10.6092/issn.1973-9494/7937
The study and research described in this paper aims to reveal the unexplored aesthetical role of colors used for the ceramics in a mosque from the Marinid dynasty in Tlemcen, Algeria. The methodological approach consists firstly, of a formal analysis of the mosque’s artwork by describing its elements and composition and related principles.Secondly, the patterns and geometries are analyzed in-depth using artistic color concepts and laws of color contrast. The analysis demonstrates that the contrasts between bright, pure and dynamic colors provide luminosity, dynamism, rhythm, brightness and an optical mix. The color contrasts are also found to provide visual illusions of mass, volume or movement, as well as depth and relief that ultimately result in influencing the overall ambience of the mosque. The study thus enables the chromatic authenticity of this architectural heritage to be preserved by providing the necessary data for potential conservation, as well as providing a basis for innovative principles in expressing contemporary architecture.
application/pdf
1973-9494
7937
en
Kheira Tabet Aoul
Conservation Science in Cultural Heritage
Marinid heritage
Polychrome ceramics, artistic diagnosis and resulting ambiances in a Marinid Mosque, Algeria
Text.Serial.Journal
https://conservation-science.unibo.it/
17
Articles
2018-03-28
2018-03-26
2018-03-28
2019-09-06
27-44
CSCH
Kheira Tabet Aoul
2017
10.6092/issn.1973-9494/7937
27
Department of Architectural Engineering, College of Engineering, United Arab Emirates University, Al Ain
1973-9494
Marinid heritage
en
44
Ringgenberg, P. (2009). <em>L’univers symbolique des arts islamiques</em>. Paris: L’Harmattan.
Polychrome ceramics, artistic diagnosis and resulting ambiances in a Marinid Mosque, Algeria
https://conservation-science.unibo.it/article/download/7937/7653
17
P    OLYCHROME CERAMICS, ARTISTIC DIAGNOSIS
     AND RESULTING AMBIENCES IN A MARINID MOSQUE,
     ALGERIA

   Meriem Benkhedda
   Département d’Architecture, Université des Sciences et de la Technologie d’Oran
   Mohamed Boudiaf, USTO-MB, Oran, Algeria

   Kheira Tabet Aoul*3
   Department of Architectural Engineering, College of Engineering, United Arab
   Emirates University, Al Ain, United Arab Emirates


   Keywords: ambience, ceramic, color, Marinid heritage


   1. Introduction

    Architectural heritage carries inluential, powerful, symbolic, aesthetic and visual
dimensions, inherently essential to the cultural identity of a people [1]. A sustainable
approach to architectural heritage starts with its acknowledgment, documentation and
preservation. Furthermore, this approach may enable architectural heritage to act as a
vehicle for interpretation in contemporary design.
    Algeria, in North Africa, is a land of rich and diversiied architectural heritage built
by its successive occupants; they included the Phoenicians, the Romans, the Arabs,
the Spanish and the Ottomans and concluded with the French [2, 3]. In this context,




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
the city of Tlemcen, located in the northwestern part of Algeria, remains one of the few
places that still houses major representative monuments of Islamic art in Algeria. Its
proximity to Spain and Morocco explains the presence of numerous vestiges whose
architecture attests to a thriving art production [4]. Marcais [5, 6] documented the Arab
monuments in Tlemcen, highlighting the valuable architectural heritage of the great
royal city remains but, at the same time, stressing the need to preserve them.
    The city of Tlemcen owes its Islamic heritage to its successive dynasties: the Al-
moravids (1040-1147 CE), the Almohads (1121/1147-1269), the Zayyanids (Abdelwa-
dites) (1235-1556), and most particularly the Marinids (1248/1269-1465) who excelled
in the art of faience mosaic [7-10]. Tlemcen’s main monuments, which span the period
from the thirteenth to the middle of the fourteenth centuries, have often been compared
to the Andalusian monuments of Granada in Spain [11].
    The Marinids in particular, during their quarter-century-long reign over the city, en-
dowed Tlemcen with several monuments [12]. They are the Sidi Boumediene com-
pound, the Sidi Al-Halwi Mosque and the entire city of El-Mansourah. One key feature,
that established the ornamentation of this heritage, is the polychrome decoration with
inlaid glazed pottery called mosaic of faience (also referred to as zellij). The zellij is
complemented by stucco and wood decoration.


