The Aztec Feather Shield in Vienna: Problems of Conservation
The 450 year old feather shield “Ahuizotl” , formerly kept as part of the Collections of Ambras Castle, is not only one of the most significant, but also one of the most delicate objects of the Museum of Ethnology in Vienna. In terms of conservation related issues, it is one of the most challenging objects. The shield is made from different types of feathers (blue cotinga, scarlet macaw, yellow oriole and rose roseate spoonbill) which are arranged in rows. It is also made from several sheets of gold. The feathers have become very thin, whereas the gold sheets are very fragile by their very nature. Their supporting element is made from the inner bark of an agave tree which has been braided. It is stretched onto a ring of rattan and reinforced with wooden sticks. On the back of the object there is a sheet and two handles made from raw hide. Due to these highly sensitive aspects of the object, every transportation of the object remains a serious challenge for the conservators of the museum. Those damages to the feathers which are caused by oxidation, chemical degradation, light, mechanical deformation and insect attack are usually very obvious. But certain stages of these damages can only be detected on a very microscopic level, e.g. at the little hooks of the feathers which are responsible for holding the vane together.Therefore, even the smallest move or vibration will cause irreversible damage or loss. The main focus for the conservator will therefore be the prevention of any harmful effects on the object.Since its new installation into the gallery “Classical Antiquity of the New World” in 1992, the ceremonial feather shield “Ahuizotl” has been presented in a display case made by the company “Swarovski”. The display case is dust-proof and secured with an alarm. It is equipped with an anti-glare lighting system which operates via fibre glass technique and indirect lighting. The light source (halogen illuminant with variable illumination) is situated in the base of the display case. A fibre optical system channels the light into the display case without the radiation of heat or UV. The illuminance is 50 lux. By inserting Art Sorb Pearls as a buffer for the humidity, the relative humidity in the display case remains as balanced as possible and stays within justifiable limits. Any transportation of feather objects requires highest caution. For the loan of the “Ahuizotl” feather shield to the Royal Academy of Arts in London on occasion of the exhibition “The Aztecs” (November 16th-April 11th 2003), a special travelling box was designed in cooperation with the company “hs art service austria ” In this travelling box, the object rests on a base of two very light panels. These panels are made from polyurethane-foam which is pressed in-between two sheets of acid-free paper (KAPA-panels). The object is fixed to a silicone covered screen which is mounted in-between the panels.To mount the object onto the screen, the panel-screen unit can be vertically stuck into the travelling box. With the help of different space bars, the panel unit is fixed into the travelling box. As a result, no packing material will touch the object. Additionally, the light-weight travelling box will be surrounded by a shook-proof, heavy-weight climate box.
1The permanent collection of the Museum für Völkerkunde in Vienna, which is presently closed for renovation, usually features among its treasures three extremely valuable pieces of Mexican featherwork. They are part of the so-called "Ambras Collection" founded in the second half of the sixteenth century by Archduke Ferdinand of Tyrol. The most famous of these is the only surviving feather headdress from pre-Hispanic Mexico (catalog number 10,402), generally (but erroneously) designated as “Moctezuma's headdress”. Secondly, a feather fan, long considered to be Aztec, but now recognized as colonial (catalog number 43,381). And finally, an early sixteenth-century Aztec ceremonial feather mosaic shield (catalog number 43,380), which will be the main subject of my presentation.
2In the course of the last renovation of the American halls on the second floor of the museum in 1992 the cases and technical installations were brought up to present-day standards and conservation requirements. Together with the other artifacts on display in this section, the three pieces of featherwork have since been displayed in modern glass cases with glass fiber lighting and the possibility for climate control by means of ART-Sorb. The relative humidity within the cases is maintained at 50 percent. In the case of the featherwork, the impact of light is reduced to zero in the ultraviolet range, kept at a very low level in the infrared range, and in the visible radiation is limited to 50 lux. The illumination of the case of the feather headdress is activated at the approach of viewers by a motion detection device.
