The Paper De-acidification process

The Michigan State University Libraries says before the American civil war paper was made from cotton and linen.  These fibres made a very durable paper, but acquiring the materials and processing them was time consuming and costly.  As the demand for paper increased, a new material and paper making techniques were required to meet the demand.  Wood pulp was the new material and while it met the increase demand for paper, it came a host of problems.  When paper made from wood pulp reacts with heat, light and moisture, acids are formed.  These acids in paper weaken the strength of the paper making the paper turn yellow, less flexible and becoming brittle.  In this paper the author is going to write on the de-acidification process as a conservation treatment employed to retard or slow down the rate of deterioration.  The author will also try to find if de-acidification is a total solution to paper preservation problems.

Definition of Terms
According to, de-acidification is a process of treating paper documents for the purpose of neutralizing acids within the paper and to create an alkaline buffer.  High acidity levels contribute to the deterioration of paper, causing yellowing, brittleness, and instability.  Chiwanza and Tsvuura (2011:14) says “de-acidification is the process of removing acids from paper to give a support and prolongs its life span”.  The above authors also say a number of de-acidification procedures have been developed to bring paper from acid state to one of alkalinity.  Alkalinity is the opposite of acidity.  The PH scale reads from 0-14, paper with a PH of 7.0 is neutral.  Values below 7.0 represent increasing acidity.

According to a Technical evaluation Team Report for the preservation directorate, library congress 1994:2-5 the first step in the de-acidification process is the setting up of Technical Evaluation Team.  The duty of the team is to establish the methods to be used and the actual testing of the documents.  The technical evaluation team will make sure that the de-acidification meet laid down standards.  Secondly, the process had to meet specification applicable to process engineering criteria, its ability to be scaled up, and its environmental impact, and health effects.  Thirdly the technical team will consider if library materials or records remain safe and to see if the process could not result in any harmful or unacceptable side effects. After all the above consideration the materials are then tested and selected for de-acidification.

Tsvuura and Chiwanza says there is no single process for de-acidification of paper due to the fact that there are types of de-acidification methods namely, aqueous (water based), non-aqueous (non-water solvent) and vapour.  Chiwanza and Tsvuura say the aqueous de-acidification process involves the immersion of paper document in an aqueous solution or brushing the sheet with an alkaline compound dissolved in water.  The Michigan State University Libraries website suggests that if the pages of a book are particularly dirty, they can be cleaned and washed in a water bath.  The book must first be totally disbound.  Each page is checked for excessive dirt and markings.  These are cleaned off with a soft brush or an acrylic eraser.  Then each leaf is gently placed in the water and left to soak for 15 minutes to one hour.  The water will usually turn (tea colour” as the acids and dirt in the paper is dissolved by water.  A second bath is used to rinse the paper before it is removed to the drying rack.  The last step is to press the paper while it is just slightly damp to flatten it.  Care must be taken on how much pressure is used so as not to flatten the impressions of the printing on the page.  Chiwanza and (Tsvuura 2011:15) says the aqueous treatment is not suitable for items containing water-soluble inks, pigments and dyes, and all media must be tested for solubility before treatment.  The process can only be used safely with printed items.

For the non-aqueous de-acidification the process is as follows:  it involves immersion, brushing or spraying of an alkaline compound dissolved in an organic solvent rather than water, to give the document an alkaline buffer.  Chiwanza and Tsvuura (2011:15) According to cool conservation – aqueous methods cannot be used to treat archival materials in cases in which ink is susceptible to the action of water; therefore, in such cases a non-aqueous method is essential.  The process involves treating the document with a solution prepared by dissolving 19gm of crystalline barium hydroxide octahydrate (BaCOH) 2.8H2O) in one liter of methyl alcohol.  The normal procedure is non-coming led to immerse the document in the solution, but it may be brushed or sprayed on if the document is too fragile for immersion.
While drying any excess borium hydroxide is counted into barium carbonate (BaCO3) by the action of atmospheric carbon dioxide.  Tsvuura and Chiwanza list the advantages of the non-aqueous de-acidification process as, it can often be used on items that cannot be touched by water, the organic solvent do not cockle paper to the extent that water dress and also evaporate much move quickly, and the process is much faster.  If the item is immersed in a non-aqueous bath, some acidic compounds will be washed away, although less than in a water bath.

The vapour phase de-acidification shortened as (VPD) goes as follows according to Harris of Columbia University Libraries is sold either as pellets encased in cheesecloth pouches to be placed in archival storage boxes, or in thin porous envelopes which can be used to interleave a book.  The solid pellets vaporize to permeate the paper with an alkaline gas which neutralizes the acid in the paper.  No buffering are kept in the paper, so there are no long term effects.  Chiwanza and Tsvuura say the vapour phase de-acidification is of most importance for use on bound volumes which do not have to be unbound and to institutions which could not be treated on one-by-one bans.

Collections of libraries and archives are threatened worldwide by paper decay manual de-acidification in a single-leaf process, which is a routine procedure face a constantly mounting problem worldwide that has reached catastrophic and does not present a solution for the preservation of entire collections.  The main problem with paper de-acidification is that it is,, de-acidification is a preventive and not a curative measure i.e. it is most effective when papers are still intact and not brittle.  In some cases paper de-acidification may be too late and the investment in de-acidifying these documents would bring no long-term benefits.  De-acidification could merely “buy precious time” for the preservation of brittle materials.  Therefore de-acidification is not a total solution to paper preservation problem

The author throughout the paper had defined what de-acidification is and explained the aqueous, non aqueous and the vapour based phase de-acidification processes.  Lastly the author had explained that paper de-acidification is not a total solution to paper preservation problem

Chiwanza U.Tsvuura G, 2011, Conservation and reprography, Harare, ZOU
Bluher A, 2000, Experience in paper de-acidification
Ziruch, Swiss National Library
Harris C, 2003, Preservation of paper based materials, mass de-acidification methods and projects, Columbia, Preservation Department Columbia University Libraries downloaded on 23/02/15

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