Article suitable for older students

Reconstructing Aztec Super Glues

5th Jun 2008

Professor Frances Berdan, expert on the Aztecs

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

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?

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.

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.

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).

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.

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.

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).

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).

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’).

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).

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.

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.

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.

• 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.

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

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.

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

Comments (4)

Ross Warner

1st Sep 2017

Hello. I am very intrigued by the subject of this article. I am an enthusiastic amateur craftsperson with a curiosity for traditional practices (especially those that can be practiced today without supporting polluting industries). I want to experiment with adhesives which are can be used without being reliant on petro- and other synthetic chemicals, and it appears gum would be the thing for me.
I wanted to ask if Professor Frances could recommend a gum which would be suitable for attatching a sole material (rubber) to a upper-sole material (leather) for a Tarahumara style Huarache sandal, which would not become rigid once set; a gum which would allow the sole to flex and mold with the foot as it interacts with the ground.
Any insight would be appreciated.
Thank you for sharing your inspiring work.

Frances Berdan

31st Jul 2016

The most common (and effective) orchids that we experimented with, and that were consistent with the sixteenth-century descriptions, were Govenia sp, and Laelia sp. As your reader mentions, there are a great many different types of orchids in Mexico, and although these are consistent with effectiveness and the early descriptions and images, others may also have been used. There is also a likelihood that they may have been mixed together. The Aztecs were a very practical and observant people, and they would have used whatever gums or gum combinations that were readily available, workable, and were strong adhesives.

Khangi Thateiyumni

21st Jul 2016

There are quite a few different orchid species on Mexico. What is the common and scientific name of the.species mentioned on the article? I skimmed it over a few times and saw no mention of the identification.

Mexicolore

Professor Berdan has kindly answered this for you - above.

Dave Giguere

15th Oct 2009

We have jade art that is composed of crushed jade mixed with what my father said was pine pitch then pressed into a mask, glyphs, and figurines. Had them since the 50’. This article sounds like what he described as the process. Hard to verify.

Professor Frances Berdan, expert on the Aztecs