n.the process of applying thin sheets of cellulose acetate to both sides of a document to reinforce it and protect it from the environmentKimberly 1938, 114–115In the event that more extensive treatment is required, documents in the National Archives are generally coated on each side with thin transparent cellulose acetate foil according to a process originally devised by the National Bureau of Standards for the preservation of newsprint. Further research at the National Archives resulted in the adaptation of this “lamination” process for use on all types of paper. This new method is based upon the fact that cellulose acetate foil, being thermoplastic, adheres strongly to paper upon the application of heat and pressure in a hydraulic press.Browne 1953, 223The old Vatican library process of silking manuscripts to preserve them against the ravages of time in the form of moisture or chemical reactions due to the ink or contact with another substance has generally given way to what is called lamination, a distinctly American contribution to archival science. In the lamination process a document is pressed between sheets of cellulose acetate foil while heat and pressure are applied until the substances become in effect blended into one.Turner 1957, 322There seems to be a good deal of confused thinking about the Barrow method as compared with the National Archives process of lamination. . . . The truth of the matter is that there is little similarity between the equipment, the process, or the results of the two methods. The only common feature is that both use cellulose acetate foil.Evans, Harrison, and Thompson 1974, 418BARROW PROCESS. A process of document repair and restoration named after William J. Barrow (1904–67) that involves deacidification, the use of tissue to increase the strength of the original, and thermoplastic lamination.Evans, Harrison, and Thompson 1974, 424LAMINATION. (1) A mechanically assisted process, generally preceded by deacidification, of reinforcing weak or damaged paper documents by enclosing them between two sheets of plastic foil, usually cellulose acetate, and two sheets of tissue which, through the application of heat and pressure, become thermoplastic and impregnate the original. More properly referred to as thermoplastic lamination to distinguish it from hand lamination or commercial and industrial lamination processes. (2) A manual process for protecting or reinforcing a weak or damaged paper document by enclosing it between two sheets of cellulose acetate which are bound to the document by acetate.Woodward 2017, 108Between the 1930s and the 1980s cellulose acetate lamination was a common treatment considered a safe and advisable measure for document conservation. In time, however, archivists and conservators began to notice and acknowledge its destructive effects and after 40 years, they finally put an end to the practice. By then, however, the damage was done. Today, many archives and special collections are burdened with these laminated items.Woodward 2017, 108Basically, lamination involved sandwiching a document between two superheated sheets of cellulose acetate and pressing it so as to attach or melt the plastic to the document surface with the concept being that the lamination strengthened and protected the document.Woodward 2017, 110Cellulose acetate lamination in the 1930s continued a tradition of strengthening documents that began first with silk, in the latter part of the 19th century. The process of laminating with silk, or “silking” continued, albeit limitedly, into the mid-twentieth century. Silk was later supplanted by cellulose tissue, which was also used to “strengthen” documents as a conservation technique. These conservation techniques fell out of favor because silking was expensive, laminating with tissue made the documents difficult to read, and both had a limited life expectancy of 20 to 30 years.
Notes
Lamination was often preceded by deacidification. Lamination is no longer considered appropriate for archival preservation.
