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Red Maitreya Temple - Leh, Ladakh
Mural Conservation Project (Part 2)
By Anca Nicolaescu and André Alexander
A Tibet Heritage Fund Program Conservation Treatment The conservation project described in the previous number of the magazine had started in 2005 and is still ongoing. The whole project concept was built on the use of natural materials due to their compatibility with the original and availability in the area. Synthetic materials were used either in cases where the natural ones were inefficient or just for trials to be able to observe their results periodically for future investigations. Firstly preventive treatments for addressing the causes of damage or decay of the murals and the architectural systems they embellish were preferred. The THF team of architects, after extensive surveys and building analysis, found that the building is sound but that the parapets were badly disintegrated and the top soil and clay roof layers needed to be re-done. Therefore, the first interventions were done on architecture structure in order to stabilize the conservation state of murals. The small roof above the Maitreya statue was restored; water spouts were replaced and improved and the roof parapets were extensively repaired using slate stone for water proofing. At the floor level the area from the north side of the ambulatory was temporary raised by layers of rubble stones in order to stop the water infiltration, the main cause for the original painting losses in that area. The stone layers do not transmit water and serve as a convenient walking ground to see the remaining paintings while performing circumambulation. For weathering protection the opening from the end of the north wall was closed (Figures 1, 2). The remedial interventions were based on systematic in situ research of materials and their behavior. Trials were done prior to any decision taken and extensive treatments were firstly done only on the most endangered areas where more losses of surface could have occurred otherwise. One of the initial tasks was to establish the real extent of the original paint surface which was covered with two and sometimes three different plaster layers. Moreover the mortar used for the infilling of the gaps was overlapping the edges of the original painting. Based on the results of the stratigraphical trials done and recorded previously (Figure 3), the first interventions at the support layer began with the removal of the improper previous fillings, starting from the edges in order to protect the original surface and to avoid further losses of original support. The mortar layers were removed one by one very carefully by mechanical means, starting with different types of scalpels, chisels or fiberglass sticks. In larger areas where the painted surface was stable a small hammer and chisel were used. After this intervention, mortar traces remained on the paint layer but they were left for further more specific cleaning operations. The most important interventions at the support level were the infilling of the gaps and consolidation of the detachments. Several testes were carried out in order to establish the suitable composition for mortar and grout, compatible with the original one. For fillings, the composition was based only on locally available materials: earth, sand, local clay (markalak1) and organic inclusions – straws, same as used in the painting support (Figure 4). Observing the original existing mortars we set up the characteristics to be followed for the new material:
- porosity;
- mechanical resistance; - adhesive power; - workability; - linear shrinkage. For observation the mortars were applied on mud bricks or/and directly on the walls. The goal of the test phase was to choose the right composition, proportion and size of the ingredients in order to find a good material with similar physical-mechanical, plasticity and linear shrinkage characteristics. Figures 1 and 2. For weathering protection the opening from the end of the north wall was closed;
Figure 3. Example of stratigraphic trial sheet made for identification of the mural painting edges on the west wall.
Figure 5. Filling of the support gaps.
Figure 9. The final layer of mortar, applied under the original level of the painting was washed for obtaining a rough aspect.
Two types of mortar were chosen; one rough for filling in the deep gaps of the support layer and a finer one for the final layer.
