Conservation of tapestry
Conservation of tapestry
- Ksynia Marko
See also Tapestry
For the purposes of conservation, it is necessary to place tapestries in a category of their own. There are several reasons for this. Tapestries have always been expensive and highly valued, especially since they often incorporate fine silk and metal threads. The skill of manufacture and pictorial subject matter, together with the fact that they were designed by such well-known artists as David Teniers (ii) and William Morris, have given them a cultural significance and monetary value more commonly associated with paintings than with textiles. From a practical point of view, certain characteristics of the tapestry-weaving technique, along with the great size and weight of many hangings, give rise to specific problems that need to be dealt with by specialist conservators. In addition, the space, equipment, and skill required in handling a delicate object that can measure as much as 4–6 m high and 10 m long, and the difficulties of maintaining a consistent standard of workmanship throughout a single treatment that might last many months or even years, mean that tapestry conservation has to some extent evolved as a separate discipline.
Until the second half of the 20th century, tapestries that showed signs of deterioration were restored rather than conserved. Restoration generally entailed the removal of all weak fibers, such as friable silk weft, and the replacement of damaged areas by reweaving. In this way, the appearance of the tapestry was renewed, and the repaired areas became an integral part of the structure. This approach was acceptable when the materials and weaving skills matched those of the original, or when the work was carried out by the workshop that made the tapestry in the first place. However, much damage has been caused by unskilled restorers using substandard materials, especially in the 19th and 20th centuries. The reweaving often ignores the finer details and coloring of the original, producing results that dramatically change the aesthetic quality of the weaving. Conservation, on the other hand, seeks a compromise that enables the viewer to perceive the original intentions of the designer and weaver without being distracted by the areas that have been damaged. The usual solution is a sewing technique that reduces the visual discrepancy between the damaged and intact areas but cannot be mistaken for the original weaving; nor does it require the removal of any of the original yarn.
The deterioration of tapestries is the result of weaknesses inherent in their structure, added to external factors. While some tapestries are woven with a vertical warp, nearly all historic ones are woven so that the warp lies horizontally as the tapestry hangs. This means that the weight of the hanging is borne by the weft threads, and in tapestry-weaving the weft is not continuous from one side to the other but is joined together in various ways (see also Tapestry). The sheer weight of the tapestry, combined with its movement in relation to environmental changes (see Conservation and restoration, §II, 1), can put a considerable strain on the woven structure, and joins in the weft are potential weak spots. Certain areas are especially vulnerable: slits that were left open by the weaver, to emphasize a line or exaggerate a form, can gape and become distorted, as can those where the sewing thread has broken. The line between two blocks of weft, where one yarn is interlocked around another, is also vulnerable, especially when one area is woven in wool and the other in silk. Any warps that have been exposed by the loss of weft yarns will hang in swags and eventually break, becoming blackened from deposits of dust and dirt.
Tapestries that are hung within an ornate framework often fare better than those that hang free from the top edge. All four sides of the tapestry are attached to a stretcher beneath the frame, meaning that the warp is pulled taut. Thus the weight of the textile is more evenly distributed and is not taken entirely by the weft. However, once areas have weakened, the tapestry can drop or stretch even within a frame, causing bulging across the bottom edge and appearing to be held up too tightly at the sides.
Other damage, often less immediately visible, may be caused by external factors. The photochemical action of light will break down silk fibers, resulting in large areas of weft loss, notably in the sky or in highlighted details of the design. Long exposure to light will cause dyes to fade, and this may only become apparent when the face of the tapestry is compared with the reverse. Dyes applied with an iron mordant, namely shades of brown to black, can cause wool fibers to deteriorate faster, again resulting in loss and definition of the image (see Dye, §2). Insect attack may remain undetected for years, and, especially in tapestries of a fine warp count, surface grazing and tiny moth holes may only be discovered when detailed examination takes place during conservation. If two or more warps have been eaten through, dust will eventually collect around the ends of the wool yarn, causing unsightly dark spots in the weaving.
Tapestries, like any other textile, are best protected in the first instance by good preventive conservation practice. This means control of the display environment, management of light exposure, and pest monitoring. In addition, the appearance and safety of the tapestry will be improved by the attachment of a suitable hanging mechanism. It is important that the weight of the tapestry be distributed evenly along the top edge to avoid specific points of strain.
When conservation treatment becomes necessary, a thorough initial examination takes place. This establishes why, where, and to what extent damage has occurred, how much original weaving remains, and whether the tapestry requires only first aid, as a preventive measure, or full conservation.
First aid may involve surface vacuuming, checking and sewing of slits, relining, and the application of a new hanging mechanism. If no other interventive treatment is required, vacuuming can be carried out while the tapestry is hanging. The vacuum-cleaner nozzle is held close to, but not touching, the surface of the weave, while a soft hand-held brush is used to gently move the dust toward the nozzle.