3This very expensive mode of presentation is necessary because of the extreme fragility and the extraordinary value of the feather artifacts. The same reasons stand behind the arguments against their transportation, which is kept at the necessary minimum by the conservation staff at the Museum für Völkerkunde. Each change in the conditions of their display causes stress on the objects, even short-term withdrawals from their cases for investigations and for photography are representing a danger for the integrity of each single part. For loans and the long-distance transportation required in this connection, the same is true on a much larger scale.
4My presentation is concerned with the loan in 2002 of the ceremonial feather shield (catalog number 43,380) to the Aztec exhibition at the Royal Academy of Arts in London and the problems associated with it. This shield, first mentioned in 1522 as a gift to the Bishop of Palencia, came to Austria in the 1550s as a gift of the current Bishop of Palencia, Don Pedro de la Gasca, to Emperor Ferdinand I and subsequently passed on to the collection of Archduke Ferdinand of Tyrol at Ambras castle near Innsbruck. Large parts of the Ambras collection were – after a series of relocations – taken to Vienna in the course of the Napoleonic Wars during the early nineteenth century. Here they were moved between various repositories, packed and unpacked, carried around from one temporary location to the next, happily escaping destruction by a major fire, and ultimately ending up in 1880 at the recently established Anthropological-Ethnographic Department of the Imperial Museum of Natural History. After the Museum für Völkerkunde emerged from the Anthropological-Ethnographic department in 1928 and moved across the street to its present location in the former Imperial Castle, the feather items were transferred to this building in the 1930s. During the Second World War, the feather pieces were kept in a safe at the National Bank in Vienna. After the war, all of them were at least once displayed at another location in Vienna, and in addition to the trip of the feather shield to London, the feather fan was once taken to an exhibition in Linz, the capital of Upper Austria.
5The nearly five hundred years-old ceremonial feather shield from the Ambras collection is not only one of the most important, but also one of the most sensitive artifacts of the museum, deserving the special attention of the conservators. Of the four surviving Aztec feather mosaic shields, it is the only one featuring a representational design. The construction of the shield consists of two layers of round, twined mats of reed and vegetal-fiber yarn, seventy centimeters in diameter. The reeds of the front mat are arranged vertically, those of the back mat horizontally. The mats are edged with a strip of hide, which is folded around the edges about two centimeters on each side and sewn to the mats.
6At its back, the shield is reinforced with four vertical wooden sticks. In the center there is a rectangular piece of hide of about thirty-six centimeters square. Through this piece and attached to the two inside sticks there are two horizontal carrying straps of leather. Interestingly, these straps are attached in such a manner that in order to show the image on the front side right side up, the arm has to be held vertically. Near the upper edge of the rectangular piece of hide a leather band, which probably served as a suspension, is attached to the two outside wooden sticks. Finally, there are two additional strips of leather stretched out from edge to edge of the shield, each at about one third of the height of the disk. Red pigment is found on one side of the leather bands and straps as well as on the backside rawhide edging and for about 1.5 centimeters along the edging on the reed mats as well.
7The decoration on the front side consists of a feather mosaic showing a blue coyote on a red background with sheet gold decoration, a feather fringe encircling the shield, and feather tassels in the lower half.
8The outline of the coyote and other details are edged with sheet gold, thereby adding to the three-dimensional appearance of the image. The sheet gold pieces have small "wings" by which they are sewn to the base. The feathers used have been identified as blue cotinga, scarlet ara, green quetzal, yellow oriole, and roseate spoonbill. They were glued to amate paper, cut to shape and subsequently glued to the base in a shingled manner. From the mouth of the coyote emerges the Aztec glyph for "water and burnt fields," a metaphor for war.
9The circumference of the shield is completely edged with plumes attached individually to vegetal-fiber strings. Four such strings, colored blue, green, and red are tied together and sewn to the base. This kind of attachment and the various colors of the individual feathers create a delicate decorative edging which gently moves at the slightest breeze of air.
10Along the lower edge of the shield there are on both sides a number of feather tassels made from rose-colored spoonbill feathers and measuring about twenty centimeters in length. At their distal ends there are small cylinders of cotton fabric and paper to which are glued feathers of the same colors as those found in the feather edging of the shield.
