The Paper De-acidification process
BY ETIWEL MUTERO
Introduction
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 Liswiki.org/wiki/de-acidification, 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 – us.org/don/dt/dt2333.html 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
www.ideas.illinois.edu/bitstream/handle/2142/453/Harripreservation.pdf?sequence=2
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
Conclusion
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
References
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
www.lib.msu.edu/exhibits/sat/cleaning.jsp
downloaded on 23/02/15
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