* Corresponding author: kheira.anissa@uaeu.ac.ae

                                                                                              27
                                                                                                                            Indeed, in architecture, everyone remarks on the colorful aspect of Islamic art. Blair
                                                                                                                         and Bloom [13] state that the use of color deliberately destabilizes a static geometrical
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         design by introducing a new dynamic in architecture, while Renan [11] compared the
                                                                                                                         wall decorations to colorful vertical carpets (Figure 1). Islamic religious buildings are
                                                                                                                         characteristically devoid of furniture. Ultimately, their surface treatment and the impor-
                                                                                                                         tance given to the choice of material coatings (ceramic for example) becomes of prime
                                                                                                                         importance.




                                                                                                                         Figure 1. Wall decoration with faience mosaics inside the Madrasa of Sidi Boumediene, Tlemcen,
                                                                                                                         Algeria. Source: Authors.

                                                                                                                             The colors enhance the character of the building, contributing to its image and its
                                                                                                                         spatial ambience, allowing appropriation of the space and modifying the atmosphere of
                                                                                                                         the place. According to Léger [14], color can totally change the atmosphere of a place
                                                                                                                         by creating a new space. The simple act of coloring a wall has the power to adorn it,
                                                                                                                         make it stand back, advance, or even destroy it.
                                                                                                                             The mural decorations in polychrome ceramics, moreover, provide a high aesthetic
                                                                                                                         quality to architectural monuments. Several specialists of Muslim Art consider these
                                                                                                                         mural decorations as full-ledged works of art [10, 15-17].
                                                                                                                             Colored decorative motifs allow an expression of patterns. It gives them a particular
                                                                                                                         appearance and depth, and therefore perfection [18]. Accordingly, the colors in this
                                                                                                                         Marinid ornamentation enhance the building character, contributing to its image and its
                                                                                                                         spatial ambience. On walls, the play of geometry combined with colors makes these
                                                                                                                         panels a work of abstract art, as Islamic art is devoid of igurative forms. According
                                                                                                                         to Barnet’s guide [1λ], non-objective art, unlike igurative art, depends on representa-
                                                                                                                         tive forms. It relies entirely on the emotional signiicance of color, form, texture, size
                                                                                                                         and spatial relationships.
                                                                                                                             In this regard, the polychromatic compositions of the ceramic mural decorations in
                                                                                                                         the Marinid Sidi Boumediene εosque and their resulting ambience, offer a fertile ield
                                                                                                                         of investigation, which has yet to reveal all its intrinsic spatial and aesthetical value.




                                                                                                                    28
   2. Objective of study and research methodology

    The aim of this study is therefore to investigate the unexplored role of color ce-
ramics in one work of representative architectural heritage belonging to the Marinid
dynasty; Sidi Boumediene εosque in Tlemcen, Algeria. The study has two speciic
objectivesν irst to inventory and document the colors of the mosaic of faïence panels
and analyze it as an artwork and secondly, to analyze the composition of the ceramics’
color and their resulting ambience.
    The irst objective, beyond the inventory of the colors used, consists of an artistic
analysis of the mosaic of faience panels and loors, considered as works of art by sev-
eral specialists of Muslim Art [10, 15-17]. The approach is based on the aesthetic and
artistic study of an artwork, as developed in Barnet’s guide [19]. The Barnet analysis
consists irstly, in placing the work studied in its historical and cultural contextν when,
where and why was the work made? By whom and for whom? The analysis also in-
volves examining the material, its limitations, the description and comparison of the
colors employed in each polychrome component.
    The second objective aims to analyze color composition and its resulting ambience.
This focuses on the effects of colors when juxtaposed, as their appearance depends on
how they are placed in the composition alongside other colors. The effect the arrange-
ment of these colors has on the ambiance created in the space is also addressed. For
this purpose, the analysis relies on a combination of approaches including the color
analysis from Barnet’s guide [19]; the laws of color contrast established by Itten [20];
and Goethe’s treatise of colors [21]. The color analysis in Barnet’s guide deines the
artistic color concept through Van Gogh’s study of his own artwork as the “marriage of
complementary colors, their mixture and their oppositions, the mysterious vibrations of
tones in each other’s proximity, to express the thought behind a brow, by the radiance
of a bright tone against a dark ground” [19]. The laws of color contrast (established by
Itten) analyze the three dimensions of color: the tint (color), the value (brightness), and