The rough mortar composition was: sand 1p + gravel 1p + medium earth 4p + markalak 1p + straw, which mainly offered good mechanical qualities due the well-shaped grain size distribution of the aggregate, minimal shrinkage, good adhesive power, and a suitable hardness relative to the original plaster. From the workability point of view its coarse characteristics permit a thick layer application useful for deeper gaps, avoiding the application of too many layers, which can lead to future damages. Moreover its rough texture enables better attachment for subsequent plaster layers. For the fine mortar the mixture chosen was: fine sieved sand 1p + fine sieved earth 2p + markalak 0,5p, which had very good adhesive power, cohesion and stability and at the same time a similar hardness and porosity to the original intonaco plaster. Beside its function of securing the area of the gaps, this last mortar layer should have an aesthetical impact on the final perception of the murals, thus the color and texture were factors in choosing its composition. The mortar was applied using spatulas or special trowels in successive layers leaving a sufficient time for drying (Figures 5-8). The surface of the final layer of mortar which was part of the final aesthetical presentation was washed very carefully at the end with a special absorbing sponge in order to obtain an even and slightly rough aspect for both the aesthetical appearance and future interventions reasons (adherence of some other layers if necessary in some areas) (Figure 9). For the consolidation of the support detachments different grout mixtures were tested for desired performance characteristics and working properties. The ingredients used in trials were: local materials - clay (markalak), yellow earth; different additional components as pumice, glass microspheres (Scotchilite K1™), Casein, Acril 33, Syton X30 and small quantities of whipped egg white (Figure 10). Different types of grout have been injected for observations in mud bricks and sometimes original plaster fragments were grouted in situ to evaluate their adhesion (Figure 11, 12). Beside the compatibility of the grout with the original support which so far has been done only experimental in situ (further scientific and systematic research is required for an extensive treatment), another important selection criteria was the water quantity required by the respective composition. Having in mind the sensitivity to water of the original mural components, more water than necessary can be harmful for physical, chemical and mechanical reasons: dissolution, expansion/contraction, salt migration and risk of detachment can result. Also, yellow stains appear due to the organic materials from the support2 (Figure 13). Two mixtures had good results so far after observing their behavior during the injection (fluidity and sedimentation) and after drying (retraction, cracking, adhesive power and water drop absorption): - yellow earth, markalak and Syton X30 3%: 10ml which was injected in small endangered area and had very good results from the adherence point of view (Figure 14); - yellow earth, markalak, pumice, Scotchilite and whippet egg white3. For extended treatment it is important to be able to evaluate the results several months after the intervention and to re-orientate the method if necessary.
Figure 10. Materials tested for the grout; Figure 11. The observation of different types of grout injected in mud bricks; Figure 12. Tests for grout injection in mud bricks; Figure 13. Organic components of the support can produce yellow stains on the original, this was avoided by using Japanese paper facing; Figure 14. Consolidation of support small detachments.
Interventions at the paint layer level
The main treatment problem at this level was posed by the overcoating layers which were covering the original. As mentioned in the conservation assessments, the paint layer being water sensitive and already damaged (flaking and powdering were occurring before the overcoat was applied), it suffered even more deteriorations during the over plastering due to both the very liquid application and perfect compatibility between the original and the overcoat layers. Thus the paint layer and the new plasters interacted forming a common mass which in some areas was almost impossible to separate. Particularly, the first overcoat layer (markalak) produced in time (or even from the beginning, during its drying process) grave damages due to a very good adherence, strapping the original which was more adherent to the overcoat than to the original support. Therefore, the treatments were combined, most of the time the removal of the overcoat layers being alternated with the fixation of the paint layer. Several materials and methods were tried in order to elaborate the best approach. Removal of the overcoat layers Following stratigraphical trials we determined that two main layers were covering the original: the first one in direct contact with the paint layer was a very uneven layer of markalak while the second was a thin white wash. The upper parts of the walls were covered only with the white wash. Removal of the white wash The white wash layer was very powdery and not adherent to the surface thus easy to be removed by soft brushes or very absorbent sponges wetted with a very small amount of water (Figure 15). However, the operation needs attention due to the detachments existing in the markalak layer. Also in the upper parts where this layer was applied directly on the powdering paint surface the removal was done carefully with dry cotton swabs. Removal of the markalak layer The removal of the markalak layer was the most difficult and time consuming task due to the wide range of damages on the original paint layer and the tight connection between the paint and the overcoat layers. Tests were carried out prior to the intervention for setting up the right methodology specific for each color, area or existing damage. Considering the paint layer's sensitivity to water, we used mainly dry mechanical methods (cotton swabs, different types of brushes, scalpels, fiber glass pencils, wishab sponges) (Figures 16-22).
Figures 17-22, from left to right. Different cleaning methods used simultaneously or according to the state of the paint layer: hard brush for the markalak layer; Dry cotton swabs or moistened with isopropyl; Cotton swabs used in parallel with soft brush; Cotton swabs with scalpel; Eraser; Aspect of the area after cleaning.
Where the markalak was very thick or uneven applied, the area was first thinned until an even thin layer was obtained so that the paint layer underneath could be easier controlled and checked.
