TZAUHTLI

1The nahuatl word tzauhtli is used to name the gum with adhesive properties, obtained from the pseudobulbs of several species of orchids, which was used in Mexico as the adhesive for feather mosaics during Pre-Columbian and Colonial times.

ORCHIDS

2The family orchidaceae is divided into 6 subfamilies, over 725 genera, and approximately 25,000 species. According to the botanical system for naming plants, orchids are given a basic name of two units – a genus and a species name. Thus, Laelia autumnalis refers to only one specific kind of orchid. The first name – Laelia – indicates that this orchid belongs to the genus Laelia, which comes from the American Continent, mainly form Mexico, Central America and Brazil. In Mexico, 11 species of Laelia have been identified.

3Orchids are found in nearly all parts of the world from the artic regions to the tropics, although it is in the warmer areas where they are most plentiful, in number and forms. Although many orchids, especially in the artic and temperate regions, grow in the ground and are thus terrestrial, the majority, in tropical and subtropical areas, grow attached to trees or on rocks and are called epiphytes (see figure 1). Orchids are not parasites, the grow on the trees, attached to the roughness of the bark and absorbing the moisture in it.

4Water and nutrients are stored in the orchid’s pseudo-bulb as gums, which are polysaccharides. Pseudo-bulbs are not roots but hypertrophied stems.

ORCHIDS AND TZAUHTLI

5In the 16^th century vocabulary by Alonso de Molina, tzauhtli is translated as the Spanish word engrudo, strictly meaning “starch paste”. Bernardino de Sahagun, described in the 16^th century the manufacture of several kinds of feather-work; the word tzauhtli is usually translated as pegamento (glue or adhesive) or engrudo. Dr. Francisco Hernandez, who traveled to New Spain in 1570, refers to tzauhtli as gluten, and describes, sometimes accompanied by drawings, the plants used to extract tzauhtli.

6Sahagun and Hernandez are the only first hand sources I have found about the use of tzauhtli in the 16^th century, at the time of the Spanish arrival to Mexico. (However, I’ve heard that Diana found a third Colonial reference of tzauhtli).

7In the 19^th century, Pablo de la Llave and Juan Lexarza made a botanical classification of de descriptions by Hernandez, and it is thanks to their work that we know that tzauhtli was obtained form orchids. Most of the authors who have written about tzauhtli in the 19^th and 20^th century use the names given by de la Llave and Lexarza. However, during the 20^th century, the taxonomical classification of the orchids has changed.

LA LLAVE Y LEXARZA	OTHER SCIENTIFIC NAMES
Arpophilum spicatum
Bletia autumnalis	Laelia autumnalis (Llave y Lex) lindl.
Bletia campanulata	Bletia reflexa Lindl from other authors
Bletia coccinea	Bletia fulgens Reich. F.
Bletia grandiflora	Laelia speciosa (H:B:K) Schltr. Laelia grandiflora (Llave y Lex) lindl. Laelia majalis Lindl.
Cranichis speciosa	Not determined. Probably a Spiranthinae
Cranichis tubularis	Not determined. Probably a species now named Deiregyne pyramidalis
Epidendrum pastoris	Encyclia pastoris (Llave y Lex) Schltr Encyclia venosa (Lindl.) Epidendrum venosum Lindl.
Maxillaria liliacea	Govenia liliacea (Llave y Lex) Lindl.
Maxillaria superba	Govenia superba (Llave y Lex) Lindl. Ex Lodd
Sobralia citrina	Cattleya citrina (Llave y Lex) Lindl. Encyclia citrina (Llave y Lex) Dressler.

8In the column at the right we have the botanical names given by de la Llave and Lexarza, in the left column we have other scientific names. The correct taxonomical name used in 1996 is given in bold characters.

SCIENTIFIC NAME	COMMON NAMES
Arpophilum spicatum	Tsauxilitl Tzauxilotl
Bletia campanulata	Flor de muertos Chautle Huararichiri-tsitsiki (tarasco) Sautle Saucle Tsacuitli Tsacuxochitl Tzautle Tonalxochitl
Bletia coccinea	Tzacuxochitl Arorácua (tarasco)
Laelia speciosa	Flor de corpus Flor de mayo Itzamahua Juritzaquiri-tzitzica (tarasco) Flor grande Tlacuxochitl Deantza (otomí)
Cranichis tubularis	Acatzauhtli Tzauhtli
Enclycia citrina	Azucena amarilla Costicatexochitl Costictexochitl Cozticoatzontecotxochitl Flor de huevo Tatzingui (tarasco) Acatl-tzauhtli
Encyclia pastoris	Amatzauhtli Saucle Tzacutli
Govenia liliacea	Azucena del monte Icahueyo Iztactepetzacuxochitl Petzacuxochitl Petzanxohitl Costiczacatzacuxochitl
Govenia superba	Azucena amarilla Azucena del monte Costiczacatzacuxochitl Costictepetzacuxohitl
Laelia autumnalis	Ahoatxochitl Ahuasuchitl Ahuaxochitl Diegos Flor de animas Flor de muertos Flor de santos Lirio de San Francisco Chichitictepetzacuaxochitl
Cranichis speciosa	Atzauhtli Chautli Flor de corpus Tzacuxochitl Zautle

9The common names of the orchids according to Maximino Martinez (1979) are listed here.

