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General Aztecs Maya Tocuaro Kids Contact 27 Feb 2017/12 Water
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Article suitable for older students

Professor Frances Berdan, expert on the Aztecs

Reconstructing Aztec Super Glues

This article has generously been specially written for us by Professor Frances Berdan, who is a member of our ‘Ask the Experts’ Panel.

Pic 1: Terrestrial orchids
Pic 1: Terrestrial orchids (Click on image to enlarge)

Glue. It’s all around you. I would guess that every one of you comes into contact with glues (or its results) every day. It’s on paper, books, wood, your chair, even your shoes. But what about the Aztecs? What did they use for glues (more properly called gums, since they came from plants)? And how well did they work?

Pic 2: Epiphytic orchid
Pic 2: Epiphytic orchid (Click on image to enlarge)

I am co-director of the Laboratory for Ancient Materials Analysis (LAMA) at California State University San Bernardino, along with Dr. David Maynard, a chemist. We have been working together, with many enthusiastic students, to identify organic remains on ancient artifacts, and to recreate the kinds of gums used by the Aztecs and their neighbors.

Pic 3: Identification of orchids from 16th century documents
Pic 3: Identification of orchids from 16th century documents (Click on image to enlarge)

The Aztecs used a lot of different kinds of sticky plant materials as gums, each of them fitting specific gluing needs. For example, they used gum from the “bat-excrement tree” to attach obsidian blades to war clubs, and acacia gum to mend broken pottery. The gummy roots of tecpatl plants were used to capture birds: the sticky roots (probably mashed up and mixed with water) were spread on the grass or sticks at the birds’ favorite drinking and dining spots, thus ensnaring the unwary birds. Also, different kinds of orchids were used as gums in their gorgeous feather mosaics, copal and pine resins in their beautiful jade and turquoise mosaics, and beeswax here and there. We have spent most of our time with orchids, copal, pine resin, and beeswax.

Pic 4: Preparing orchid gums: slicing (left), the sliced pseudobulbs (centre), and drying (right)
Pic 4: Preparing orchid gums: slicing (left), the sliced pseudobulbs (centre), and drying (right) (Click on image to enlarge)

Orchid Gums. Orchids are either terrestrial (they grow in the ground) or epiphetic (they dangle from trees and get their nutrients from the air). Orchid gums came from both types of orchids: from the roots of terrestrial orchids (See Picture 1) and from the pseudobulbs of epiphetic ones (Picture 2). Fortunately for us, some sixteenth-century writers (especially Francisco Hernández and Bernardino de Sahagún) provided us with descriptions and even illustrations of some of these plants, so we can at least tentatively identify them today (Picture 3).

Pic 5: More orchid gum preparations: grinding the dried roots (left), the ground up powders (top right), and mixing the powders with water to make the gums.
Pic 5: More orchid gum preparations: grinding the dried roots (left), the ground up powders (top right), and mixing the powders with water to make the gums. (Click on image to enlarge)

These same early writers left us some “recipes” for making orchid gums: essentially, you slice them up, dry them in the sun, grind them thoroughly into a powder, and then “make” them into the gum (this last part is a little vague, but then, look at any recipe book and you’ll find the same sort of thing (Pictures 4 & 5). We have “made” these gums by mixing the fine powders with water, and they work splendidly.

Pic 6: Mashing (left) and cooking (right) raw orchid roots
Pic 6: Mashing (left) and cooking (right) raw orchid roots (Click on image to enlarge)

Alternatively, some of the roots are quite juicy, and you can actually just mash them up, heat them, and apply them as a powerful glue (much as the Tarahumara Indians do today when making their musical instruments) (Picture 6). The early documents tell us that some orchids work better than others, and we have also found this to be the case. In general, gums made from orchid roots fare better than those made from pseudobulbs.