We tried to improve the results of the dry mechanical method using in parallel chemical cleaning. Several solvent mixtures were tried but the best results were obtained with isopropyl alcohol used in powder cellulose poultry (Arbocel BC 200) applied on the markalak layer. The markalak became more powdery this way and easier to remove without affecting the sensitive paint layer. This solution however was not possible to use on areas with detachments or flaking colors.
Figure
24, 25, 26. Different aspects during the cleaning of the overcoating
layers. Figures 27 and 28. Different aspects during the cleaning of the
overplasters.
Depending on the colors, their conservation condition and behavior during the tests, different techniques and tools were used in parallel (Figures 23-28).
For a better view of the treatment results in connection with color, damages and methods, our observations for each color behavior and cleaning technique were gathered (see Table 1). We found this useful for both correlating the damages and the appropriate approaches as well as for future research regarding this issue. During this process the paint layer was fixated simultaneously or/and consecutively using different methodologies further described. After the entire area was already consolidated a last cleaning was done by the mean of wishab sponges in order to remove the white veil which remained from the markalak dust.
Fixation of the paint layer
The fixation of the paint layer was imperative due to the high degradation level which would definitively have led to large losses. On the other hand, this operation implied the use of a fixative material which, if its choice is not based on sufficient research regarding the original materials, damages and effects, could produce undesirable consequences in the future, leading even to grave changes of the initial proprieties and conservation condition of the original. Therefore we chose animal glue as fixative, which is very compatible with the original (knowing that the original binding agent was animal glue), avoiding thereby unexpected future reactions. After checking the local animal glue used as binder even nowadays we decided that its level of chemic impurity (color and unknown particles) could affect the original. Therefore it was decided to use the fish glue injected or sprayed depending on the damages type (powdering or flaking paint layer). Some other fixatives were used but only in areas where the animal glue was not effective or in trials for future observations and research, being aware that future investigations and periodic evaluations of the results are needed in order to re-orient the method if necessary. Thus, the different materials and methods used according with the damages necessities were:
Table 1. Observations during the cleaning of the west wall (first year’s intervention). Other recordings were added later.
Figures 31 and 32. Before and after the fixation treatment of the paint layer. Figures 33 - 35. Paint layer consolidation.
Fish glue (2-4%) For the powdering areas the warm glue was sprayed (Figure 29) on the surface. Depending on the absorption level of the paint layer some alcohol was sprayed before for a better penetration. After the fixative was totally absorbed by the paint layer the surface was gently pressed with a special rubber roller over a layer of Japanese paper and a layer of polyester foil (melinex) applied as protection (Figure 30). Observing the behavious of the surface after the treatment, sometimes the operation was repeated. Very good results were obtained with this method - the adherence was reestablished and the original paint aspect preserved (Figures 31, 32). For a better control of the penetration of the glue into the big flaking areas it was seen that injected fish glue gives very good results. This approach was used for some areas, the methodology afterwards being the same as described above. For consolidating the paint layer strapped by the markalak the warm fish glue was injected in the damaged area (Figure 33) then the surface was laid down on the support by means of a spatula or special rubber roller (Figure 34). The adherence of the paint to the support was resolved in this way but the markalak layer became harder to remove as the glue was absorbed by the markalak layer and thus the paint layer could have suffered damages during the cleaning (Figure 35). Therefore more trials with different materials were required for obtaining better results. Paraloid B72 (5% in acetone) Trials were also done with Paraloid B72 for consolidating the paint layer strapped by the markalak. Japanese paper facing with CMC was applied on the markalak and the detachment was opened. Paraloid 5% in acetone was applied on both the back of the strapped paint film remained on the markalak and on the support area from where the paint layer was strapped (Figure 36). When the Paraloid was dry, acetone was brushed on the support surface in order to reactivate it and the strapped fragment was pressed back on the support using a special rubber rolle (Figure 37). After the perfect drying of the surface, the facing was removed by wet cotton swabs and the markalak was removed mechanically or with a mixture of water – isopropyl (Figures 38, 39). This method had good results but only where the paint layer was compactly strapped by the markalak and not very connected to it. The fixed paint layer suffered no changes in its original matte aspect. For areas where only small fragments of the original color were strapped the method did not work due to both the difficulty of applying Paraloid on small support lacunae (from where the color was strapped) and the fast evaporation rate of the acetone (not enough time to be applied on all of the fragments without getting dry or over touching the surrounding areas). Further research will be useful for finding an efficient solution for this specific paint layer deterioration. Rabbit glue (4%) In the areas where the paint layer was detached together with parts from the preparatory layer, the rabbit glue was more appropriate to use due to both its better adhesive power and its capacity of creating a thin layer which could provide a better ground for pasting of thick layers. The warm glue was injected in the detachment area and pressed with a spatula or a special rubber roller over a melinex foil. In the areas where part of the support was lost and the paint layer had nothing to lay on we used as filler (before fixing the paint) sieved earth in mixture with rabbit glue which was applied by spatulas. Very good results were obtained with this method, the paint layer becoming stable.
