n.a preservation technique intended to increase the longevity of paper documents by raising the pH to at least 7.0, and often including the deposit of an alkaline bufferTurner 1957, 325There is one other major difference between the [William J.] Barrow and the National Archives processes. Barrow insists that papers to be restored should be deacidified. The actual method of deacidification also has the effect of flattening as well as cleaning the document. While deacidification is a great contribution to the science of document preservation, it is considered that sufficient time has not elapsed for the absence of deacidification to be the cause of the deterioration of restored documents in the National Archives.Barrow 1965, 286In 1939 deteriorated sheets needing restoration were found to be highly acid. By mid-1940 a deacidification process, consisting of soaking the sheets in a solution of calcium bicarbonate, was developed and used before lamination. Improvements in this process were made in the mid-1940’s by soaking in both calcium hydroxide and calcium bicarbonate solutions. Such deacidification consistently produced a near neutral or mildly alkaline condition in the old documents treated.Barrow 1965, 288A much slower rate of deterioration is believed to exist in manuscripts restored the first 4 years after the development of deacidification. A very slow rate probably exists for the old papers deacidified after further improvements were made in the mid-1940’s.Gear 1965, 295–296Deacidification of paper records was first proposed by W. J. Barrow. It can best be described as a process whereby papers with a high acid content are bathed with a mild alkaline solution to neutralize the acid in the paper and protect it against future atmospheric acid. Deacidification is not something that should be done only if one feels like doing it or if one has time to do it. If it is needed, it should always be done.Evans, Harrison, and Thompson 1974, 420DEACIDIFICATION. The process by which the pH of paper documents is raised to a minimum of 7.0 to assist in their preservation. The process is now generally used before documents are thermoplastically laminated.Poole 1976, 157As is well known, there is ample evidence that lamination without deacidification and alkaline buffering is nearly worthless as an archival preservation technique. We consider it absolutely essential, therefore, that all materials to be laminated be deacidified and buffered with an alkaline salt leaving approximately 3 percent reserve in the paper.Poole 1977, 166Neither low temperature storage nor deacidification and alkaline buffering, however, will restore any strength to paper once this has been lost. ¶ At the present time, the most effective deacidification techniques utilize aqueous or solvent-type solutions applied by immersion of the document, or by spraying or brushing. Still needed is a gaseous deacidification method that will make possible the effective treatment of thousands of books and documents simultaneously, without the present inconvenience and high cost of treating each document or each page individually. . . . ¶ Low temperature storage, and deacidification combined with alkaline buffering, provide effective means of arresting the deterioration process and preserving, in their original form, materials which retain some useful life.Cunha 1990, 200Deacidification of already brittle paper is an exercise in futility. Although brittle books and paper records will get no worse after deacidification, they will not improve either, and they are all too often still unusable.Grimard 1994, 675Deacidification—whether of one item at a time or in quantity—is essentially intended to neutralize the acids contained in the paper. From a conceptual point of view, the process seems relatively simple, involving the addition of an alkaline reserve, consisting of calcium or magnesium carbonate, in a way that subsequently neutralizes the deteriorating action of the acids and thus extends the life of the paper significantly.Ritzenthaler 2010, 346–347A number of deacidification procedures have been developed that will bring paper from the acid state to one of alkalinity. Deacidification processes are designed to neutralize the acids present in paper and to deposit an alkaline buffer or reserve that will inhibit its return to the acidic state.Ritzenthaler 2010, 346, fn. 4The term deacidification is commonly used to encompass those processes that neutralize free acids in paper an deposit an alkaline reserve. The terms neutralization and alkalization are more precise and are being used increasingly in the conservation field.Ritzenthaler 2010, 347Deacidification processes are classified according to the method by which the neutralizing and buffering agents are introduced: aqueous (water-based), non-aqueous (non-water solvent), and vapor.Ritzenthaler 2010, 353While deacidification will stabilize and sometimes even improve the appearance of paper records, it cannot restore life to brittle paper. Following deacidification, appropriate methods of support, typically via housings, may be required to render brittle or weak records usable.Phillips 2015, 476While deacidification is a process that effectively neutralizes acids, it does not restore flexibility to paper and, thus, is a procedure best done much earlier in a document’s life. Once brittle, a document will benefit very little from deacidification, and better options would be to reformat the document or to undertake a more intensive treatment.
Notes
Aqueous deacidification uses water as the solvent carrier of the alkaline agent. Nonaqueous deacidification uses organic solvents as the solvent carrier. Vapor phase deacidification involves the interleaving of documents and the pages of volumes with treated sheets that emit an alkaline vapor; now rarely used because it reportedly produces toxic vapors and does not leave an alkaline reserve.