                                                                                                      CONSERVATION SCIENCE IN CULTURAL HERITAGE
the saturation level (purity or vividness of the color) [22, 23], and attempt to bring out the
relationship between these dimensions using color contrasts based on Itten’s work [20].
Goethe’s treatise of colors [21] develops1 the effects of colors, such as in distant-close,
warm-cold, by analogy with natural phenomena and the environment (sky, sun, ire etc.).
    The integrity of the information and the authenticity of the colors explored hereby,
are based on three sets of information. First, travelers’ tales were considered, such
as those by al-Hasan ibn Muhammad al-Wazzan al-Fasi, better known as Leo Afri-
canus2 [5, 24]. Second, surveys and construction drawings dating from the colonial
period were investigated. The monuments of Tlemcen and their surroundings were
irst identiied and drawn by military engineers and scientiic explorers. Starting from
1872, surveys were undertaken by Edmond Duthoit and Edouard Danjoy, followed by
the then-formed Service of Historical εonuments [4]. Finally, ield investigations were
carried out, using in-situ observations and photographic surveys.


   3. The polychrome ceramics in the Sidi Boumediene Mosque

   3.1. Sidi Boumediene Mosque; case study

  The relatively well-preserved architectural ensemble of Sidi Boumediene Mosque,
where polychrome ceramics were extensively used, was selected for this speciic

                                                                                                 29
                                                                                                                         study. An additional reason for this selection resides in the spiritual value bestowed
                                                                                                                         upon this building by worshipers and visitors alike.
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                            The Sidi Boumediene Mosque compound, located in the neighborhood of El Eub-
                                                                                                                         bad within the city of Tlemcen, was built in honor of Abu Choaïb Madyane (Boume-
                                                                                                                         diene) El Andaloussi. Boumediene was a teacher, writer, poet and an eminent refer-
                                                                                                                         ence of Suism in Algeria and the εaghreb. The architectural ensemble includes the
                                                                                                                         Sidi Boumediene Mosque, built in 1339 by the Marinid Sultan, Abu Hassan Ali. It also
                                                                                                                         includes the tomb of Sidi Boumediene himself, a Madrasa (religious school) built in
                                                                                                                         1347, and a small palace [7].
                                                                                                                            Sidi Boumediene Mosque stands out as a landmark and an attraction in the city of
                                                                                                                         Tlemcen. It is the lavish ornamentation, composed mainly of lat ceramic decorations
                                                                                                                         that make this building stand out as a remarkable heritage legacy [11]. The mosaic
                                                                                                                         of faience, in general, covers the base of the walls, the loors of the courtyards, the
                                                                                                                         porches and doorframes, as well as the upper part of the minarets. The artistic use of
                                                                                                                         color is superimposed on the ceramic tile work with geometric and loral arabesque
                                                                                                                         forms. Color creates speciic ambiences while highlighting architectural components,
                                                                                                                         exposing spatial richness and a distinctive prowess in its construction [24].
                                                                                                                            The visual attractiveness of the colored ceramics, the geometry of the patterns, and
                                                                                                                         the fractals in this important heritage have been broadly recognized in Sidi Boumedi-
                                                                                                                         ene Mosque’s architectural heritage. However, little has been done in terms of studying
                                                                                                                         the design and arrangement of the colors and their resulting ambience. This shortcom-
                                                                                                                         ing reinforces the main objective of this research, which is to explore the polychromy.

