In 1934, B.W. Scribner of the National Bureau of Standards published a long article in the Library Quarterly, reporting the Bureau's recent research on methods of preserving books and newspapers. Most of the standard aspects of preservation were covered--temperature, humidity, light, particulate and pollution control--although they sound quaint to us today. (For instance, a maximum relative humidity of 80% was recommended; today we know that anything above 65% is an invitation to mold growth.)
The article devotes two pages to "Quality of Paper," describing two studies by the Bureau, the first of which concerned the influence of different kinds of fibers on the aging qualities of papers, involving over 300 old books and newspapers from 1830 to about 1900. The first page of that section is reproduced below, because it gives the dates of introduction of mechanical and chemical wood pulp. Results agree closely with those of the Barrow Lab, reported in Strength and Other Characteristics of Book Papers 1800-1899 (Permanence and Durability of the Book, 5), a larger study published in 1967.
Quality of Paper
As the present types of record papers have not been in existence for more than 25 to 100 years, the time varying with the kind of papers, the relative permanence of the better grades as compared with the old hand-made papers still remains to be found by further experience with them. To obtain information on the influence of the different kinds of fibers on the aging qualities of papers, and to define the time periods covering transitions in fiber usage, paper from over 300 old books and newspapers were examined for their condition as related to the kinds of fibers present. The specimens covered quite thoroughly the transitions in paper-making practices from about 1830 to the full development of the modern types of papers and their use about 1900. The papers ranged in condition from those showing little or no evidence of discoloration or brittleness to others which exhibited a dark, brown color and broke readily when creased.
The fiber analyses of these old papers indicated very similar usage in the past of the different kinds of fibers for newspapers and books. Rag fibers were found exclusively until 1868, when the first straw fibers were found, followed by ground wood in 1869 and chemical wood in 1870. From 1867 [sic] to 1895 the newspapers and many of the book papers were composed of various mixtures of rag, straw, chemical wood, and ground-wood fibers. Apparently the present type of newsprint paper, which is composed of a mixture of unbleached chemical-wood fibers (sulphite) and ground-wood fibers, became well established by 1895. Ground wood was found extensively in book papers until 1904. Since that time the book papers have generally been composed of bleached chemical wood and rag fibers, alone or in mixture. The papers composed of rag fibers were nearly all in excellent condition, and those containing straw and chemical wood fibers, or mixtures of these with rag, were mainly in good condition. On the contrary, nearly all the papers which contained ground wood in appreciable quantity were badly deteriorated. The only important class of record paper in which ground wood is still used is newsprint, and the librarian knows from bitter experience how difficult it is to preserve newspapers. Fortunately, the New York Times initiated in 1927 the practice of printing library editions on high-grade paper, and this innovation has been followed by other publishers.