Cleaning
Beside the removal of the over-plasters and the mechanical cleaning with the wishab sponge as described above, several cleaning trials were done in the lower part of the west wall (on the donors frieze) were dust and soot had altered the original aspect of the murals due to the use of the butter lamps. Trials were carried out with different solvent mixtures: - acetone – alcohol (1:1) – the dust and remains from the over-plaster removal were satisfactorily cleaned; - acetone - isopropyl (1:1) – better results; - isopropyl in cellulose paste poultry (Arbocel) - good results; - isopropyl in Japanese and napkins poultry pressed with a rubber roller – very good results. Very good results were also obtained by mechanical means, using fiberglass sticks of different thicknesses. Considerations regarding the final aesthetical presentation of the paintings The temple, still regularly used for ritual purposes, it is not preserved as historic monument but as a living and active – even interactive – space between art, spirituality and those people who step inside it. From this reason an intervention strategy was established for choosing an appropriate final presentation, able to eliminate the divergences between the correct chromatic retouching without creating a fake and the recovery of the integrity of the art work demanded by its religious function. First of all, the lacunae were classified from two points of view: stratigraphically, categorizing them due to the level where they appeared: erosions of the paint layer (irregularities of the paint hue due to some slightly mechanical damages or chemical alteration), lacunae in the paint layer (losses of the paint layer), superficial support lacunae (losses of the support at the intonaco level) and deep lacunae of the support layer (losses of the support at the arriccio level). From the image perception point of view lacunae were divided in several types: lacunae that can be integrated (erosions of the paint layer), lacunae which can be integrated by a reconstructive process (they must be of small dimensions and located in areas which preserve enough original elements) and large lacuna fields which cannot be retouched. This simple organization of the damages was helpful for setting up a retouching methodology where same types of lacunae were to be treated in similar way on the whole ensemble for obtaining a final unity. Another aspect of the retouching stage was choosing the right media to be used for preserving the original matte aspect and being reversible as much as possible.
Figure 43. Retouching tests with pastels (left side) and pigments with binder (right side);
Figures 45 and 46. Chromatic reintegration by velatura. Figure 49. Chromatic reintegration of the paint layer.
Even though the area retouched using pastel was reaching a good chromatic aspect, this methodology was impossible to use on all types of lacunae. The trials done with Klucel G as binder and mineral pigments gave very good results: easy to be applied even on very small erosions and in same time very reversible with alcohol which is not affecting the water sensitive original murals. Having chosen the materials to be used, the retouching techniques were selected depending on the nature of the lacunae. The very small and superficial ones were integrated with a light glaze which permits the recovering of the surface evenness without the alteration of the rest of the paint layer (Figure 45-48). Retouching the lacunae of the paint layer that were disturbing the image not only due to surface alteration but also due to the small white or light colors of the appearing support was done by means of transparent glazes (velatura) applied in dots using neutrals colors. As a result, the white spots of the paint gaps were optically pushed backwards leaving the original readable. The reconstructive method used for the superficial support gaps was the hatching technique (tratteggio) using watercolors this time because the retouching was done on new support, able to be removed if necessary.
Figure 50. Chromatic reintegration by tratteggio; Figure 51. Before chromatic reintegration of the paint layer; Figure 52, 53. Chromatic reintegration of the paint layer.
