Paper is an organic man-made material composed of fibres from various sources. Plant fibres which have traditionally been used for paper-making include cotton, hemp, linen and, in the case of Asian papers, rice, bamboo and mulberry. Modern papers tend to be produced using wood pulp, creating a generally lower grade product.
It is commonly accepted that paper was invented in China as early as the second or first centuries BC and that it spread westwards on the Silk Road. Khotan became a centre for paper-making and, from the eighth-century, paper-making was known in the Arab caliphate with Chinese paper-makers at Samarkand. It was, however, several centuries before paper-making spread to Europe via the Arabs.
A large proportion of manuscripts from the Eastern Silk Road are paper-based, with paper being brought from Central China and also made locally. Papers produced from traditional plant fibres have better preservation properties and tend to survive longer and in better condition than modern papers. Thus many of the paper documents from this region are in excellent condition.
Paper and Ink Analysis
Paper analysis is a specialized investigative process aimed at extracting historical and physical evidence from paper-based objects.
Scientists and researchers have a number of analytical tools at their disposal, ranging from standard optical magnification, to more sophisticated techniques. These tools are used, alone or in combination, to characterize the properties of paper in a number of ways. Qualitative analysis is used to determine the material composition of the paper or media; quantitative analysis measures the quantities of each component. A chemical analysis can be used to evaluate, for example, the composition and pH (acidity) of the paper, whereas the physical analysis of the object can be used to measure strength or colour. Clues collected by paper analysis can be combined and interpreted to build up a picture on the history, origin and age of an object.
IDP has worked in cooperation with various researchers and institutions to promote the study and understanding of the cultural material found on the Silk Road. In particular, the analysis of fibres from paper and textile objects has been the subject of an ongoing project involving historians, scientists and researchers from different countries (see conservation projects). Reports and findings from the projects have been published by IDP in its newsletter, in dedicated publications and now on this website. IDP is creating a database of Asian historic paper fibres complete with images.
There are several factors that contribute to the deterioration of paper and paper-based objects. Time is any organic material’s worst enemy; its damaging effects can sometimes be slowed down through conservation and preservation practices, but rarely completely stopped. Environmental factors can act as catalysts in the deterioration of paper objects; these include pollution, high temperatures, fluctuating humidity, light and infestation by insects or micro-organisms and generally any extreme condition. Deterioration can also arise simply from poor handling by users or as a result of past conservation treatments which have proved inappropriate and have not stood the test of time.
Paper conservation is the sum of actions performed by professional conservators with the aim of stabilising deterioration and avoiding further damage. While interventive conservation can involve the repair of object, preventive conservation is concerned with the stabilisation of the environment in which objects are kept, and the way they are exhibited and handled.
Some of the most common problems encountered in paper-based collections can be summarised as follows:
- mechanical damage including structural failures, tears, splits, abrasion, creases and folds
- engrained and surface dirt
- biological damage
Papers from Central Asia studied by IDP suffer from most of these, although foxing and insect damage is rare owing to the dry conditions of the desert.
In the attempt to prevent the decay of cultural objects, conservators and preservation professionals have an array of tools. Every treatment decision has to take into account a number of factors before a course of action can be determined. These factors include the condition of the object, the purpose and future use of the object, the historical background and, in the case of culturally sensitive objects, a number of ethical considerations.
Treatments are carried out using the highest quality material and techniques are periodically reviewed to take into account the latest developments in the discipline. Conservators' skills continue to be developed and improved by their participation in training programmes, internships, seminars, conferences etc.
Manuscripts on Paper
A large proportion of the manuscripts on paper from Central Asian collections have received some kind of conservation/restoration treatment at some point in the course of their lives. Unfortunately some of these early experimental treatments, especially the ones carried out before 1970, proved to be damaging to the objects and have accelerated their decay. Where lining was added, the adhesives used had often cross-linked and damaged the paper fibres, causing discolouration, distortions, cracks and losses of media and support. Some objects were lined on both recto and verso with silk gauze. This type of treatment has had the adverse effect of limiting flexibility of movement to the paper and, in addition, the ageing silk has become brittle and embedded into the paper fibres. The adhesive used with the silk lining has also in most cases proved inadequate causing yet more damage to the objects. The modern approach to Central Asian manuscripts does not involve the addition of supports in the form of lining or facings.
Today, conservation treatments carried out on these objects involves:
- Surface cleaning
- Lining removal — when necessary
- Silk removal — when necessary
- Infill of losses
- Tear repairs
- Edge repairs
- Adhesive removal
- Addition of end panels with previously toned paper
- Providing acid free standard rollers to support the scrolls
- Acid free standard boxes for storage
- Some paper manuscripts have only survived as small fragments. These types of material generally only require the minimum of intervention. Re-housing is as crucial for their preservation as it is any other conservation treatments.
