The History of Archival Boards in the U.S.A.
and MicroChamber Technology
The first attempt at producing an archival board for preservation housings in North America was made in the 1960s. This first boxboard, gray with a red pulpy center and a pH of 6.5 was considered to be at the leading edge of archival storage technology. Information that acids were the root cause of paper deterioration was beginning to be widely disseminated among those concerned with preserving documents, books and works of art on paper. By todays standards, this mildly acidic board would be unacceptable for use as a preservation housing; however, at the time, its production was quite an achievement. The board mills of this era all utilized acid paper making systems, and even this mildly elevated pH level caused severe problems for the mill which produced it.
This was the period when Frazer Poole was beginning to lead the US Library of Congress preservation program into new areas. The Library quickly established new standards which required a pH of 8.5 for preservation housing boards. The paper adapted for this purpose was an unbleached (therefore brown) kraft. It retained its full complement of lignin, and no alkaline buffer was added. Unfortunately it did not retain its alkaline pH for long. The solution to this problem was thought to be the addition of calcium carbonate as an alkaline buffer. However, as time passed, it became apparent that the addition of alkaline reserve did not prevent the pH from dropping into the acidic range in boards containing lignin.
Further progress was made in 1979 when Conservation Resources introduced the first gray boards made with quite low levels of lignin and alkaline buffering distributed evenly throughout the entire board. In 1980 another advance was made Conservation Resources introduced the first lignin-free and sulfur-free alkaline buffered board, produced initially for the Library of Congress.
The goal, until very recently, was to produce stable archival papers and boards which would not break down and contribute to the deterioration of the collection housed within them. With the removal of lignin and other substances which promoted further deterioration, and with the inclusion of alkaline reserve throughout the board, we thought we had achieved the ultimate in archival storage housings: a truly non-reactive housing that met our passive preservation goals. However, as observational and experimental knowledge increased, it became apparent we needed to find additional methods of dealing with the shortcomings of contemporary archival alkaline buffered preservation materials.