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THANGKA RESTORATION AND CONSERVATION

Marion Boyer
Jean Michel Terrier

June 19, 2003

(click on small images for large images with descriptions)


Fig. 1

One of the defining technical characteristics of a thangka 1, its most distinctive feature, is that it is painted on both sides. Thangkas are painted on a canvas support prepared and coated on both sides. Thangkas are rolled, as Chinese and Japanese works often are. The back of a thangka is as carefully prepared as the front, so that consecrated formulas, mantras, and other religious or historical writings can be inscribed on it. Before the 15th century, a pair of presentation frame textiles in cotton or silk was added by a single seam on its upper and its lower borders only, with the sides left unframed. Later thangka mounting included textiles on all four sides of the painting, usually in silk brocade.

All these particularities make restoration and conservation of thangkas a very specific job. Their conception, the place where they were kept and the way they were handled have also to be taken into consideration. Thangkas are exclusively religious works of art, honored in monasteries or private shrines, incessantly rolled and unrolled by the light of the butter lamps - this latter a cause of dirtiness we do not find in the painting of western countries. Many thangkas have been vandalized during the last 50 years as a result of the terrible cultural upheavals in Tibet during the period of the Cultural Revolution. This set of conditions causes specific mechanical wear, and alterations, which will be briefly described in this paper.


Fig. 2

Tibetan paintings have to be freely rolled and unrolled. In their original form, they come with neither easel nor frame, the presentation textiles sewed on their upper and lower borders being there only for display purposes. Considering that both sides of a thangka have to be visible, we had to develop very specific conditions of conservation. New theoretical, methodological and solutions had to be found, combining occidental technology with Tibetan history and practice.


Fig. 3

The restorer will find in a thangka a normal size painting with the graphic precision of a miniature or an illumination. The basic elements of Tibetan painting are accurate drawing and juxtaposition of shaded colored areas. The accuracy, even the miniaturism of the painting of a thangka, the indispensable comprehensive knowledge of the depicted subject, exponentially increases the difficulty of any intervention on a painting.

The Buddhist Tibetan pantheon is very complex. Thangkas are the expression of this pantheon and they reflect its complexity by an extremely varied iconography.

 

METHODS USED IN MUSEUMS AND COLLECTIONS UP TO THE PRESENT

In France, before the 60's, most Tibetan paintings were kept at the Guimet Museum and were restored by a famous Parisian relining workshop with an exclusively occidental approach. Torn thangkas or thangkas with a weakened support were lined and stretched on a frame, which made it impossible to see their back or roll them.


Fig. 4

In the USA, to let the back of the thangka be viewed, some restorers had the idea to glue it on a Plexiglas pane, more or less thick but also somewhat flexible, with a synthetic adhesive. Again, the ability to roll the thangka was lost, and so was the aesthetic of its original display.

Some thangkas were transferred onto a paper support, in the Chinese or Japanese way, but this process crushes, flattens, and stiffens a work of art that draws all its beauty from movement, depth of field, and suppleness. This method also occults the back of the thangka.

Sometimes the presentation textiles were removed, or inappropriately replaced by others with no consideration for style or period.

As to the treatment applied to the pictorial coating, the ignorance of the original Tibetan techniques lead to practices with often disastrous results, practices such as:

- Use of high retention solvents
- Use of vacuum tables wearing out the edges of the tears unprotected by the coating
- Drastic cleansing without taking into account that each coating or color requires a specific treatment
- Use of aggressive and non-selective varnishes that spoil the specific shine of the different original paints


Fig. 5

Since the 1960s -1970s, the thangkas arriving on the market have shown occasional traditional Tibetan restorations made with small sewed or glued pieces of textiles. These restorations were quite rare, and often rough, with a minimum intervention on the surface of the painting. In fact a real traditional Tibetan method exists, involving the sewing or gluing of a strip of canvas into the larger cloth, and then an integration is made with a final coating; but they used this technique only for the initial preparation of the canvas and never for restoration purposes.

To sum up we can say that many attempts have been made to find a suitable method of conservation for these specific works of art, none of them being satisfactory. In Tibet, the concept of restoration and conservation is relatively unknown, and paintings were left in their original condition, or replaced.

EXAMINATION: DEVELOPMENT OF OUR METHOD

First, we perform a thorough examination of the work of art, following the usual scheme.

Treatment of the support

Whenever an intervention or consolidation of the support is necessary, it is crucial that it should be done without lining. Conventional restoration of easel painting with a very degraded support is usually conducted by relining and doubling techniques; as thangkas are painted on both sides, as they need to be rolled and unrolled freely 2, we have to deal with a totally different problem.

Problems on the support of the Thangka

To understand and analyze the alteration of the thangka support - which is often a problem with the glue - it is sufficient to examine the dynamics and the flexibility of the feel of the roll of the painting (as long as the painting is unencumbered with previous restorations or linings).


Fig. 6

Fig. 7

Fig. 8

There are several elements and possibilities in the "roll" of a thangka:

- The roll is rather firm, flexible, without tear, but an examination in transmitted light reveals a variable state of lacuna. When a thangka has not been too much handled, the weaving remains strong, even if a traction at the periphery of a lacuna could in term reduce the resistance of the fiber, leading first to a crack, then to the unweaving of its edges, then eventually to a tear or a hole.
- The roll is very soft, dry and fragile. This could be caused by a sizing problem, loss of molecular linking in the glue, or by a bad initial preparation of the thangka
- The roll is affected by previous rudimentary restorations
- Evidence of vandalism or neglect: tearing, wrenching, laceration, maculation, stamping, crumpling.
- In later thangkas (after the 15th century), a presentation textile (often made of silk) is sewed on the four borders of the paintings, and can react to humidity problems in various ways.

