Volume 8, Number 3, Sept. 1986, pp.2-7

Teotihuacan Mural Project

by Lesley Bone

The Teotihuacan Mural Project began following the death of Harold Wagner in 1976. Wagner was a rather eccentric San Francisco architect who bequeathed his collection of 70 mural fragments to the Fine Arts Museums of San Francisco. His Will took the museums totally by surprise. Although they knew of the collection's existence they never suspected that they were to become its final keepers. The fragments ranged in size from a few inches to 14 feet and originally came from a city in the central valley of Mexico known as Teotihuacan. They date from between 400-700 AD which is known as the Classic Period. This city occupied an area of 9 square miles with an estimated population of 150,000 inhabitants. It must therefore have been one of the largest cities in the world in its time.

Provenance

Mr. Wagner, who had previously been a resident of Mexico, left no documentation which dated the removal of the murals, or described the area of the city from which they had been taken. He did, however, leave sales receipts and notarized statements in his papers. Subsequently Rene Millon, an archaeologist from the University of Rochester, has discovered the specific location from which the murals were removed. It is an area containing two or three palaces located in "the square of the ransacked murals." The palaces lie less than 1/4 mile east of the main pyramid, known as the Pyramid of the Moon. It is thought that these quarters housed some of the government functionaries, or perhaps that they were inhabited by descendants of an old reigning dynasty which had still managed to preserve a high position in Teotihuacan society.

Description of the Fragments

The fragments are about three to five inches thick. They consist of a volcanic ash aggregate which includes clay and pottery shards. This ground is covered with a very thin coating of lime (2 mm) which, in contrast to the coarse backing material, is extremely smooth. The lime layer was painted in fresco, very similar to that technique employed by the Italians. Some of the murals appear to have been burnished, possibly with a smooth stone. Most of the murals are painted in red monotones (a local specular hematite) which make the surface of the mural sparkle. Other colors include white (calcite), green (malachite), yellow (limonite), black (charcoal) and blue (our results on the composition of the blue pigment are at present inconclusive but we are carrying out further tests the results of which will be published at a later date).

The subject matter of the murals range from elaborate priest deities in warrior-like costumes to warrior birds and a wonderful feathered serpent flanked by flowering trees (these contain symbols at their centers which as yet are undeciphered. It is thought that the fragments might belong to five or six murals but the manner in which they interconnect is hard to determine. By careful examination of the edges and surface topography, some idea of their original architectural position can be deduced.

Legal Aspects

This collection of murals was the largest anywhere outside Mexico, and The Fine Arts Museums soon realized the great importance of the bequest and the impact it would make. The collection had been seen in the San Francisco area by several people including a local curator sometime in the late 1960s, so it was deduced that the murals had been removed from Mexico prior to this date. This discovery was significant because it meant that The Fine Art Museums could legally keep the murals in accordance with the 1971 bilateral treaty between Mexico and the United States. This treaty established provisions whereby cultural properties would be returned to the country of origin; however the terms of the treaty were not retroactive.

By coincidence, the Mexican/American treaty was closely followed in 1971 by passage of the UNESCO act for the prevention of imports, exports and transfer of cultural property. Possibly then, in consideration of the UNESCO act, of the size and scope of the collection and of the ethical issues regarding cultural patrimony which were raised by the Wagner collection, the museums approached officials in Mexico to discuss the bequest. It was hoped that a joint program for the conservation and care of the murals, which would include the voluntary return of at least 50% of the collection to Mexico upon the completion of treatment, could be devised.

In 1981 an historical and unprecedented agreement was finally reach between The Fine Arts Museums (FAMSF) and the Instituto Nacional de Anthropologia e Historia de Mexico (INAH). It does provide for the joint conservation, exhibition and disposition of the murals.

Condition of the Murals

While Harold Wagner's Will was in probate, the murals were moved from the Wagner residence to the storage area of the M.H. de Young Museum. During the transfer the murals were mishandled, resulting in some breakage. The settlement of this unfortunate mishap led to the hiring of an outside conservator acting for the moving company, who was to estimate the extent of the damage caused by the move. This was quite a tall order for someone who had never seen the murals before and who could not confer with "in house" conservators or do any tests on the mural fragments. Somehow he managed! This all took quite a protracted period of time. It was eventually settled, but did delay the start of the project.

The condition of the murals, save for the damage caused in transit, was fair. The murals still retained much of their original color. There had been some root damage to the surface which left squiggly marks where pigment had been pulled away. Seepage of water onto the surface had also caused the deposit of clay minerals in some areas, especially on the murals which had originally butted up against the floor. There was some detachment between the lime layer and the volcanic backing but it was not very extensive. There appeared to be no damage from efflorescence that plagues so many European murals.