10Some authors say that certain species of orchids had better adhesive properties than others, or than a couple of species were most commonly used to prepare tzauhtli. From the 11 species of orchids mentioned by Hernandez, apparently those used more often were, first of all Epidendrum pastoris (Encyclia pastoris) followed by Bletia campanulata and Bletia autumnalis (Laelia autumnalis).

BLETIA CAMPANULATA

11Hernandez’s tzacuxochitl is classified by de la Llave and Lexarza as Bletia campanulata, a terrestrial orchid. During winter the pseudo-bulb is hidden under the ground. By the end of the spring the first leaves appear, and are very similar to grass. It flowers during the rainy season, in July or August. It has an erect spike with 3 or 4 flowers, purplish pink petals and a white lip. This orchid is found in Mexico, Central and South America.

LAELIA AUTUMNALIS

12De la Llave and Lexarza described this species as Bletia autumnalis, but it is now known as Laelia autumnalis. This is an epiphyte orchid, with a green and oblong pseudo-bulb, about 15 cm long and 3 cm wide, hard and fibrous, wrinkled length-wise and 1-3 leaves, It has an erect spike wit 5 to 12 flowers, from 7 to 10 cm. Petals are purplish pink with a lip slightly rolled, and darker. It flowers during fall, form September to November. This orchid is typical of the Mexican mountains, growing at 1800-2700 meters of altitude.

13Hernandez called this plant chichiltictepetzacuxochitl. (See figure 2)

EPIDENDRUM PASTORIS

14The epidendrum pastoris described by de la Llave and Lexarza is an epiphyte orchid, with 2 or 3 oblong leaves, with yellowish flowers with purple lines and a white lip. It flowers in June and July. There were doubts in the past about the classification and identification of this orchid, but it is very probable that it is the former Encyclia venosa, now Encyclia pastoris.

15The 16^th century drawing of amatzauhtli by Hernandez was erroneously given the name of Epidendrum pastoris, (see figure 3) but apparently this drawing represents an Encyclia concolor. Urbina (1903) states that the orchids called tzacuhtli and amatzauhtli by Hernandez are both Epidendrum pastoris, however, the drawings depict different plants.

16It is quite unfortunate that the orchid most commonly mentioned in literature as producing the best tzauhtli cannot be easily identified.

ENCYCLIA CITRINA

17The plant named costicoatzontecoxochitl by Hernandez was classified as Sobralia citrina by de la Llave and Lexarza; it was called Cattleya citrina later, and now the name Encyclia citrina is used. The purepechas of Michoacan use the word tatzingui to name the orchid and the adhesive extracted form it. Apparently tatzingui was used in the same way as tzauhtli. We know that many other orchids were traditionally used to extract adhesives, in Mexico and all over the world.

PREPARATION OF THE GLUE

18The first step is to collect the pseudo-bulbs. The pseudo-bulbs of epiphyte orchids are easily recognized on the trees (see figure 4), however the pseudo-bulbs of terrestrial orchids are hidden under the ground, and it is not easy to recognize the plant unless it has flowers. The pseudo-bulbs are washed to eliminate the soil and dirt. Apparently, there were three different methods to prepare the adhesive.

19The first method was to cut or crush the pseudo-bulbs, this was sun-dried and then ground. This dry powder of tzauhtli could be stored. Tzaulhtli was sold as a powder at the open market in Tlatelolco. Prior to use, the powder was dissolved in water. This is the only method mentioned in 16^th century sources.

20(Florentine Codex. Book ten: The People. Twenty fourht chapter).

21The glue seller, the digger of glue plant [roots] digs glue plant [roots], beats them with a stone, pulverizes them. He sells glue plant [uncooked] –pulverized, ground. [The evil glue seller sells glue] coarsely ground, with pulverized maize stalks, with ground grains of maize, with ground beans.

22The second method was to cut the pseudo-bulbs into small pieces and cook them in water. In this way, the gum was liberated into the water.

23The third method was to use the adhesive directly from the pseudo-bulb. When the pseudo-bulb is cut, it segregates a small amount of gum.

24I have also herd that Diana found a colonial reference to a fourth method of preparation of tzauhtli.

