Paper made of the inner bark of paper mulberry (Broussonetia papyrifera) is employed in conserving various materials from book and paper to three-dimensional organic as well as inorganic objects. Often generically called ‘Japanese paper’, this paper is in fact manufactured widely in the Far East and some areas of South East Asia. The kind of mulberry paper favoured for use by conservators is long-fibred, naturally sun-bleached and un-sized. Its flexibility, modifiability, light weight and long-term stability make it ideal for creating backing and lining repairs, loss compensation, and other types of structural support that are both visually and materially sympathetic to often fragile historical objects.
Mulberry paper is extensively used in the conservation programme for our project in order to stabilise objects with tears, splits and compromised fibre structure. Many of the Pacific barkcloths encountered during the project are of course made from the inner bark of paper mulberry themselves. Therefore, repairs made using the material are often compatible in weight and general texture with the barkcloth objects. This helps us to achieve long-lasting stabilisation through conservation additions as well as helping the repair to blend in nicely for display. Visual sympathy is as important as material stability in such circumstances because the conservation treatment should ideally not be too distracting or dominant to viewers. The paper can also be tinted to match the colour of the barkcloth if required for display.
At the same time, barkcloths and mulberry paper have properties that make them distinct from each other. These differences can be largely attributed to their respective manufacturing methods – barkcloths are beaten, while the paper is macerated and strained. These differences help us easily differentiate the two in close examination so as to avoid confusion between the original material and the conservation addition.
Repair tabs using mulberry paper can be used as a temporary securing solution as well as for permanent repair. Structural repairs are usually applied from the back of the object in order not to disrupt the applied surface. This is illustrated with barkcloth GLAHM E.601 However, in this instance, the feathered edges of the tears prevented making a good alignment of the joins while the strong linear design was very unforgiving of misalignment. To accommodate this, re-moistenable paper tabs impregnated with weak, cellulose-based adhesive were used to align and temporarily secure the joins. After structural stabilisation was carried out from the back, these temporary tabs were removed by dampening them slightly using deionised water. The tabs were safely removed without damaging the fibre structure or leaving visible excess adhesive residue on surface.
Structural stabilisation is one of the key conservation works carried out within our project. Stabilised objects can be safely accessed and handled, so this conservation work expands opportunities for the barkcloth objects to be studied by interested parties and to be displayed effectively for museum visitors.
A vital aspect of conservation is carefully documenting the object before, during and after the conservation work. Such documentation aims to record the individual objects’ physical nature, condition, and any damage to the object resulting from both external and internal factors. Details of any treatment are also recorded, including the materials used for stabilisation and how they were prepared and applied.
Transmitted light, or light shone from beneath the object, is an effective tool in documenting barkcloth. Transmitted light is often used in other disciplines: for instance, documenting watermark on paper and examining structure of substrate in book and paper conservation and locating breakage and cracks in painting conservation. Likewise, transmitted light has played a key role in our work on this project with barkcloth objects. The transmitted light’s ability to illustrate the differential density and structure is very helpful in documenting barkcloth.
Beater marks are one of the most distinctive features in examining Pacific barkcloth. Barkcloth beaters, used to beat the inner bark in order to spread and felt the fibre to produce barkcloth, typically have grooved/carved facets. As a result of beating, the grooved/carved patterns are embossed on the surface of the barkcloth. The fine texture of the beaters mark can be difficult to photograph under normal light. However, transmitted light can be used to show the outlines of the beater marks very clearly
Transmitted light is also very useful in identifying the layered structure of the barkcloth which can consist of several layers.
Structural and physical issues of the cloth can be clearly highlighted by photographing with transmitted light. It is often difficult to visually differentiate between localised soiling and fold marks under normal light.
Structural weakness, such as where the fibre is thinned, split, or perforated, in turn, is difficult to capture by photographing under normal light. Transmitted light helps the conservators identify and map these problematic areas.
The use of transmitted light is an accessible method of documentation that aids visual examination of objects and expands the range of information captured through photography. No technical instrument is necessary other than a camera and a lightbox.