Pic 7: High-ranking Aztec officers with feathered costumes, banners, back devices and shields. Codex Mendoza, folio 67r.
Pic 7: High-ranking Aztec officers with feathered costumes, banners, back devices and shields. Codex Mendoza, folio 67r. (Click on image to enlarge)

The Aztecs sold the orchid powder in the markets, mostly to the fine featherworkers who made magnificent shields, headdresses, fans, banners, costumes and other ornaments (Picture 7) using ordinary feathers (like duck or turkey) and expensive tropical ones (like scarlet macaw and quetzal) (Picture 8). The featherworkers used the orchid gums to attach the feathers to cotton and paper backings (Picture 9), creating exquisite, shimmering mosaics. It was the job of the children to make the gums (Picture 10), so they had to be ready whenever the master artisan was ready with his design (the mixture hardens up fairly quickly). These gums have held up superbly, as seen by the few actual feather artifacts still in existence (Picture 11).

Pic 8: Precious tropical feathers paid in tribute to the Aztec rulers. Codex Mendoza, folio 46r.
Pic 8: Precious tropical feathers paid in tribute to the Aztec rulers. Codex Mendoza, folio 46r.  (Click on image to enlarge)

Copal and Pine Resins. When copal and pine trees are wounded (unintentionally or on purpose by humans), they discharge a sap to heal the wound (Picture 12). The Aztecs and their neighbors collected large amounts of these sticky saps. Copal was used mainly as an incense, in virtually all Aztec ceremonies, and is still used today for that same purpose (Picture 13). But it also provided a very strong adhesive, and was used along with pine resins by the stone mosaic workers who simply had to cook it up (although they had to work rather fast, as it does set up very quickly) (Picture 14).

Pic 9: Highly magnified feather attached to cotton backing. From the feather disc in the National Museum of Anthropology, Mexico City.
Pic 9: Highly magnified feather attached to cotton backing. From the feather disc in the National Museum of Anthropology, Mexico City.  (Click on image to enlarge)

While orchid gums are fine, delicate, and transparent, resin gums are thicker and darker (Picture 15). They are also very strong. In our experiments, we found that the gums are even stronger when copal and pine resin are mixed together (Picture 16), as on three of the Aztec turquoise mosaics in the British Museum (be sure to check out the fascinating book, ‘Turquoise Mosaics from Mexico’).

Pic 10: The children made the glue for the featherworkers. Sahagún Book 9: ill. 99.
Pic 10: The children made the glue for the featherworkers. Sahagún Book 9: ill. 99. (Click on image to enlarge)

Beeswax. Beeswax was another popular gum. The pre-Columbian beeswax was made by stingless bees, and some beekeepers in Mexico still raise these types of harmless bees today (Picture 17). To turn beeswax into an effective adhesive, one merely needs to heat it up, although we do know that it was also mixed with other materials (such as pine resin). We have identified beeswax as an adhesive on a feather disc, and also as a repair material on the death mask of (Maya) Lord Pakal of Palenque (ruled 615-683 AD).

Pic 11: Colour illustration of Aztec feather mosaic shield in the Museum für Völkerkunde, Vienna, Austria.
Pic 11: Colour illustration of Aztec feather mosaic shield in the Museum für Völkerkunde, Vienna, Austria. (Click on image to enlarge)

So, what about repairs? Imagine, you stagger back from a nasty battlefield, exhausted, dirty, bruised, scraped up, and your beautiful feather shield in tatters. It was given to you by the emperor for capturing enemy warriors in the last war, so you can’t just throw it away – it’s a treasured symbol of your status and your fierceness on the battlefield (PIcture 18). You need to repair it somehow. We know almost nothing about how repairs were made, or by whom. If the owner of the object was responsible for keeping it in shape, then perhaps beeswax was a popular choice: it was easily obtained, available in the markets, presumably cheap, and easy to manufacture. Probably anyone would be able to make beeswax into a serviceable adhesive.

Pic 12: (left) copal tree, (right) sap dripping from copal tree.
Pic 12: (left) copal tree, (right) sap dripping from copal tree.  (Click on image to enlarge)

Sources:-
• Hernández, Francisco, 1959: ‘Historia Natural de Nueva España’. 2 vols. Mexico City: Universidad Nacional de Mexico.
• McEwan, Colin, Andrew Middleton, Caroline Cartwright and Rebecca Stacey, 2006: ‘Turquoise Mosaics from Mexico’. London: The British Museum.
• Sahagún, Bernardino de, 1950-82: ‘Florentine Codex: General History of the Things of New Spain’ (Arthur J.O. Anderson and Charles E. Dibble, transl. and eds.). Salt Lake City: University of Utah Press.

