Provides results of a study on deacidification and lamination with cellulose acetate film and tissue of naturally aged laminates and their components. The folding endurance of the older films exhibits approximately the same values as did that of four new films tested in 1940 and several modern films. Likewise, the folding endurance of the recast films of the early laminates compares favorably with that of recent laminates. The low pH of the films purchased during the first 3 years of operation apparently did not lower their folding en durance. A small chemical change is believed to be taking place because of high acidity. Good progress has been made, however, in the development of the deacidification process for the laminates so affected. According to the pH values, the older documents are believed to have a high rate of deterioration. After the development of deacidification in 1940, a decided improvement followed during the next 4 years. Since 1944 further improvement points to a near neutral condition and a very slow rate of deterioration. The pH of the early tissue was lower than desirable, and, no doubt, a loss of strength re sulted. Since 1944 the pH of the tissue is near neutral, and it is believed to have a very slow rate of deterioration. Occasionally, restored documents (one or two per year of the many thousands laminated since 1938) are returned to the writer's shop for repairs. In nearly all cases they have become accidentally torn, but none have shown signs of embrittlement caused by deterioration of the film or tissue. In a recent case, three one-section books exhibited failures along the sewed edges (creased) after 25 years of use and with an estimated 1, 250 (based on recent requests) borrowings. The test data indicated that there was no evidence of embrittlement but that there was some depletion of strength due to wear. Much stronger margins were later developed assuring greater potential use for the more recent laminates. During the past three decades very worthwhile improvements were made in the development of restoration processes. Finding the presence of acidity in deteriorated documents and the necessity for eliminating it from all components of the laminate is particuarly noteworthy. The test data and examinations of the early films and laminates show no evidence of failure due to embrittlement. While these laminates are expected to give good service for a number of years to come, those embodying the later improvements are expected to have greater use and longevity. As with many other processes, appropriate investigations in the future should provide con tinued improvements in a well-established and satisfactory method of -- AATA