25Pseudo-bulbs store nutrients in the form of polysaccharides. The tzauhtli obtained using the last two methods is a vegetable gum. However, the tzauhtli obtained with the first method of preparation will contain other elements besides the gum, such as cellulose fibers and starch. Cellulose and starch are insoluble in water but starch will suspend in water to form starch paste when cooked. Although the amount of starch in pseudo-bulbs is small, around 7%, the amount of fibers can be considerable, depending on the species, being larger in epiphytes. This will lead us to think that the tzauhtli obtained from powdered pseudo-bulbs will be more like a paste or putty rather than a gum.

26Colonial sources never mention if tzauhtli powder is mixed with cold or warm water, nor if the mixture should be cooked to obtain the adhesive. However, the fact that Molina translates the word tzauhtli as engrudo or starch paste must be taken into account.

TRADITIONAL USE OF TZAUHTLI.

27Tzauhtli was used as an adhesive for paper, maybe in the manufacture of three-dimentional paper figures, some sort of elaborated origami, which have been found in offerings buried at Templo Mayor.

28It was also used as an ingredient of the corn paste used to model light weight sculptures. It is known that both Aztecs and purepechas used to manufacture sculptures using corn paste, and the technique was then used during Colonial times for Catholic representations.

29We know tzauhtli was used as a binder for tempera paintings, but 16^th century authors do not mention if it was used for codices, wall paintings or other kind of painting.

TZAUHTLI AS ADHESIVE IN FEATHER MOSAIC

30Florentine Codex. Book Ten: the people. Seventh Chapter.

31The feather-worker [is] accomplished ingenious, meritorious of confidence, of trust. He practices the feather-worker's art; he glues, he arranges [the feathers]. He arranges different colors, takes measurements, matches [feathers].

32The bad feather-worker[is] hypocrite, a destroyer of good work --headless of others, dull, uncouth. [He is] stupid, torpid. He can do nothing; he harms, damages, wastes [feathers].

33Florentine Codex. Book Nine. Twenty-first chapter. (See figures 5, 6, and 7)

34The feather workers, who painted with feathers, who rejoiced in feather [work], thus began their creations. First of all, they saw, by the pattern, how they could make it. They who first drew it were the scribes.

35When they had seen how it was designed, that it was well done, that the painting was sufficiently detailed, then on a maguey leaf they reinforced cotton: they strengthened it with glue. They called this the reinforcement of cotton.

36They sought a good [maguey leaf], of smooth, shiny surface, with no knobs; and even, not raised [or] depressed. On it they reinforced the cotton.

37First they put glue on the surface; with their hands they covered the surface with glue. Then on this they laid, they stretched out, they pressed down the carded cotton. First they carded it well; they stretched it repeatedly; they thinned it out. When this was just like a cobweb, like the mist, they pressed it down upon the maguey leaf, and set it out in the sun. Only a little did the surface dry. When the surface had dried, once again they spread glue on the surface, thereby making the surface of the cotton glossy, shiny. So no more was to be carded, since the glue was well hardened on it.

38And when it had dried, when it crackled with its dryness, then it was peeled off. Then [the cotton] was spread, placed on the painted pattern. On [the cotton] was painted, delineated, on it one went tracing, the painting which appeared from underneath.

39And when finished, when the cotton was painted all over, when nothing of all the completed pattern had been forgotten, then [the cotton] was glued on a piece of paper, coarse paper, so that [this] reinforced cotton was completely strengthened, so that it was given support. And then was started the trimming, the gouging, with a metal blade where [the outline of] the painting was projecting [or] was drawing in. It was cut, trimmed, on a small piece of wood called a cutting board. All was cut on this; feathers were broken, evened off, rounded off at the top.

40And when the paper pattern had in all parts been trimmed to be like the [original] painting, then it was spread out upon a maguey leaf; on this was traced the pattern which had been cut.

41When the maguey had been painted, then it was covered with glue; cotton was applied to it; thereby the [second] reinforcement of cotton was strengthened with glue. The outline of the painting was put on it. Again it dried in the sun. Later, upon it were placed, one by one, the feathers called “the glue hardened ones”, those which had been glued, dried.

42But first, quite apart, on a maguey leaf, the feathers had been cut, one by one; glue hardened, one by one. They were known as the glue hardened feathers. The feathers were suspended, dipped, in glue; later they were stuck to the maguey leaf; their surfaces were smoothed with the bone blade.

43The so-called glue hardening was all of common feathers; for they came first of all, at the start, in order to accomplish the feather work. This, to begin with, became the basis, the bed, on which all the precious feathers were bedded. Perhaps yellow dyed ones were glue- hardened, or heron, or scarlet ones, or blue parrot, or green parrot feathers, or some feathers dyed in one color, dyed in many. They took note, they tried out, they matched whatsoever kind would harmonize, would serve as the basis for the precious feathers. Blue cotinga were provided blue parrot feathers as a basis; they [also] matched scarlet macaw feathers. And for the trogonorus, they used green parrot feathers as a basis. ...