Harold Wagner left no record of the conservation treatments that he and a group of friends, whom we assume worked under his direction, used on the murals. The mounting techniques were rather cumbersome but for someone with no conservation training Wagner had the good sense to preserve the murals intact as well as to employ materials currently in conservation use at that time. He could so easily have removed the volcanic backing but perhaps his love of architecture prevented him from doing more than was absolutely necessary. Wagner mounted the fragments in a frame which was infilled with cork that butted up against the edges of the mural and was about 1/2" lower than the mural surface. On the back he would place either (1) a thick layer of plaster of Paris, (2) chicken wire inlaid with plaster or (3) wooden battens across cracks and held in place with blobs of plaster. The plaster was faced with a piece of plywood onto which were attached hanging devices. The framed "sandwich" then hung on the wall. Missing areas were filled with plaster of Paris - including shallow areas of root damage - and these were painted to imitate a particular mural section which was lost. These areas of reconstruction generally measured above one inch square. Cracks were sometimes given additional strength by the addition of tow to the plaster. PVA emulsion appears to have been used to consolidate loose and friable areas both on the front and back. The techniques of application were not very precise and at times rather heavy handed, and therefore not very pleasing aesthetically. Only one mural appeared to have had the whole surface consolidated. It showed definite signs of yellowing, making all the original pigments look warmer than had been the original intention.

On the whole, however, great credit must be given to Wagner for having maintained such a restrained approach, and thereby preserving a great deal of ethnological information which, under a more rigorous treatment, might have been lost.

Conservation

Before conservation could begin at the museum, the curators in charge of the project had to determine the nature of the activities to which the murals would be exposed. This was a complex task which placed numerous and sometimes contradictory restrictions on the treatment procedures. The final conservation solution had to allow for exhibition, storage and transport; it also had to permit maximum access to the front, back and sides of the fragments for any subsequent scientific or historical examination. Preservation of the murals' integrity was a primary concern, as was the desire to promote maximum aesthetic impact when on display.

As the project was a collaboration with conservators from INAH, at the Churubusco Center in Mexico, who had had previous experience with this kind of material, it was felt that these conservators might have a viable solution. As it turned out, the method they employed was used extensively on murals that had been removed in the field. They arrive at the laboratory already faced, with the volcanic backing removed. The consulting UNESCO conservator felt that a similar treatment would be too radical for murals that were already off their original walls and in a museum collection with the volcanic backing still intact. If such a method were to be adopted it would also mean that prior curatorial stipulations regarding the parameters of treatment would have to be contravened.

Other conservators who had worked on murals both in the United States and Europe were consulted and it was hoped that by culling all this knowledge together one might come up with the optimum solution. Initially a support system which locked around the mural was developed but this meant that the whole system had to be unscrewed to gain access to the back and sides. It was at this point that Jackie Heuman, who had been the first FAMSF conservator on this project, accepted another position and left the project. Stephen Mellor replaced her. It was Stephen who pioneered the final method that was used to mount those murals which were to stay in San Francisco.

Another interesting aspect of this project was the decision to put the conservation process on public display. With support from Citicorp, the Mellon Foundation, the Kellogg Foundation, the NEA and the Mortimer Fleishacker Foundation, two galleries were transformed into an interpretive center and a conservation laboratory. The interpretive center included information boards, photographs, fragments of murals and, more importantly, a videotape which put the murals into context and explained the proposed conservation treatment. The center had a window into the conservation laboratory. As the project progressed an increasing number of people were required to work in the lab space. At one stage Stephen and I wondered whether the project should have an entry in the Guinness Book of Records; as we tried to maneuver heavy 4' sq. mural fragments in a 19' X 32' space with the help of three technicians, an intern, and in the midst of three Mexican conservators, two Japanese draughtspeople, a photographer, a curator or two and at one unbelievable point a three month old baby appeared on the scene. Throughout, a sense of humor was a requirement. This 'side show' lasted a year and a half after which it was moved down into the conservation laboratory.

When the Mexican team arrived for their first stay in San Francisco they demonstrated their method of treating murals as a starting point from which a joint solution could be developed. This treatment involved facing the front of the mural with two layers of gauze and then applying a flat layer of plaster of Paris onto the gauze so that when the mural was turned over there would be a stable base. A piece of board was fastened onto the plaster and then the mural was turned face down. The old plaster was removed as well as any old supports. The murals' volcanic backing was then removed, either just in the center, so that a two inch edge of original backing was left, or, with the more crumbly ones, all the volcanic backing was removed. The back of the lime layer was supported with a layer of gauze generously impregnated with Calcium caseinate paste (as used by the Moras). Expanded epoxy resin was then used to build up the back into which was embedded the hanging hardware. The epoxy was painted over with a mixture composed of one half Rhoplex AC-33 and one half powdered volcanic backing to simulate the original.

