Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Reexamination Certificate
2001-03-02
2003-11-04
Zacharia, Ramsey (Department: 1731)
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
C428S035700, C428S413000, C428S447000, C428S480000, C428S522000, C428S523000, C206S205000, C422S040000
Reexamination Certificate
active
06641877
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an article for retarding the deterioration rate of acidic paper and a method of use thereof. In particular, the present invention relates to an article capable of enclosing an acidic paper and having a reservoir of a deacidifying agent for retarding the deterioration rate of the acidic paper and method of use thereof.
2. Description of the Related Art
Paper, of course, is an inexpensive material used for a wide range of products, most of which are discarded after use. The vast majority of paper products are destroyed or recycled within a decade of manufacture. On the other hand, there are innumerable items of value which are also made of, or on, paper. These include critical documents, art prints, original drawings, limited edition books, etc. Usually many of these items are already quite old when the need for preservation is recognized. In general so many paper items are destroyed that the survivors often become collectible after a period of time. The time for an item to be considered collectible, or otherwise merit preservation, varies, of course, depending on the particular item, but most commonly falls between 20 and 100 years. Some items have historical or artistic value from the moment of their creation, but most items are already slightly deteriorated when preservation becomes a goal.
Paper dates back to the second century AD when it was invented in China. Prior to then books, documents, etc. were printed primarily on parchment or vellum. The Arabs began using rags as the cellulose fiber source for paper, and rags remained the primary fiber source when paper making was introduced into Europe by the Moors in the 1100s. Initially most rags were linen, but later cotton came into common use. Rags continued to be the principal fiber source until the early 1850s, when the demand for paper had reached such heights, that the supply of rags was insufficient to produce paper in the quantity needed. A paper manufacturer in New England had even resorted to using linen-wrapped mummies from Egypt as a fiber source for certain papers. Around 1850 wood fiber began to replace rags as the cellulose fiber source. Paper manufacture underwent a dramatic change using chemical, then mechanical, pulping processes to convert wood fiber into paper. After the commercial introduction of a mechanical process for ground wood pulp in 1867, almost all paper contained wood pulp in at least some proportion. Although these changes enabled paper manufacturing to meet the ever increasing demands for paper, the changes resulted in a significant increase in the rate of paper deterioration upon aging. The lignin in wood pulp papers forms acid upon aging, and acid catalyzed hydrolysis is the principal mechanism for cellulose degradation and consequent strength loss. Many of the other changes that had been occurring in paper making since the 17th century had also resulted in increased acid in the paper. One such example is the use of alum-rosin sizing which has been a common practice since the early 1800s. The consequence is that many of the books printed in the late 1800s and early 1900s are in worse condition from the paper standpoint than books printed in the 1600s. Many newspapers and paperback novels printed as recently as the 1930s are now almost unreadable due to the advanced state of paper deterioration. It has been reported in “The Self-Destructing Book”, by John Dean,
Encyclopedia Britannica: Yearbook of Science and the Future,
1989, that up to 25% of the books in the Library of Congress collection already are deteriorated to the point that their use is affected. Newspapers, of course, are an example of paper that deteriorates very rapidly. Most newspapers show significant embrittlement and discoloration after a single decade, or even after a few weeks if kept in a warm environment or exposed to light. High humidity can also accelerate the deterioration rate (“Artificially Accelerated Aging of Paper”, by R. R. Yabrova, in
Collection of Materials on the Preservation of Library Resources
, Israel Program for Scientific Translations).
The biggest enemy of paper is the acid formation prevalent in most papers produced after the 1850s. Although the use of alkaline paper is increasing, even today most paper is still acidic. The rates of acid deterioration, as well as other mechanisms of chemical deterioration, are accelerated by heat; and, unfortunately, normal warm ambient temperatures are sufficient to accelerate the deterioration significantly. If it needs to be readily accessible, paper should be stored between 68 and 70 degrees Fahrenheit with a relative humidity between 45 and 50 percent (“The Self-Destructing Book”, by John Dean,
Encyclopedia Britannica: Yearbook of Science and the Future,
1989). If frequently handled, lower temperature and humidity are not considered ideal, even though most chemical deterioration mechanisms are further slowed, because excessive loss of moisture from the cellulose fibers causes the papers to become brittle. On the other hand, if storage is to be over long periods without disturbance, then lower temperature and humidity conditions are preferred (“Newsprint and Its Preservation”, Preservation leaflet No. 5, Library of Congress, 1981;
Preserving Library Materials, A Manual
, by Susan G. Swartzburg, The Scarecrow Press, 1995). Heat, and light (particularly UV), are paper's major enemies. Other causes of deterioration include insects, rodents, water, mold (primarily mildew), and air pollutants, besides the obvious wear from handling or use.
Air pollutants can contribute very significantly to paper deterioration, particularly in industrial and urban areas of developing countries (“Paper and Its Preservation”, Preservation Leaflet No. 2, Library of Congress, 1983 (revised)). Even in a home environment, however, air pollutants can have a significant impact on paper discoloration and deterioration. In one observed case a newspaper sheet dating from the 1700s, which well predated the manufacture of acidic paper, was stored in a drawer that was closed (dark) 99+% of the time. On top of the paper a narrow strip of sheet metal happened to be lying across the paper. The metal strip laid undisturbed on the paper for about 10 years. The paper directly under the metal strip was noticeably lighter in color, and it appeared somewhat less embrittled than the remaining area, after the 10 year period, even though the metal was only lying on the paper surface. Although in the dark, the paper was exposed to the atmosphere, and the room was located over a kitchen. The room also got quite warm during the summer months. The paper exposed to the atmospheric pollutants, presumably from the kitchen, or a cat litter box which was located in the same room, discolored and deteriorated more during this 10 year period than it had during the previous 200 years; moreover, something as simple as a metal strip lying on the surface significantly changed the deterioration rate.
Air pollutants, water, rodents, mold, and light are external enemies of paper. These contributors to deterioration can in general all be reduced by enclosing the paper article in a protective encasement. Acid deterioration, on the other hand, is inherent in most papers from the time of manufacture. In fact, air tight enclosure of acidic papers can actually speed the deterioration rate (“Paper: Manuscripts, Documents, Printed Sheets, and Works of Art”, by Karl Buchberg, in
Conservation in the Library
, edited by Susan Garretson Swartzburg, Greenwood Press, 1983).
Although even under ideal conditions all paper will deteriorate slowly by oxidation, non-acidic papers can last centuries with no significant observable change. Acidic papers, however, seldom last more than a decade before some change in appearance and properties are readily observable. Most preservation techniques for these papers include a deacidification step. A minimum pH of 6 is sufficient to effect a significant reduction in the rate of acid hydrolysis of cellulose, b
Nixon & Peabody LLP
Zacharia Ramsey
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