44These feathers, which were called yellow dyed, were only dyed; tinted yellow. The yellow color cooked in the fire; it boiled; alum was added; and then it was provided with saltpeter.

45When [the color] had been provided with saltpeter; when [the feather base was] finished; when on all parts stood the glue-hardened feathers for the basis; when everywhere each one had been laid out on the painted cotton on the maguey leaf, had been glue- hardened, then it was lifted off.

46And then a thin board was set out, a paper was glued on it: on this once again was painted the trimmed pattern, which had become the work design. On this was the feather-work completed on it all the feather base was glued, perhaps to be pictures of flowers, or of plants, or of some image which was to be made, or whatever design which was pleasing.

47When the pattern on the board had been painted, when it had been outlined, then began the gluing, the arranging.

48First the glue was dissolved, mixed. There was dissolving, making of glue. The preparation of the glue was the task of the children who were been trained. They dissolved the glue for [the workers]; they dissolved the glue. (See figure 7)

49Then the black outline was cut away in order to mark, to delineate, the feather painting, This came at the very beginning. First the [outline] feathers were glued, pressed on with the bone blade. The black outline was made of grackle feathers, or scarlet ones, the glue-hardened scarlet feathers. Then followed the cutting of its bed of glue-hardened feathers, which became the bed of the feathers according to the kind of feathers with which they first began, according to the pattern: perhaps the blue cotinga, or trogonorus, or red spoonbill, ...One by one they went matching the [precious] feathers, each being placed in position according to its appearance, as it glowed, shimmered. The mentioned glue-hardened feathers formed the bed in all places. They continued consulting the pattern, how it was painted, noting the different colors appearing on it.

50When the glue hardened feathers had been fastened down with the bone blade, then on its surface were set the precious feathers. Going placed, glued in order, set in position by means of the bone blade; just so proceeding to cover the glue-hardened ones. And on it the trimmed paper pattern went being laid, being tested. Lest somewhere the work may be warped, lest it be distorted, the pattern went on being compared as the gluing of the feathers proceeded.

51Just so was made, completed, the feather painting which was made with glue.

CHARACTERIZATION OF TZAUHTLI.

Extraction

52The mucilage was extracted from the pseudo-bulbs of Bletia campanulata. The pseudo-bulbs were cut into small pieces, distilled water was added, and the mixture heated to 54ºC for 15 minutes. The solution was cooled at room temperature and lyophilized in order to avoid decomposition.

53Lyophilized tzauhtli was analysed by FT Infrared Spectroscopy. As expected, the peaks in the spectrum correspond to a polysaccharide.

54Analysis by high temperature capilary gas chromatography.

55The difference between this analysis and the one regularly carried out for binders is that we used a programmed temperature on the chromatograph. Besides the regular analysis of monosaccharides after total hydrolysis, we also obtained the free sugar composition without hydrolysis and the oligosaccharides profile after partial hydrolisis. The details of this experiments are described else where.

Results and discussion

56The analysis of free sugars revealed the presence of fructose, glucose and high concentrations of saccharose. The monosaccharides identified after total hydrolisis were fructose, and high concentrations of glucose. This profile of manosaccharides including galactose is common to different mucilages after total hydrolysis. Therefore this analysis is not good enough for characterization and identification of the mucilage.

57It was observed that the concentration of the oligosaccharides changes as a function of time; therefore better results were obtained under mild conditions of hydrolysis (sulfuric acid 0.05M, 2h reaction time). The peak shape and resolution of monosaccharides and oligosaccharides up to DP3 (degree of polymerization) are good. Gum Arabic, tracacanth gum and nopal mucilage were analyzed under the same conditions as orchid mucilage in order to obtain their oligosaccharides profiles. As expected, each one was different. Therefore the HT-CGC analysis of oligosaccharides of the mucilage obtained after partial hydrolysis allows the characterization and identification of different gums and mucilages.

IDENTIFICATION OF TZAUHTLI ON A FEATHER MOSAIC

58Samples were taken from a feather mosaic in order to determine if the adhesive used to bind the feathers to the paper support was tzauhtli. The feather mosaic, San Francisco en Oracion, (30 x 20 cm) belongs to the Museo Franz Mayer, and is dated as 16^th-17^th century.

59Comparison of the oligosaccharides profile of the feather mosaic after partial hydrolysis with the tzauhtli profile reveals the possible presence or orchid mucilage, tzauhtli, as a binder in the sample. However, the small amount of sample limits our scope for repeating the analysis in order to confirm the result.