                                                                                                                            3.2. Color and materials in the ceramics of Sidi Boumediene Mosque

                                                                                                                             In Sidi Boumediene Mosque, the dominant pigments used, as described and clas-
                                                                                                                         siied by εarçais [5], are as followsμ
                                                                                                                             – White: half-matt, slightly greenish, very small cracks.
                                                                                                                             – Manganese brown: generally used very thickly, so as to form an almost black
                                                                                                                                tone.
                                                                                                                             – Yellow: an iron yellow, rather impure and produces a spotted yellow.
                                                                                                                             – Copper green: has an intrinsic value and a very variable tone. In the same con-
                                                                                                                                text, it can appear as very dark and very deep, or very clear, leaning towards
                                                                                                                                celadon or turquoise colors.
                                                                                                                             – Cobalt blue: quite rare. It does not seem to have been used in Tlemcen before
                                                                                                                                the second half of the sixteenth century; it is clear and almost pure.
                                                                                                                             The mosaics of faience are the heirs to the Byzantine mosaics, which were made of
                                                                                                                         colored glass paste and smalts. The Marinid mosaics of faience are made from multi-
                                                                                                                         colored tiles on stanniferous enamel. They form an assembly of varnished pieces with
                                                                                                                         different tones, cut according to a template and recessed into each other.

                                                                                                                            3.3. Description of the polychromatic elements of Sidi Boumediene Mosque

                                                                                                                            The chromatic analysis of the colored component elements of Sidi Boumediene
                                                                                                                         Mosque follows the visual encounter that a visitor may have in gradually discovering
                                                                                                                         the site. In exploring the site, viewing both at a distance and close-up, induces different
                                                                                                                         perceptual experiences. Hence, the mosque has been sequentially explored, starting
                                                                                                                         from external elements such as the porch and its details, to the stairs leading to the


                                                                                                                    30
entrance. Once inside the compound, the focus is then centered on the courtyard and
its colored paving. The minaret, visible from all perspectives, is addressed as a sepa-
rate component.
    1) The monumental entrance to the mosque consists of a porch adorned by a sev-
en-meter high horseshoe arch that encloses it. Eleven steps covered with colorful
mosaics, ultimately provide the arcade entrance with a majestic base (Figure 2).
    On the front porch, a triple festoon of brick, enameled with a green netting pattern,
divides the frame into two parts. The irst is the keystone, formed by a large circular
border around the hanger. The second is formed by two spandrels. The inishes of this
framework, the imposts that support it and the spandrels are in the form of arabesques.
They are in loral decor with interlacing double palms, regularly repeated in mosaic
tiles using four tones: white, brown, green and yellow iron. This ensemble is framed by
a green-toned ceramic net (Figure 3).




                                                                                                     CONSERVATION SCIENCE IN CULTURAL HERITAGE

Figure 2. Monumental access porch of Sidi     Figure 3. The front porch with a triple festoon
Boumediene Mosque. Source: Authors.           of bricks inlaid with an enameled green netting
                                              pattern. Source: Authors.

    The frieze that crowns the portal is decorated with inlaid bricks of brown enamel
plates and green bands, above ive radiating rosettes around eight-sided stars (Figure
4). The intrados of the arch carries regular geometric white, yellow and brown ocher
coatings. An epigraphic band, in black on a white background, announces the porch.
It is dedicated to Sultan Abu al-Hassan and surmounts the loral decoration (Figure 4).
In most cases, the jafr or “science of letters” is a poem devoted to the glory of God. In
decorative Muslim art, it is common to incorporate Qur’anic verses, or a Hadith of the
Prophet, or simply a poem. The subtle ornamentation of the porch marks the threshold
that gives access to an introvert interior.



                                                                                                31
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         a                                                b
                                                                                                                         Figure 4. Distant view (a) and close-up view (b) of the epigraphic inscription detail in cursive
                                                                                                                         composed of arabesques. Source: Authors.



                                                                                                                            2) The square courtyard of the mosque, delimited by the arch of the prayer hall in
                                                                                                                         front of the main entrance, has an onyx basin for ablutions at its center (Figure 5). This
                                                                                                                         courtyard is covered with simpler mosaics than the more ornate porch.




                                                                                                                         Figure 5. The courtyard of Sidi Boumediene Mosque, with polychrome mosaic of faience. Source:
                                                                                                                         Authors.

                                                                                                                           3) Similar to the porch and the doorframe, the minaret located at the northwest cor-
                                                                                                                         ner of the mosque, is richly decorated with polychrome mosaic (Figure 6).




                                                                                                                    32
a                                                 b
Figure 6. The top part of the minaret of the mosque with a geometric and polychrome decor of
rosettes. Source: Figure (a): water color by Duthoit 1872 (authorized by © Ministère de la culture
(France), the εédiathèque de l’architecture et du patrimoine (Paris)); Figure (b): Authors.



