**1. Introduction**

The production of corn (*Zea mays* L.) stem light sculptures in New Spain (today Mexico) during the 16th and 17th centuries is a clear example of the convergence of two artistic traditions. On one hand, there are the Mesoamerican sculptural materials such as maize stems, agave inflorescence (*quiote*), and *colorín* wood (*Erythrina coralloides* DC.). On the other there are the European artistic traditions and iconographic models [1,2]. This technique is still used today in the Michoacán state (Western Mexico). Corn, the most characteristic material of this sculpture technique, was, and still is today, an important element in the Mexican culture. For example, according to the Mayan tradition, humankind was made of corn [3]. However, this type of sculpture was not exclusive to the New Spain viceroyalty. Bruquetas [4] reported examples of similar statues, made with glued fabrics and agave inflorescence, from the Andean region (previously the Peru viceroy). There are also historical records of the use of maize stem for sculpture production in the Kingdom of Guatemala [5].

It is possible to track the artistic tradition of American low weight sculptures through the Spanish *papelón* [6] until the Italian *cartapesta* [7] used at least since the 14th century as a profitable activity for artists thanks to an early serial production system of sculptures sold at lower prices due to the "poor" materials used. Because of the international trade routes of materials, such as gold, silver, and cochineal [8,9], as well as artwork during the Spanish Empire (16th–19th centuries) [10,11], some American light weight sculptures

**Citation:** Quintero Balbas, D.; Sánchez-Rodríguez, E.; Zárate Ramírez, Á. Holy Corn. Interdisciplinary Study of a Mexican 16th-Century Polychrome Maize Stem, Paper, and *Colorín* Wood Sculpture. *Heritage* **2021**, *4*, 1538–1553. https://doi.org/10.3390/ heritage4030085

Academic Editor: Diego Tamburini

Received: 24 June 2021 Accepted: 26 July 2021 Published: 31 July 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

arrived in European countries such as Spain [12–14] and Croatia (previously the Republic of Ragusa) [10].

The chronicles written by the friars in charge of the evangelization of the indigenous populations reported the technical procedures to use maize stem as sculpture material. According to the historical records, the production of maize stem sculptures started with the harvest of the adult maize plant after the production of the corn, followed by the cleaning of the stems, debarked or not according to their use, by boiling them. Finally, they were let to dry slowly. In some cases, the sculptors added poisonous plants to the boiling bath to increase the resistance to biological attack [14]. The debarked stems were ground and bound with a natural adhesive to prepare the paste for modeling the volumes. The historical references indicate the use of a polysaccharide gum named *tatzingueni* or *tzauhtli* extracted from orchid bulbs [15], but so far only animal glue has been identified in the sculptures analyzed [16].

Unfortunately, today, we know the name of very few artists that used maize stems and other local materials such as *colorín* wood. The Cerda family, Matías and his son, Luis, active during the 16th and 17th centuries in the Michoacán region (Western Mexico), are the most famous sculptors of which we have historical records [1,17,18]. Additionally, the sculpture of the *Virgen del Pueblito* (today in Querétaro state in central Mexico) is attributed to the friar Sebastián Gallegos (active during the first half of the 17th century), who probably learnt the technique in Michoacán [19]. There are also records about the use of maize stem by the friar Félix de Mata in Guatemala [5].

Despite the reduced records about artists, the technical and formal characteristics of the sculptures allow their classification into "workshops" linked to specific regions. Amador Marrero [13,20] proposed nine workshops associated with three geographical areas: the western area of Mexico, specifically, what is today the Michoacán state, the central area concentrated in Mexico City, which was the capital of the New Spain viceroyalty, and Oaxaca in the southwest region (Figure S1).

In addition to their formal characteristics, in general, the internal structure of the sculptures allows their classification; the examples from the Michoacán region have a core made of maize stem which is attached using natural fibers or light wood (e.g., *colorín*) covered with debarked maize stem and maize stem paste. On the other hand, the sculptures produced in the central area are hollowed. Artists used two-half casts to obtain the initial shape, made of paper (similar to the *papelón* or *cartapesta* techniques) and, in some cases, codices [14,21]. To facilitate the removal of the paper from the mold, the artist applied gypsum or diatomaceous earth [22]. This system allowed a semi-serial production of the sculpture [14]. The artists achieved the final volumes by modeling debarked or maize stem paste over the paper or wooden core.

The polychrome sculpture production was a collaborative work as dictated by the regulations of the guilds; after the sculptor finished the volumes, a polychromer (a specialized painter) prepared the polychromy [23–25]. Very few records report on the polychromy technique used in the maize stem sculptures. Bonavit identified the use of a preparation layer called *ticatlali* or *tízar* (most probably gypsum), which was also reported by Carrillo y Gariel [21]. Regarding the pigments, Bonavit suggested the painters used carbon black and cochineal lake mixed with a siccative oil as binder [26].

The scientific investigation of maize stem sculptures is paramount for their correct identification, classification, and correct conservation. The variety of materials and the complexity of the structure make it necessary to use a multianalytic approach to understand the technology of these sculptures. Radiography [12,27] and computerized tomography [10,28,29] are the preferred technique for the non-invasive investigation of the internal structure. Endoscopy also offers this kind of information, but it is applicable only to hollowed sculptures that, due to their condition, allow the insertion of the camera [30]. Microscopic and spectroscopic methods enable the study of the polychrome surface [27,31,32]. The research published so far indicates that the artists followed the European tradition: gypsum and animal glue for the ground layer and pigments (e.g., lead white, azurite, vermilion, minium) mixed with siccative oils, and in a very few cases, animal glue, as a binder. There are also reports of the use of metallic leaves applied over red bole to decorate the loincloth [13,19,22].

Most recently, studies have focused on gaining a better understanding of the degradation mechanisms of maize stem as a sculpture material, particularly its physical properties linked to their preparation, by studying the mechanical properties and the resistance to biological damage according to the part of the stem used and the method of preparation [33].

This work presents an interdisciplinary investigation that covers the historical research, the stylistic analysis, and the technological study of a 16th-century maize stem sculpture, *el Señor del Santo Entierro* (Lord of the Holy Sepulcher). Before our study, scholars misclassified the sculpture and suggested it was a substitution of the original. We completed historical research together with a multianalytic examination, combining non-invasive and micro-invasive methods, using computerized tomography (CT) to understand the internal structure, optical and scanning electron microscopy (SEM-EDX), micro attenuated total reflection-Fourier transform Infrared (μ-ATR-FTIR) and micro-Raman (μ-Raman) spectroscopies for the study of the original polychrome surface and its modifications. We aimed to recover the statue history and study its technology to classify it correctly and help in its conservation.