Pic 13: Copal being sold in the market at Tepoztlan, Mexico.
Pic 13: Copal being sold in the market at Tepoztlan, Mexico. (Click on image to enlarge)

Picture sources:-
• Picture 1: Photographs by Frances Berdan
• Picture 2: Photograph by Frances Berdan
• Picture 3: (a) Hernández 1959, vol. I:119; (b) Sahagún 1950-82, Book 11: ill. 665; (c) and (d) photographs by Frances Berdan.
• Picture 4: Photographs by Frances Berdan
• Picture 5: Photographs by Frances Berdan
• Picture 6: Photographs by Frances Berdan
• Picture 7: Codex Mendoza image scanned from our copy of the James Cooper Clark 1936 facsimile edition, London; the original codex is in the Bodleian Library, Oxford.

Pic 14: Cooking copal resin into a gum.
Pic 14: Cooking copal resin into a gum. (Click on image to enlarge)

• Picture 8: Codex Mendoza image scanned from our copy of the James Cooper Clark 1936 facsimile edition, London; the original codex is in the Bodleian Library, Oxford
• Picture 9: Micrograph by Frances Berdan
• Picture 10: Florentine Codex image scanned from our own copy of the Club Internacional del Libro 3-volume facsimile edition, Madrid, 1994; the original is in the Biblioteca Medicea Laurenziana, Florence, Italy
• Picture 11: illustration by Miguel Covarrubias, scanned from our copy of his book ‘Indian Art of Mexico & Central America, Borzoi Books, Alfred Knopf, New York, 1957, page 292
• Picture 12: Photographs by Frances Berdan
• Picture 13: Photographs by Frances Berdan
• Picture 14: Photograph by Frances Berdan.

Pic 15: Experimental use of copal as an adhesive. Jadeite chips are attached to Cedrela Odorata wood.
Pic 15: Experimental use of copal as an adhesive. Jadeite chips are attached to Cedrela Odorata wood.  (Click on image to enlarge)

• Picture 15: Photograph by Frances Berdan
• Picture 16: Image by Frances Berdan
• Picture 17: Photographs by Frances Berdan
• Picture 18: Photograph by Frances Berdan.

Pic 16: Relative strengths of Aztec gums. In our tests, the strongest gums were from a terrestrial orchid, Govenia sp. Copal and pine resin combinations were stronger than either copal or pine resin alone.
Pic 16: Relative strengths of Aztec gums. In our tests, the strongest gums were from a terrestrial orchid, Govenia sp. Copal and pine resin combinations were stronger than either copal or pine resin alone.  (Click on image to enlarge)

Dr. Frances Berdan, Professor of Anthropology and Co-Director of the Laboratory for Ancient Materials Analysis at California State University, San Bernardino (USA), specializes in ancient and contemporary Mesoamerican cultures, with a special emphasis on the Aztecs; Mesoamerican codices and writing systems; cultural anthropology; economic anthropology. She has conducted archaeological fieldwork in New Mexico, ethnohistorical research in archives in Mexico and Spain, and ethnographic fieldwork in indigenous villages in eastern Mexico. She also engages in experimental reconstructions and identifications of archaeological materials, most recently focusing on adhesives and pigments.

Pic 17: (1st photo) Beeswax produced by native stingless bees, (2nd. photo) native beeswax (left) compared with Africanized beeswax (right).
Pic 17: (1st photo) Beeswax produced by native stingless bees, (2nd. photo) native beeswax (left) compared with Africanized beeswax (right). (Click on image to enlarge)

Our sincere thanks are due to Professor Berdan for this splendid contribution to our website.

Pic 18: Aztec feather shield in Chapultepec Castle, Mexico City.
Pic 18: Aztec feather shield in Chapultepec Castle, Mexico City.  (Click on image to enlarge)

This article was uploaded to the Mexicolore website on Jun 05th 2008

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Mexicolore replies: Professor Berdan has kindly answered this for you - above.