    4. Chromatic composition of the architectural elements and the resulting am-
    bience




                                                                                                          CONSERVATION SCIENCE IN CULTURAL HERITAGE
   The tonal range of the ceramics that cover the architectonic elements of the mosque
is not very varied. The resulting vivid effect lies in the purity of each color and its
value compared to the other tones. The color analysis in terms of hue, saturation and
brightness that are carried through, identify the colored features used in the different
architectural elements.




Figure 7. Chromatic survey of faience mosaics used in the architectural elements.


                                                                                                     33
                                                                                                                            The shape and size of the colored spots in Figure 7 differ from one element to an-
                                                                                                                         other. The purest hues are located on the outer fringe of the circle and become less
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         pure, or less saturated, as they move further away from the circumference. Hence, the
                                                                                                                         green and the ocher-yellow are both pure colors and similar in brightness. When the
                                                                                                                         colors used are compared with each other, they form different contrasts.
                                                                                                                            As Indicated in Table 1, the encounter with colored sets can be appreciated in two
                                                                                                                         ways. From a distance one can contemplate the colorful ornamentation and obtain a
                                                                                                                         general overview with an optical mixture of colors, resulting in a speciic atmosphere
                                                                                                                         (Figure 8). Up close, the intricate designs and the variety of their colors can be appreci-
                                                                                                                         ated differently [26].




                                                                                                                         Figure 8. The décor in rich polychrome ceramic of the porch contrasts with the surrounding white
                                                                                                                         and sober walls. Source: Authors.

                                                                                                                            Both inside and outside the building, the choice of decorated elements appears an
                                                                                                                         intentional and deliberate act. Generally, they are representative and allegorical ele-
                                                                                                                         ments with complex scenery and can be contemplated from afar. The colorful appear-
                                                                                                                         ance attracts the attention because of the foreshortening effect of the colors. These
                                                                                                                         various elements modulate the perception of the polychrome mosaic composition, ac-
                                                                                                                         cording to an optical forward or withdrawal movement.

                                                                                                                            4.1 The porch and its components

                                                                                                                            The access to the mosque is the subject of a particular staging and is enhanced by
                                                                                                                         the magical work of colors (Figure 2, Figure 3). This richly colored frontage serves as
                                                                                                                         an announcement and a preamble to the monument. Its colored appearance contrasts
                                                                                                                         with the white background of the adjacent walls (Figure 8, Figure 10) which captures
                                                                                                                         and relects the light.


                                                                                                                    34
    Color highlights the architectural objects and creates animation, particularly in an
achromatic environment [27]. The resulting impression from the color combinations
can be best evaluated through an analysis of the different types of chromatic contrasts.
In this regard, the warm/cold contrast above a neutral background (Figure 5, Figure 9)
causes a perceptual effect of relief, allowing only an approximation of the object, and
thus suggesting a strong invitation to ind out more about the object itself. Furthermore,
the colored spots of the porch (green, ocher-yellow, black and white), placed side-by-
side, provide a pointillism effect.
    This optical phenomenon is not that of camaieu, where colors are closer in their
tonalities and fused together by the brain. From a distance, the colored spots with
different tones create an optical mixture in the observer’s eye: the human eye tends
to accentuate the differences by eliminating similarities [27]. This color combination
reinforces the repeated colors and their after-images. It synthesizes an overall picture
of warm hues [28]. Noted color theorist, Josef Albers [29], explains that color is the
most relative element in art and astutely observes how some colors appear to shift in
appearance when placed next to others.
    Likewise, the clear/obscure contrast and the contrast in brightness provide the walls
with lickering effects. For instance, the walls are enhanced by the ocher-yellow spots
which gleam in the sun and thus highlight the brick color. This interplay of colors con-
fers the polychrome adornment with qualities of brilliance, warmth and colorfulness.
Similarly, the irregularity of the small mosaic pieces catches the light. This creates a
play of shadow and light, making the walls scintillate and vibrate and suggesting a light
volume.
    The general view helps see how the details it into the entire monumental gate.
These architectural details are described and further analyzed below.

