Library Material Conservation
Library Material Conservation the process used for preventing damage or destruction of the library materials, ie manuscripts, publication and other materials for reading, study or reference books, etc. Libraries in ancient Bengal had manuscripts made of palm leaf, taret leaf, bark and Bhurjapatra before the advent of paper and were able to satisfy the readers of that time. When the traditional hand made papers began to be used as writing materials, paper manuscripts, miniature paintings, documents and deeds entered into libraries until the middle of 17th century. The chief ingredient of these materials is cellulose which is very much sensitive to light, heat and humidity and the materials are vulnerable to fungi, worms, beetles and insects.
Moreover, they become damp at high humidity of atmosphere. The librarians of ancient period used to expose the manuscripts and other materials to direct sun light for removing dampness, destroying fungus, worm, beetle and insect. As an insect repellent, they used to hang Nim leaves with small branch in the library and sometimes kalizira (black cumin) into a small cloth bags were kept in bookshelves, or boxes on the same occasion. Some manuscripts were warped with red cloth (Lal shalu) perhaps in view of keeping them safe, repelling insect and religious nobility. Furthermore, manuscript writer put covers on manuscript especially made from the plank of Nim wood to get rid of insects.
From eighteenth century printed books, journals, maps, sanads, documents on various types of paper and microfilms began to enter into libraries after then audio tapes, audio video cassette and cinema films along with the old documents or records started to come to national archives as national asset or heritage. These materials are highly sensitive to heat, light, moisture, atmospheric pollution, acidic gases and were vulnerable to fungi, worms, beetles and insects.
By their prolong effect, these materials become deteriorated resulting black, brown stains, foggy, weak, brittle and acidic nature that tend the materials to damaging condition. The relative humidity and temperature in the library will always be kept within 60% and 20'C. This can be done with air conditioning system. Most of the libraries of Bangladesh can not afford this system. In the big libraries like the university libraries, public libraries and Bangladesh National Museum library-desired relative humidity is maintained with a low cost machine, dehumidifier. The temperature is reduced with operating requisite number of electric fans. Naphthalene is used as insect repellent and spread among the books, journals, and manuscripts, paintings and documents.
The chief component of palm leaf, taret leaf, Bhurjapatra, paper and audio, video tape is cellulose, so the library materials made of above have been treated in the following modern methods originated from Europe:
Fumigation an essential treatment for all types of library materials that can remove fungus, worm and beetle affected materials. The technique of fumigation needs a wooden chamber in which some wire net-shelves contain library materials with especial arrangement and fumigant thymol into dishes are kept on the two 60 watt bulbs through the holes made for this purpose, of two sides of lower self. These bulbs are to be 'ON' for two to three hours daily and that will be continued seven to fifteen days for completing the fumigation period. After then the materials are taken away, cleaned and transferred to safe place. Vacuum fumigation in a metallic chamber with para dichlorobenzene as fumigant is also used. Dhaka University library, public library and Bangladesh National Museum library have the thymol fumigation chamber. Besides thymol, there are some lethal fumigant which are paradichlorobenzene, ethylene oxide, carbon disulphide etc.
Cleaning Second step of preservation treatment is cleaning which are (a) physical cleaning, and (b) chemical cleaning. There are two-type chemical cleaning that includes (a) aqueous washing and (b) non-aqueous washing.
Physical method In physical method of cleaning, the superficial dust and soots of library area are cleaned by sweeping and that on cellulosic materials are removed with the help of cloth duster, soft hair brushes, and occasionally with dust cleaner.
Fixing ink Writing ink and some dyes on paper and textile materials are fusible in water or organic solvents. Before washing those are fixed with soluble nylon in methanol or PVA (poly vinyl acetate) in toluene.
Non-aqueous washing means the washing of materials without water. The badly degraded scripts on paper and textile materials, where is a possibility of damage in contact with water are selected for non-aqueous washing. It is done with organic solvents like methanol, petroleum, dichloroethane, diacetone alcohol.
Restoration treatment There are so many restoration treatments for cellulosic materials which are pasting, lamination, mending, patching, lining, trip-lining, sizing, consolidation and impregnation.
Lamination One of the popular restoration treatment for paper materials in Bangladesh. There are two types of lamination which are: (i) Solvent lamination (ii). Heat lamination. Conservation scientists of Bangladesh National Museum prefer solvent lamination but those of Archaeological Conservation Laboratory choose heat lamination. In the solvent lamination the deacidified torn or brittle paper is sand witched with two-ply cellulose acetate thin film and then two ply acid free tissue papers. The cellulose acetate films of both sides are dissolved by applying acetone with the help of cotton swab and mild hand pressure. As a result paper becomes semi-plastic and free from danger. In heat lamination technique, paper is also sand witched with only two ply cellulose acetate films and passed into the lamination machine at 100'C temperature for one minute which makes the paper semi-plastic. Both the laminations have drastic effect on paper due to decomposition of cellulose acetate films and acidic reaction, now being discarded from the developed country in the world. [Md Saber Ali]