The murals were undoubtedly lighter following treatment. Whereas previously four or five people were required to move a fragment, two could now do it with no effort at all. The amount of pigment that was removed when the facings were lifted was sufficient to produce a mirror image on the gauze and this was deemed unacceptable. The Mexican conservators' understanding and control of the epoxy foam was enviable as we had some trouble, in our experiments, keeping it off the face of the mural. On the whole, in terms of current conservation ideals in the United States, it was felt that this method was too radical and did not fulfill the requirements set down by the De Young curators. For example there was no backing left for historical and scientific study and a great deal of topographical information was lost.

After some discussion it was agreed to leave the volcanic backing intact and not to face the mural before treatment. At this juncture several other solutions were discussed and tried. One included the use of a honeycombed aluminum support embedded into the epoxy foam. Stephen tried using T-section aluminum extrusion to form a structural support which was riveted together where it crossed at four inch square intervals. Clips were then placed all the way around and the structure was embedded with epoxy foam. The Mexican conservators used a similar solution on the murals that were to return to Mexico except that they used a much less substantial aluminum support consisting of two horizontal and two vertical extrusions which were riveted together where they crossed. Their layer of epoxy was much thicker and almost embedded the whole mural. Clips were then randomly placed around the mural fragment. These clips were then riveted to the aluminum support. Another type of support that Stephen tried was an I section aluminum extrusion which was riveted together in the form of a rectangle with bracing bars across opposite corners. The four corners were then cushioned onto the mural back with small rectangles of epoxy foam which were separated from the mural with a parafilm sheet.

Somehow none of these methods seemed to give the murals adequate support and our lack of experience with the use of epoxy foam prevented us from getting the kind of finished result that was acceptable. Stephen also wanted a uniform look for all of the murals. It must be pointed out that the smaller mural fragments tended to look very cumbersome with the thickness of epoxy backing added to the mural's own backing. The clips were of different sizes and in different positions around the edges. This gave an untidy appearance and there was some serious concern as to whether the clips and rivets were giving the murals sufficient support.

It was obvious that the Mexican conservators felt they had already altered their techniques sufficiently to fulfill the curatorial requirements. At the same time Stephen was not going to compromise his conservation ideals and the safety of the murals by accepting a method which he felt could be improved. At this point the Mexican conservators returned home; six months later they came back to San Francisco to complete the work with the method described above. (It was generally felt that once the Mexican portion of the murals were returned to Mexico they would be reconserved using the method which they initially demonstrated).

In San Francisco the conservators consulted a structural engineer and Stephen came up with a neat and simple design which totally avoided the use of foaming epoxy resin. It involved the use of a welded aluminum frame with an epoxy putty lining which cushioned the mural onto the frame. with the minimal use of clips along the bottom (usually four), to give some support, one avoided too much visual disturbance. The fragment was then hung at 15 degrees to the wall by an ingenious use of two metal feet that screwed into the bottom section of the frame. Thus the murals were in effect cradled into place. This mounting technique is very sturdy and works well in storage. It does, however, leave the edges rather exposed during handling, but this problem may be resolved somewhat by using custom-made ethafoam lids which make a barrier to prevent bumping the edges of the murals. The pieces themselves were handled by holding the attached framework. It would probably have been a good idea to have modified the clips so that they could be removed and replaced as needed while retaining their strength. At present they are welded on and therefore have to be sawn off to release the mural from the frame. The murals are still heavy, as the frame and lining add at least 30 pounds to the total weight. But the integrity of the murals was preserved and both the back, sides and front can be examined without removing any of the mount. The murals will not travel as was first intended and therefore the idea of making special custom boxes has not been developed past the prototype stage.

The project was not as straightforward as one might have anticipated but certainly we all learned a great deal about diplomacy, and it is hoped that the murals did not suffer in the process.

The 55 fragments that were returned to Mexico arrived at the beginning of 1986, and were exhibited in February. It is hoped that The Fine Arts Museums of San Francisco will hold an exhibit in the Spring of 1987 of the portion of the collection which remained in San Francisco. A special thank you must be given to Elisabeth Cornu who was the common denominator throughout the project as the project's conservators changed.

Lesley Bone
Associate Conservator
Africa, Oceania & America
The Fine Arts Museums of San Francisco