**1. Introduction**

The experience of developed societies and those emerging today confirms the primacy of culture over development [1]. Cultural mastery unleashes the creative energies of development through art, mainly African art which integrates the three elements of the universe: nature, human and the divine. This art does not target the isolated individual, but the integrated person, deeply united with the group and the community. In fact, inventing sustainable development involves building a new cultural vision based on scientific research. Indeed, the dyes used in the making of heritage works represent a cultural element of the first order [2]. In all parts of the world, natural dyes have been used since time immemorial until the end of the nineteenth century, when they were dethroned by the discovery and economic development of synthetic dyes.

The organic compounds responsible for color in ancient materials were obtained from plants, insects, crustaceans and lichens [3]. In addition, the mineral substances used came from red or yellow colored earth, ... Their identification in the recipes formerly used in the confection of ethnic objects is important, not only as an indicative technical element, but it also promotes the knowledge of intentions artists, mixing or preparation systems, the quality of the pigments used, their origin and their supply points [2]. Therefore, it provides important information for the application of appropriate treatment in modern conservation-restoration interventions. In addition, beyond the recognition of simple artistic technicality, it contributes to the revelation of their cultural and cult reference.

The recurring problem with ethnographic collections is linked to the lack of documentation or its imprecision, particularly for objects collected in the past [4]. The example of the objects presented in this work is indicative of these shortcomings. However, it has been clarified, according to certain inscriptions and/or characteristics of representation, that these are objects collected around 1900 and coming from the Yoruba-Nago region currently located on the territory of the Republic of Benin. These objects belong to the collections of two museums located in the city of Lyon-France; it is about the African museum and the museum of Confluences. These objects are particularly important because beyond the esthetics, they were all intended for a specific use in their locality of origin. Indeed, the Guèlèdè masks, the Ibéji statuettes, the Shango or hunter costumes ..., worn during specific rituals, or other propitiatory ceremonies increase the spiritual vision of the wearer. This shows, in fact, that ethnic objects remain characterized by the genius of assembling or mixing materials, and moreover by the genius of the expression of matter and of the verb.

In recent decades, ethnic objects have gained value by circulating between galleries, auction houses and foreign museums; it is important to safeguard and enhance the objects of Beninese cultural heritage in this flourishing art market.

To this end, an ethnobotanical survey was therefore carried out upstream, with the aim of selecting as well as characterizing the coloring principles of the dye plants most used in South Benin in the making of artistic and craft objects [5, 6], followed by an analytical chemical study by Liquid Chromatography (HPLC-UVvisible), by infrared spectroscopy and *via* microchemical tests of dye materials taken from ancient ethnic objects, in order to identify their matrix origin [7]. Overall, this paper is a social and scientific contribution to the knowledge of natural dyes and materials historically used in the artistic field in Benin in order to improve and revive, ultimately, knowledge of traditional skills as well than for better conservation-restoration of heritage objects.

#### **2. Historical overview on ethnic objects**

We cannot separate the historical context of the chemical characterization of the materials formerly used by African artisans and artists in the making of cultural heritage objects, in particular with regard to the identification and the geographical origin of the objects that have been deported, sold or exchanged. Indeed, works of art from the African continent were formerly relegated to second place, calling them gross or magical. In 1898, the Great Encyclopedia affirmed that "Among the Negroes who seem, however, like all the races of central and southern Africa, very backward in matters of Art, we find idols representing men and reproducing with a grotesque fidelity the characters of the Negro race" [8]. This attitude of Eurocentric academics, which consisted in classing peoples according to their level of artistic technicality, can be explained for a reason which is twofold: the lack of written documents capable of allowing a study is the first; the second finds its foundation in slavery and colonization.

A few decades later, voices were raised against this mechanical determinism; this is the case of R. Andree cited by Laude (1988) [9]. The latter mentions in his book that in 1885 Andree wrote that: "Peoples situated at a lower degree of culture may have reached a relatively high degree in the field of art, [...] it does not appear not always as the highest state in the evolution of a people". It follows a material influx from Europe on the question of Negro art which generates more curiosity. Indeed, the Europeans will be interested in the products of the civilization of the negroes which they bought in mass and accumulated them in their museums. At the same time, some missionaries (SMA: Society of African Missions) collected these objects, most of which were described as fetishes and which they deported to Europe. This

**23**

presented in **Figure 1**.