11Because of its age and its eventful past, the condition of preservation of the feather shield has become very delicate. Of the pieces of sheet gold, some have disappeared over time, and a large portion of the feather tassels has likewise been lost. All over its surface the feather mosaic has become very sparse, and the feather fringe along the edge of the shield has already suffered severe damage. The damages caused by processes of oxidation, chemical decay, mechanical deformation, and not the least moth infestation are partly visible, but partly also invisible, especially in the most delicate portions of the feathers, the fine hooks which are responsible for keeping the feather vane together. Through the loss of numerous small feathers and the paling of the colors as a result of the exposure to light, the original colorful impression of the shield can now only be surmised.
12The attention given to the shield by conservation to this day has been exclusively one devoted to the preservation of the status quo, since any attempt at reconstructive restoration has been avoided for ethical and historical-documentary reasons. Each manipulation is seen as leading to a further loss of original substance and is therefore kept at the absolutely necessary minimum. Any loan request necessarily requires the object to be moved – it has to be taken from its climatized, dust-free case; it has to be moved for packing, transferred to its new venue, be unpacked again, and mounted in its new display case.
13All these steps will, of course, have to be taken as carefully as possible, but the object cannot be moved without causing some form of agitation. When opening the case in which the object had generally been for many years, the climate changes all of a sudden, even if only by several percentage points of relative humidity. In order to inspect the condition of the artifact, lighting has to be much stronger than the usual 50 lux, and the necessary photography with flash or flood light also contributes to a substantial increase of the ultraviolet and infrared impact. In order to protocol the existing damages, the object has to be turned over and around several times to look at it from all angles – and this happens four times during each loan. In the course of handling, pressure is exerted on the feathers, which may lead to new fractures of the sensitive parts of the feathers and to the possibility that glued pieces may come off the base.
14Packing has to be made in such a way that the object cannot move around and may thus be impacted at its edges. At the same time, no pressure must be exerted to the delicate feather mosaic on the shield's surface.
15After endless discussions we opted for a mode of packing in which the shield is attached exclusively by means of its relatively stable backside. The Viennese packing firm produced a box of so-called "kapa boards" consisting of a core of polyurethane hard foam lined with acid-free board, whose most important part was a two-layered sliding tray with an opening in its center; a coated metal mesh inserted between the two layers served to attach the shield to the tray: Through the opening of the tray, the shield was attached to the mesh by means of a twill band passing around the wooden sticks. The tray slides vertically in and out of the box and needs nothing else to be firmly fixed in it. By closing the box lid, the tray is fixed in the box at its four corners. The lid is made of the same material as the box and is attached to it by means of a Velcro fastener. Within the box, there is no need for filling material which might harm the sensitive surface by rubbing against it. The closed box is packed into a shock-absorbing, climatized box and is transported by an air-cushioned, fully climatized truck. On the way to London, it was decided to take the Eurotunnel under the Channel rather than the ferry. For me as the courier it was an interesting experience to sit in the driver's cabin on an especially cushioned seat and to feel every bump on the road in full consciousness of the fact that the object resting in its case on the loading platform didn't have such a seat. As a result, the moment of unpacking the shield was full of suspense. Surrounded by a crowd of colleagues from around the world who wanted to admire my distinguished freight, I was relieved to find that fortunately no visible damage had occurred.
16After the end of the exhibition in London, the feather shield had to undergo the procedures as described above for a second time. Despite all the stress imposed by these procedures (but also because of them), the shield has safely returned to Vienna and is presently kept in the museum storage in the box made for its transportation until the time of the reopening of the museum. Even if the present case may be seen as a positive example of the highest standards in the transportation of artifacts, the loan of such sensible pieces as the Aztec feather shield in Vienna will remain to be a highly questionable proposition in the future as well.
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Walter Baumgartner, « The Aztec Feather Shield in Vienna: Problems of Conservation », Nuevo Mundo Mundos Nuevos [En ligne], Colloques, mis en ligne le 01 février 2006, consulté le 23 janvier 2017. URL : http://nuevomundo.revues.org/1447 ; DOI : 10.4000/nuevomundo.1447Haut de page
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