Apart from carrying out the routine work, a VM team of conservation unit comprising Mr. P.R. Savita and Mr. P.K. Agarwal conducted research in the areas of conservation of manuscripts of paper and it was presented in a national seminar at Vrindavan Research Institute, Vrindavan, (Mathura) held on 29th November - 1st December 2003.

 Rcent trends in conservation of manuscripts of paper
 By V M Team

As is well known conservation of papers involves careful preparation of the conservation statues, fumigation, washing, deacidification and bleaching, mending and lamination - if the paper object is brittle. These processes are in use for long. However, this paper intends to argue that these operational methods need reconsideration for more than one reason. First, the relationship between treatment of paper properties and ageing of paper has to be given appropriate attention. Second, the steps involved in conservation have long-term reactions on physical and chemical properties of all the components of paper including the fibres, fibrils and cellulose polymer chain.

Paper Properties

The paper properties are greatly governed by the manufacturing processes and chemical properties of a paper sheet derived primarily from variables of furnish or pulp components. These variables include the fibre type, pulp stock, refining techniques such as beating or bleaching and compositions including fillers, size, coating and colorants ends. Each (of these) component has different and distinct physical and chemical property, which ultimately finalize behaviour of the paper while interacting with environment. The inherent residual material used may add to deterioration. The environmental factors initiate degradation mechanism like hydrolysis, oxidation, causing brittleness and browning in the paper.

The following processes of treating paper may be critically reviewed as follows:

Washing and Deacidification: Washing in paper conservation, refers to overall treatment of the paper with aqueous solution and most of the time washing is done with distilled water or deionised water. This highly purified water can dissolve the stabilizing magnesium and calcium component of paper. A prevalent notion is that the water supplied by Municipal Corporations contains dissolve salts and should not be used in washing or other relevant treatments in the paper conservation, but normally water supplied by Calcutta Municipal Corporation which is neutral in pH contains dissolved calcium and magnesium along with other ions, those inhibits migration of these ions from paper to washing solution. Use of distilled or deionised water therefore be reconsidered.

Washing and deacidification are the two most fundamentally important stages of paper's conservation. The wet ability of paper is essentially important. Washing with good penetration removes soluble acidity from the paper. Calcium hydroxide and magnesium bicarbonate solutions are mainly employed for the purpose in later stages. The paper object, ink written documents & watercolours on paper are immersed in such solutions. The discoloured solution is replaced and the object is put into fresh deacidifying solution. This normal procedure is easy to use as long as the ink or colours do not bleed in water. But problem arises when modern inks or the colours bleed and dissolve with water treatment. In such cases, the fixation of fugitive colours & ink is essential. This is generally done by applying or spraying 1 or 2% solution of Polyvinyl Acetate (PVA) in toluene. Of late, the use of PVA as fixative has been found undesirable and harmful in the long run. The following facts may be presented this connection.

(1) Polyvinyl Acetate is a polymer of vinyl acetate.

 
 In many years time, the polymer undergoes degradation in presence of light and water, forming acetic acid.

 

 The acetic acid, thus formed, causes damage to the paper objects resulting degradation of cellulose chain.

(2) Application of synthetic polymer will most definitely retard or even prevent the wetting of the paper. So the desired degree of deacidification is not achieved at these places or areas.

(3) The PVA film remains after completion of the washing and deacidification processes. Such objects with thin film of PVA, when subjected to periodic fumigation in thymol chamber or through impregnation, dissolves the resin causing ugly greasy marks (2).

In view of above observations, the use of PVA as fixative should be reconsidered and some other fixative may be discussed.

Bleaching: Bleaching with chemical is a potentially damaging process to the paper and fibres. The Chemical used in the process work either by oxidation or reduction process, reduce the darkening or yellowing of paper, but at the same time also acts on paper fibre and activates bonding. The process may have effects on degree of polymerisation of fibres and ultimately length of fibre may get affected if time period is not controlled. Many paper conservators use sunlight bleaching (3). But this process may also initiate photochemical degradation of paper fibre if the use of UV absorbing sheets are not used for cutting down these high potential radiations. In Victoria Memorial, we follow the practice of sun bleaching process but with the use of UV filters and we are getting good results. The visual effect of sun-bleached paper has a warm white tone rather than bright white tone obtained after bleaching the paper by the use of bleaching chemicals. In our view, the use of sunlight bleaching may be practised and use of chemicals for bleaching should be discarded.

Lamination: For fragile paper objects / manuscripts, general recommendations is to get them laminated by each folio through the use of tissue paper along with the adhesive either using carboxy methyl cellulose / methyl cellulose or cellulose acetate foil. Preferable cellulose acetate foil is recommended and used by well-known laboratories / conservators as adequate transparency is achieved by use of cellulose acetate foil. But at the same time, use of this material as a binder or adhesive should be discarded, as in course of time this material degrades and forms acetic acid/ turns acidic. Findings at Victoria Memorial have proved that the foil turned acidic within a time span of nearly 15 years. Findings in the conservation laboratory; Victoria Memorial are as follows:

 1.  The drawer of the cabinet containing stock of cellulose acetate foil was opened after an interval of about 3 months and it was found that a stinking smell of acetic acid emitted from this drawer. This is a general identification test for acetic acid, as has been told during our studies at lower level.
 2. One sheet of cellulose acetate foil was washed with normal tap water (tested by pH strip and found neutral) for about 15 minutes at normal room conditions and the residual water was collected and tested by pH strips, which contained acidic pH ranging at 6.
3. This water was taken in a test tube and few drops of neutral FeCl3 were poured in it. The blood red colouration was obtained, which is a confirmatory test for acetate ions.
 4. A metal sheet of lead was taken and it was cut into two pieces. Now these pieces were rubbed with emery paper so as to make the half portion shine i.e. unoxidized metal surface was achieved. Now one of these two pieces was put inside the cabinet drawer containing cellulose acetate foils stock and another piece placed on the top of some cabinet box. The drawer was closed as usual. After a period of nearly three weeks the pieces were re-examined. The shining surface of the metal piece was found oxidized and looking dull (whitish grey surface) in comparison with other piece placed at the top, which was still having original shine. Thus it is a clear evidence of action of acetic acid fumes liberated from the stock of cellulose acetate foil.

The effect of degraded verdigris pigment i.e. copper acetate, on ageing is a well established fact but we are still recommending cellulose acetate foil for lamination as we argue that the transparency or visibility of the text retained after its use as adhesive. But we have to rethink about why the use of such material should be encouraged. This may be suitable user friendly or have long life in environment in those countries only, which are producing it, but certainly not in tropical environment like in India. Also the average (more or less) transparency of text is a matter of debate. Therefore, we should not encourage use of such materials.

V. M. Team:
(i) Shri R. P. Savita

(ii) Shri P. K. Agarwal

References:

 (i) Hand outs provided by ICROM in a SPC Course.
 (ii) Same as (i).
 (iii)  The colour reversion of paper after bleaching- Helen D. Burgess - VI-57.
(iv) Alternative to conventional methods of reducing discolouration in works
of art on paper - Keiko Mizushima Keyes - VI - 49.
(v) Recent Scientific research in paper conservation - Dianne Van Der
Reyden.
(vi) Conservation of Library and Archive materials and the graphic arts - Guy Petherbridge.