(KSCN, 160 g L<sup>−</sup><sup>1</sup>

(K3[Fe(CN)6], 100 g L<sup>−</sup><sup>1</sup>

*Cultural Heritage Objects of Southern Benin: Plant Dyes and Exudates Used in Their Confection*

is the case in Benin of the Reverend Father Francis Aupiais. Indeed, a few years after the creation of the S.M.A (1856), the priest Auguste Planque asked the missionaries living in Dahomey to send: "*a collection of things from your new homeland. We want to have in our museum weapons, tools, household utensils, all your gods. In a word, everyday objects that are outside our customs*." [10]. In addition, the works were gathered to facilitate their study, their knowledge by everyone who could have business in Africa. It was the beginning of a very obvious predilection for descriptions and observations made of Negro art. As a result, today, the vast majority of objects of African heritage are found in European and North American museums. It is rightly so, that the materials characterized and/or presented in this paper, were taken from ethnic objects coming mainly from the museum of the service of the African missions (SMA) known under the name of the African museum of Lyon and whose did not have information as to the materials mainly, the dyes used in their manufacture.

**3. Methodological approach and principle of the physico-chemical** 

The success of a heritage approach requires a preliminary or even permanent interaction with the holders of endogenous knowledge and skills. To this end, an ethnobotanical study was carried out on the materials historically used in the making of cultural heritage objects in the region of southern Benin [6]. The target of this survey was mainly aimed at artisans and artists as well as resource persons invested in local cultural awareness. This is a survey based on a semi-structured interview, followed by demonstration sessions on the use of natural materials used by the craftsman, as well as their harvesting for analytical purposes. The analysis plan used is based on a succession of physicochemical analysis techniques which consist in promoting, at each stage, the choice of the appropriate method for the rest of the analysis. This procedure made it possible to reduce the number of experiments to be carried out on the samples taken while increasing the quality of the results obtained. Indeed, very small quantities of dye material the size of a pinhead, are taken from the sampled objects. Then, using a binocular magnifier, the pigments are sorted in order to have the best homogeneous material which is analyzed using an infrared Fourier transform spectrometer (IR-TF) [7]. The interpretation of the results obtained, and their comparison to direct witnesses or to the IR-TF database, conditions the choice of the following analysis. Thus, the coloring matter undergoes either microchemical tests to complete or confirm the results derived from the IR for the inorganic compounds, or an HPLC analysis with a view to identifying the organic dyes. The schematic summary of the sample analysis plan is

The IR-TF analysis consists in preparing translucent KBr pellets from the materials taken from the objects, which are subjected to the beam of a spectrometer (Nicolet AVATAR Thermo-360 FT-IR, DTGS KBr detector/OMNIC treatment version 6.0/ acquisition of 64 scans). Colored textiles are directly subjected to the infrared beam in ATR mode. IR-TF spectra were collected in the mid infrared (400–4000 cm<sup>−</sup><sup>1</sup>

Microchemical analysis consists in highlighting the constituent ions of mineral pigments. It is carried out by the wet route in a drop of solution under a binocular magnifier. The detection of iron(II) was carried out by reaction with thiocyanate

[11]. That of iron(III) was confirmed by reaction with potassium ferricyanide

S2<sup>−</sup> was visualized in an acid medium by reaction with the addition of the reagent iodine-sodium azide and that of the Al3+ ions by the addition of the acetic buffer and

) in an acid medium according to the conventional protocol

) in an acid medium [12]. The presence of the sulfide ions

).

**analysis plan for materials taken from museum objects**

*DOI: http://dx.doi.org/10.5772/intechopen.91294*

*Cultural Heritage Objects of Southern Benin: Plant Dyes and Exudates Used in Their Confection DOI: http://dx.doi.org/10.5772/intechopen.91294*

is the case in Benin of the Reverend Father Francis Aupiais. Indeed, a few years after the creation of the S.M.A (1856), the priest Auguste Planque asked the missionaries living in Dahomey to send: "*a collection of things from your new homeland. We want to have in our museum weapons, tools, household utensils, all your gods. In a word, everyday objects that are outside our customs*." [10]. In addition, the works were gathered to facilitate their study, their knowledge by everyone who could have business in Africa. It was the beginning of a very obvious predilection for descriptions and observations made of Negro art. As a result, today, the vast majority of objects of African heritage are found in European and North American museums. It is rightly so, that the materials characterized and/or presented in this paper, were taken from ethnic objects coming mainly from the museum of the service of the African missions (SMA) known under the name of the African museum of Lyon and whose did not have information as to the materials mainly, the dyes used in their manufacture.