RESTORATION: CONDUCTING OF THE METHOD

We will keep in mind at all times the need for preserving the homogeneity and organic quality of a thangka. We need a comprehensive perception of the work of art and a comprehensive treatment involving its whole, as a coherent and living body, and resulting in a display in total visibility of its two sides, free from all constraint.

1. Preliminary


Fig. 9

Fig. 10

A first visual analysis should show if straightening and cleaning is necessary - it is indicated when we find:

- patches and various restorations on the back of Thangka
- too brittle and very dry paint
- various mutilations by animals (usually rats)
- very greasy stains
- general state of dirtiness

2. The straightening

The restorer will lay a rather flexible intercalated support on his/her working table. This support is compulsory for every intervention. The straightening will proceed with a light moistening and a low temperature ironing using a protective film of sulfured paper (greaseproof paper), done with a steady movement on the back of the thangka.

When the painting has recovered its position and its natural cohesion, we can start the process of preparing inserts for damaged areas, and the thread-to-thread attachment of these inserts. The original dimensions should be rediscovered and the painting rebalanced to preserve the integrity of the whole.

The upper and lower borders are important for the display and the hanging of the painting: they should be given the necessary solidity. The lateral borders, if present, will help prevent horizontal cracks from appearing and will help consolidate the previous work.

3. The preparation of a repair inset and the thread-to-thread operation to join to the original

To proceed to a thread-to-thread operation, particular care should be given to the choice of the textiles to be used: quality of the cloth, the thread torsion, weaving, composition of the fiber, dye, suppleness have to be thoroughly checked.

In the case of a lacuna, the first task is to eliminate the fraying and the greasy residues at the end of the fibers. It is very delicate task, with many possible variants: as the threads may be dry or brittle, numerous or scarce fibers, etc. Once the fibers are clean, they are finely carded on ½ millimeter at the utmost.


Fig. 11

An insert of canvas is prepared; the shape of the lacuna is accurately reported on it, using tracing paper. The edges of the insert cloth are carded the same way as the edge of the original. The canvas is "decatie" on a frame and is then prepared: dyed, glued on both sides with starch or animal glue and glycerin. The coating is then colored with watercolor or pigments.

The assemblage of insert to original is done on the back of the painting, by the millimeters of free fiber ends, using a diluted flexible non-acid vinyl glue in adequate quantity (aqueous emulsion of vinyl homopolymers). The sure cohesion of the two parts is obtained by applying pressure.

The point of the operation is to prevent the zone of the insert from becoming a weakening or weakened area in the future or a source of cracking for the coating plaster and pictorial layer; and to integrate it into the flexibility and the weave of the whole painting.

4. The refixing: The reintegration of the coating or gesso on the back of the painting


Fig. 12

We can then proceed to the refixing of the painting, partial or general, with diluted animal glue. This is the determining operation on the backside of the thangka, which has been untouched till now.

The efficiency of this consolidation of the support will give the intervention its final quality.

The work of art is not, at this state before refixing, totally mechanically safe, as the fibers are still free on the back of the thangka and if not filled up, this would cause, unilateral tractions prejudicial to the work of art.

The colored gesso is prepared with adequate animal glue with kaolin and chalk: kaolin gives flexibility; chalk makes the load. These materials should have a density and strength slightly inferior to that of the original work of art; the coating should be very finely ground and very homogeneous, laid while fluid with a brush. All the ingredients will be prepared and tested by the restorer. Their reversibility must be maximal.

5. The cleaning (method and cases)


Fig. 13

Fig. 14

The analysis of the paint composition allows us to carry out this most delicate operation. If, for example, the percentage of dyes in the paint is very high, the cleansing will require maximal care. If orpiment dominates, a balance will be hard to obtain as its surface tends to oxidate. A too brutal cleaning could be irreversible.

Various cleaning techniques can be used such as:

- A mechanical removal of the dust particles on the colored zone depending on their homogeneity.
- A surface hypotensor in feeble percentage can be used in a selective manner, and without any rubbing ever.

6. The reintegration of the pictorial coating


Fig. 15

The reintegration of the gesso coating is made with the same mix of chalk, kaolin and glue as the one used on the back of the painting, and laid with the same care.

The common factor in these various techniques is the extreme attention and rigor applied to the execution of each stage. A coating laid on an inadequate assemblage would create a breaking point during future handling.

Considering the specificity of the original pictorial techniques, our techniques of reintegration involves making all our colors, including the choice and grinding of pigments as well as the percentage and mixing of the binders.

7. Final evaluation of the restored work of art

We must keep in mind that the ultimate aim is to restitute the original coherence of the work. Therefore we will constantly throw the process back to revise, if necessary, the choices made, to ponder the relative importance to give to each color. It is also important to let the painting rest while work is performed, to position it vertically from time to time in order to consider the progress, and above all to avoid carrying the intervention too far from fear of losing the bloom of the painting.

The Authors are grateful to Maria Frasquet Rosete for her skillful technical assistance.

NOTES

1. thang plain, flatlands; plain, steppe, soup, flat area, prairie, broth, flatlands
thang ka - Tibetan scroll painting, hanging scroll / painting, image, tangka, image [of a yidam]
thang ka - thangka Skt pata. A painting on cloth.
http://www.nitartha.org/dictionary_searchback.html
for search on "thang" [back]

2.With modern occidental advertising posters, a cotton cloth doubling allow the poster to be rolled and unrolled. [back]

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