Materials used for conservation and preservation of manuscripts on paper include:
- Japanese and Chinese brushes
- Wheat starch paste
- Japanese hand-made paper (various types and thicknesses)
- Acid free tissues
- Paulownia wood boxes
- Acid free rollers
The conservator has to take into account and understand the original format of the object when carrying out conservation. Books from the eastern Silk Road are in many formats, ranging from scrolls and pothi to early examples of codex-style booklets. For a study with examples of these see the Bookbinding pages.
'Textile' is a general term applied to woven objects and fabrics, obtained by the interlacing of yarns using various techniques such as knitting, braiding, looping, lace making and netting. The textile category also includes materials such as felts and non-woven materials in which the fibres create a piece of fabric using different mechanical processes. Fibres used in textile manufacturing can be natural or artificial in origin. Natural fibres include cotton, wool, silk, flax and jute. Starting from the nineteenth century man-made fibres have been developed for the textile industry from polymers such as regenerated cellulose, polycaprolactam, and polyethylene terephthalate, which have become familiar household materials under the trade names rayon, nylon etc.
Textiles, like paper, are very vulnerable to damp conditions. However, the desert conditions of eastern Central Asia aided their preservation and many textiles have been recovered from Dunhuang and archaeological sites, with some examples in an excellent condition. These are a rich resource for textile historians as they shown a great variety of simple and complex weaves and designs. It is important that they are conserved in a manner which allows the scholar to obtain information on the materials, weaves and pigments.For an overview of the conservation of textiles from Dunhuang and other sites see The Stein Mellon Textile Project at the V&A and for details of their storage solutions see Storage of the Stein Loan Collection.
Object conservators are responsible for the care and maintenance of 3D objects in their collections. Unlike other specialisations within conservation, object conservators look after objects made from a diverse range of organic and inorganic materials, such as stone, metal, glass and ceramics, as well as plant, animal and synthetic materials.
Among the items excavated from eastern Central Asian sites are numerous objects made from stucco, clay, wood, plant fibres and metal (including caches of coins).
The work undertaken within this branch of conservation involves the examination and treatment of objects of a very diverse nature. Some objects may still have a functional purpose as in the case of furniture so this type of conservation requires a flexible approach to common problems. As with other specialisms, examination, photography and documentation of each object is carried out prior to any treatment in order to establish a comprehensive record of its condition.
Cleaning is the most commonly performed treatment on objects; surface dust can be removed with a soft brush or using specially adapted vacuum cleaners set on a low vacuum suction. Ingrained dirt in an object’s surface can be cleaned either by using cotton swabs and solvents, or by using a procedure involving applying to the surface a poultice made up of various chemicals to aid the removal of stains or dirt. The wide range of materials involved in object conservation precludes the use of standard treatments. There are some treatments that are carried more frequently than others; for example, the consolidation of a damaged paint layer or the repair of broken or cracked objects.
Wall Painting conservation
There are many sites in eastern Central Asia containing wall paintings, most especially in Buddhist cave complexes such as Dunhuang, Kizil, Bezeklik etc. Many paintings remain in situ while others have been removed to institutions worldwide. For further details of wall painting conservation at Dunhuang see the Getty Conservation Institute site. For an example of a painting from Bezeklik conserved at the Hermitage in St. Petersburg see the Hermitage site.
Preservation of digital data is a key concern of IDP. For issues concerning digital preservation and external links see the British Library's Digital Preservation pages.
Conservation and Digitisation
IDP was started to address the seemingly opposing aims of enabling much wider access to the Central Asian collections while ensuring their long-term preservation. Given that handling of the originals is one of the greatest threats to their preservation, meeting both aims has posed a dilemma for the holding institutions. The production of surrogates, microfilms for the manuscripts and photographs of objects followed by publications of catalogues with images, was only a partial solution. Microfilms are generally held by institutions, so only provide limited access, and are usually black and white. Facsimile publications, especially of very large collections, are expensive, impractical and, again, only offer limited additional access. The arrival of the broadband internet and the technology to produce high-quality digital images changed this situation. IDP immediately took advantage of this.
Digitisation therefore, as well as a means to greater access, is also an aid to conservation as it can reduce handing of the originals. But against this must be measured the possible adverse effects on the object of the handling and the exposure to light required for the digitisation. IDP takes these issues very seriously. It carries out a conservation assessment of each item before it is passed for digitisation. Handling and exposure to light during digitisation are kept to a minimum. Only cold light sources are used. The objects are photographed using specially designed stands and cradles to avoid any pressure which might harm them. These methods are assessed and adjusted, where necessary, for new types of objects before photography. IDP photographers are all trained in the handling of objects and work closely with conservators and curators.
This bespoke digitisation is essential when digitising heritage material. While it makes digitisation more costly in the short term, it can be argued that it saves costs in the long term by avoiding any costly conservation treatments following digitisation and producing the best image possible so reducing the need for expensive redigitisation.