation process, conservators treat the paper with a mildly alkaline solution (pH<10) that deposits a carbonate salt into the fiber of the paper. This process does not repair damage done due to brittleness or improve paper that is already brittle. It only prevents further decay of the paper in its current condition, extending its life up to 500 years.

Below is a simple procedure for deacidifying paper:

Materials:
Calcium chloride (CaCl2) solution (saturated)
Sodium carbonate (Na2CO3) solution (saturated)
3 shallow trays or pans
acidic paper (several numbered samples)
pH pens

Procedure:
1. Test paper samples with pH pen. Record the pH as well as the number of each sample.
2. Choose one of the samples that tests acidic and mass on centigram balance. Record sample number and mass.
3. Submerge the paper sample in the shallow pan filled with calcium chloride solution until it is completely soaked through. Carefully remove and dry. You may use a hair dryer or blower but NO HEAT!
4. Place the dried paper sample into a shallow pan filled with sodium carbonate solution and allow to react completely (5-10 minutes). Remove carefully and dry. Again you may mechanically dry with NO HEAT.
5. Thoroughly wash the paper with water. This will require several washings!
6. Dry paper and mass on centigram balance.
7. Test paper with pH pen. Record.
8. Determine the % calcium carbonate in the deacidified sample.
(from http://web2.ccpl.org/prvEmployees/HTML/scienceproject/OnlineExhibits/ncw/Deacidification%20.html)

In January 1995, Congress authorized a two-year, $2 million Library of Congress Mass Deacidification Project to treat LoC 72,000 books. The process, known as the Bookkeeper process, impregnates paper with magnesium oxide particles that neutralize the acid in paper and leave an alkaline buffer behind. This process was an offshoot of the Library's 20-year effort to develop and refine another deacidification technology known as the diethyl zinc gaseous process.

For paper that is already too brittle to be helped by deacidification and even too brittle to be microfilmed or photocopied safely, institutes such as the Folger Shakespeare Library and the Library of Congress use another process called papersplitting. The LoC website describes this process saying, "In this process the brittle paper sheet is "sandwiched" by temporarily adhering two support papers, one on each side. Pulling apart the support papers splits the original paper. A new "core" paper can now be inserted between the original paper halves and the entire package is reassembled. The support layers can be removed in an enzyme bath and the original paper and inserted core paper are pressed and dried. Since washing and deacidification of the original paper is an integral part of the process, both the physical and chemical condition of the paper is improved." (from: http://www.loc.gov/loc/lcib/970421/deacid.html)

The Folger Shakespeare library describes it saying, "To prepare for paper splitting, support sheets are adhered to both sides of the paper with a gelatin adhesive. After the glue has set, but while the core of the paper is still moist, the support sheets can then be carefully pulled apart, splitting the core of the paper. Following this delicate process, the two halves of the paper are dried and reassembled with a sheet of Japanese paper sandwiched between them. The Japanese paper at the core is attached with an adhesive that is soluble only in cold water. After it dries, the support sheets can be removed in a bath of very hot water, dissolving the gelatin adhesive, but not the core adhesive." (from: http://www.folger.edu/template.cfm?cid=888)

Here are some images of the process from the Folger Shakespeare Library:








Both deacidification and papersplitting are time consuming, technically exacting and expensive processes. Frankly, so is reformatting brittle books via microfilming or photocopying. Thus, the danger to valuable collection items is still great since most libraries do not have either the personnel or financial resources to save their collections.

Ashburn, Norma L. (2001). Deacidification of Valuable Papers. Available
http://web2.ccpl.org/prvEmployees/HTML/scienceproject/OnlineExhibits/ncw/Deacidification%20.html

http://www.nhalliance.org/testimony/1988/88testimony-pbattin.html

Kelley, George B. (1989). Practical Aspects of Deacidification: pH and Alkaline Reserve. Alkaline Paper Advocate. 2(1). Available
http://palimpsest.stanford.edu/byorg/abbey/ap/ap02/ap02-1/ap02-111.html

Dalrymple, Will. (1997). A Paper Chase: Technology Helps Library Save its Paper Collections. Library of Congress Information Bulletin. Available
http://www.loc.gov/loc/lcib/970421/deacid.html

Library of Congress. (2006). MDEP Paper Strengthening Pilot Program. Available
http://www.loc.gov/preserv/papertreng.html

Folger Shakespeare Library. Paper Splitting and the Trevelyon Manuscript. Available http://www.folger.edu/template.cfm?cid=888