Before THF’s project, there has been not a single Ladakhi restorer. Conservation projects in the region always involved only foreign or Indian mainland experts. Therefore, the involvement and training of locals was an important aspect of the project. The two most promising students have completed an internship in Germany at the conservation laboratories of Erfurt University of Applied Science in May - July 2007. These two and other trainees will participate in the project to gain further training. They have already gained good knowledge and skills regarding conservation issues and respect of heritage authenticity and thus, hopefully, they will be able to maintain their valuable heritage in the future. Conclusion What we had presented in this paper are all our experimental interventions and trials which must be re-evaluated regularly and followed by more systematic researches. That is the reason why the needed extensive treatments were done only with glue instead of the local animal glue, avoiding hence uncontrollable future damages. At the end of this project, murals from the first half of 15th century were recovered in Red Maitreya, being now the oldest extant paintings in Leh. Several key historic sites in Ladakh preserve comparable historic art, but almost all of them require urgent conservation intervention. Many have been lost in the past 2 decades. The investigation of the paintings in the Red Maitreya Temple of Leh has allowed first conclusions as to the technologies and conservational challenges of early Western Himalayan hoping that questions have been raised for future investigations. Acknowledgments: We wish to thank to the project sponsors Trace Foundation New York and InWent Germany; Erfurt University of Applied Sciences – Germany for their cooperation which made the project possible thorough students volunteering (Hanna Pohle, Derya Pektas, Jana Bulir, Olga Emgrund, Sonia Cabela, Anke Farnik, Rebekka Ewert and Jovanna Glaß) and their professor Meinhart Landmann; and to the devoted local trainees Jangchen Dolma and Skarma Lotus. The National Research Laboratory for Conservation and Restoration of National Cultural Heritage (LNC) – Romania especially to Prof. Gheorghe Niculescu Director of LNC and his team (Dr. Olimpia Hinamasuri Barbu and Dr. Georgescu Migdonia) for all the scientific research presented here. Notes:
1. Markalak is local clay consisting of 62% clay, 30% calcium carbonate and 8% silt.
2. The appearance of the yellow stains was avoided by a thick Japanese paper facing glued with Klucel G (hydroxypropyl cellulose) in ethanol. Thus the stain was remaining on the paper – the evaporation was done at this paper level. 3. From the available Getty Institute’s literature regarding organic materials in murals – example of grout mixtures used in Dunghuan caves for support consolidation.
References:
1. Stephanie Bogin, A technical Study of the early Buddhist wall paintings at Nako, India, Unpublished Master’s thesis, Courtauld Institute of Art (2004) 2. David Jackson and Janice Jackson, Tibetan Thangka Painting: methods and materials, Snow Lion Publications, New York (1988) 3. Ann Shaftel, "Note on the technique of Tibetan Thangkas", Journal of the American Institute for Conservation, 25 (1), (1986) pp. 97-103 4. Leslie Rainer and Angelyn B. Rivera (ed.), The conservation of decorated surfaces on Earthen Architecture, Getty Publications (2006) 5. Gernot Minke, Building with earth – design and technology of a sustainable architecture, Germany, Birkhauser Basel (2006)
About the authors
Anca Nicolaescu
Contact: ancanicolaescu@yahoo.com Anca Nicolaescu is a Romanian mural painting conservator with Master degree from the University of Fine Arts Bucharest, Conservation-Restoration of art works department. She received recognition as specialist from the Romanian Ministry of Culture in 2005 after having coordinated various distinguished conservation projects. One of the projects (a 17th century mural painting ensemble) done by Restauro Art Grup (the conservation enterprise where she is a co-founder) was awarded in 2004 the "Vasile Dragut" prize for Cultural National Heritage by the Romanian Ministry of Culture. Her work experience includes international participation at conservation projects and seminars in UK, Turkey, Uzbekistan, Japan and India.
André Alexander
Contact: info@tibetheritagefund.org André Alexander was born in West-Berlin in the Year of the Wood Dragon. He currently divides his time between Ladakh, China and Germany. He was trained by traditional master craftsmen in Lhasa in traditional Tibetan architecture, and is currently affiliated with Berlin University of Technology (MSc in Urban Management and PhD candidate in Architecture), where he occasionally lectures. He is co-founder and first chairman of Tibet Heritage Fund, an international non-profit organisation working to preserve the heritage of the Himalayan regions. He has a prodigious publishing activity, from which several articles and reports can be seen online on THF's website. THF - TIBET HERITAGE FUND www.tibetheritagefung.org
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