Full conservation first requires the removal of all extraneous material such as linings, old repairs, or applied patches. Extensive restorations are not necessarily removed, unless they are causing distortion or are visually disturbing. Many old tapestries are very dirty and can be much improved by surface cleaning followed by washing. Wet cleaning, however, is irreversible and can be destructive, so should only be undertaken after dyes have been color-tested and the condition of the tapestry carefully assessed. If large areas of silk weft are friable, they may be lost when the tapestry is immersed in water. Wool yarn, too, may be so damaged that it will break up during the cleaning process. If a tapestry is washed by immersion in a flat bath, then weak areas are normally protected by a temporary covering of fine net with holding stitches to keep bare warps aligned.
The amount of loss can be mitigated by the choice of cleaning methodology. The safest method of wet cleaning is by means of aerosol suction, a process which has evolved since the early 1980s, firstly in Belgium and subsequently elsewhere in Europe. The traditional “bath” method relies on immersion in a depth of water, whereas the aerosol suction method can be likened to a shower. The tapestry is laid face up on a thin layer of supportive foam on a perforated steel platform. The platform is contained in what can be described as a large shower cubicle. The aerosol, a calculated mix of air, water, and non-ionic detergent, fills the cubicle and is drawn slowly through the tapestry by a controlled suction of air through the platform. Samples of dirty water are collected for measuring pH and conductivity. The wash phase is followed by spray rinsing with both soft and de-ionized water. The tapestry is finally blotted with drying paper and toweling, and left flat to dry. The air suction runs continuously through the whole process. The wash and drying cycle takes between eight to ten hours. If the warp yarn is cotton or linen, the drying period may be longer. The procedure can be modified, depending on the size and needs of the tapestry. One of the greatest advantages of this method is the control of fugitive dyes.
A full stitched conservation treatment requires the addition of a lightweight fabric attached to the reverse of the tapestry to support all sewing repairs. If weak areas are few and isolated from each other, small patches of fabric may suffice. Often, however, a full support is required. This should be a strong, undyed, lightweight fabric stripped of all impurities and dressings. Fabric choices differ from country to country and range from cotton, cotton/polyester mix fabrics to linen. Wool is not used, as it would attract pests. When the fabric is measured and prepared, allowances are made for a certain amount of fullness, which is taken up by the stitching. This extra fullness also enables movement in both the tapestry and support after conservation which may result from environmental change, although some methodologies are designed to restrict movement in order to reduce points of strain.
In the UK the normal practice is to sew the tapestry and support together section by section. Work is carried out on a frame with three rollers (see fig.). The support fabric occupies the front and middle rollers. The tapestry, attached to the back roller with the warp lying at right angles to the roller, is taken over the middle roller to rest on the support fabric. As work proceeds, the tapestry and support are sewn together and detailed conservation stitching is carried out, each completed section being rolled on to the front roller. Woven slits are sewn up, broken and missing warps replaced, and bare warps and weak weft secured with warp couching: a spaced darning technique in which lines of stitches are worked over and under alternate warps. Parallel lines are worked c. 2–3 mm apart, each line of stitches being taken over warps that were not covered in the previous row.
Yarns are chosen to blend into the original weaving, both in color and texture, but when no evidence of the original color exists a neutral tone is used. Where whole areas are missing, couching in appropriate colors is worked to suggest the original design. Certain schools of thought believe that this practice is unethical, and that what remains must be accepted as it is without embellishment. This may be reasonable in certain circumstances, but the appearance and understanding of the image may be seriously impaired if there are extensive areas of missing weft. An alternative for infilling large areas of loss is to introduce a dyed fabric or digitally printed patch. The latter has proved extremely successful when an image is taken from a tapestry of the same design. The print also reflects the texture of the weave and print colors can be adapted to suit individual pieces.
Following stitch treatment, the support fabric and warp ends of the tapestry are turned under to neaten. If the galloon (the very outer edge of the tapestry, generally woven in one color) is missing, a replacement may be added. A lining is attached (similar to a curtain lining but again with extra fabric for movement), together with a hanging mechanism such as Velcro®. Methods of hang will depend largely on context of display. When a tapestry is rehung after conservation, the natural drop or stretch of the weave must be taken into account. The tapestry should be left to hang freely for a short period to allow it to find its own level before lining or fixing to a stretcher frame. Even if this precaution is taken, later adjustments may be necessary.
See also Conservation of textiles.
- Lemberg, M. “The Problem of Brown Wool in Mediaeval Tapestries: The Restoration of the Fourth Caesar Tapestry.” In Studies in Textile History in Memory of Harold B. Burnham, ed. V. Gervers, 178–183. Toronto, 1977.
- Hefford, W. “‘Bread, Brushes and Brooms’: Aspects of Tapestry Restoration in England, 1660–1760.” In Acts of the Tapestry Symposium: San Francisco, November 1976, edited by Anna G. Bennett, 67–75. San Francisco: The Museums, 1979.
- Marko, K., Blyth, V., and Kendall, J. “Three Methods of Handling and Washing Large Tapestry Hangings.” The Conservator 5 (1981): 1–8.
- Hartog, F. “An Away Day to Belgium—Washing Tapestries.” Victoria and Albert Museum Conservation Journal 48 (Autumn 2004): 6–7.
- Lennard, F. “Preserving Image and Structure: Tapestry Conservation in Europe and the United States.” Reviews in Conservation 6 (2006).
- Lennard, F. and Hayward, M., eds. Tapestry Conservation: Principles and Practice. Amsterdam, 2006.