   4.1.1. The calligraphy above the porch decoration




                                                                                                   CONSERVATION SCIENCE IN CULTURAL HERITAGE
   The viewing distance transforms the perception one has of the building. From the
overall vision and physical masses, the visitor moves to the graphic universe of the or-
namentation. The cursive calligraphy is one element in the composition of intertwined
leaves and stems (tawriq) in a set of curves and counter curves. This iligree foliage
decor is made up of a succession of spirals inscribed in tangent circles (Figure 4). The
colored (green and ocher) loral patterns mingle, intertwine and contrast with the black
calligraphy. According to Paccard [18], in a similar way to colors, loral forms create
either continuity and complement each other, or they create a contrast, which makes
them stand out. This visual phenomenon suggests ingenuity and synchronization.
   Similarly, the colors used are very dark brown, white, green and ocher-yellow. On
the epigraphic frieze, the dark tone is reserved for the calligraphy. The latter emerges
in contrast with the clear colors of the tawriq patterns (loral decoration). The black and
white contrast (clear/obscure contrast) highlights the calligraphy. It also highlights the
green color of the foliage, which becomes a key element in the composition. This entire
setup is composed of arabesques on a white background.
   In this loral composition, the color contrast is greatly pronounced. It creates a raised
pattern effect. The calligraphy and the loral decor, in dark brown, seem to stand out
from the white background (contrast between advancing and receding colors). “The
clear/obscure is needed to develop not only a sense of proportions, but also a connec-
tion between the dark form, thought of as positive, and the white as negative” [20, p


                                                                                              35
                                                                                                                         40]. For painters, white and black are the strongest means of expression for light and
                                                                                                                         darkness. From the point of view of their effects, white and black relect the ultimate
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         opposition or contrast [20].

                                                                                                                            4.1.2. Polychrome decoration of the arch: keystone, impost and spandrels

                                                                                                                            In the lower arrangement that adorns the keystone and the impost of the arch, the
                                                                                                                         colors of the leaves are set in yellow, green, black and white. The color contrast (hue,
                                                                                                                         temperature and brightness) is visibly accentuated. The dark brown loral decor stands
                                                                                                                         out from its white background. It creates a counterbalance effect (Figure 9).




                                                                                                                             a                                                 b
                                                                                                                         Figure 9. Distant view: Figure (a), and close-up view: Figure (b) of the loral decoration: mosaic tile
                                                                                                                         work with a combination of leaves and stems interwoven into a set of curves and counter-curves.
                                                                                                                         Source: Authors.

                                                                                                                             The black on white makes the shape smaller, while the tone-on-tone of the color
                                                                                                                         with its background makes it appear ininite [27]. In addition, color is never perceived
                                                                                                                         alone, but always according to its setting. “A color that appears dark in one palette,
                                                                                                                         for instance, may be judged lighter in another context, while a hue that appears bright
                                                                                                                         in one palette, may appear less saturated among other colors” [30, p. 7]. The black
                                                                                                                         graphic design of leaves is accentuated, because clear colors appear brighter on a
                                                                                                                         dark background and darker on a lighter one. The green and ocher-yellow tones, in
                                                                                                                         proximity to the black leaves (thus creating a dark background), appear larger and
                                                                                                                         radiate outwards. However, they appear duller close to the white leaves, therefore
                                                                                                                         creating a compensation effect.
                                                                                                                             The intrados and spandrels are an ensemble of stylized motives. They are under-
                                                                                                                         lined by a series of green strips, within which geometric and loral motives are alter-
                                                                                                                         nated. These green strips accentuate the arch and envelop the scalloped brick, as
                                                                                                                         well as other details of the porch. They also strengthen the edges of the composition.
                                                                                                                         The principle of the frame is derived from Byzantine design. However, for Muslim art-
                                                                                                                         ists, the frame could cut an endless network of patterns. Paccard [18] designates this


                                                                                                                    36
a                                                  b



framework, which cuts the patterns in random places, as a window that opens onto an
unlimited world.

    4.1.3. Polychromy of the stave of the bow or intrados

    Within an architectural context, color changes its appearance. It becomes rather
free lowing and mobile, contrary to its stable and static nature [27]. In this context,
geometric motifs are combined with vegetal patterns. Indeed, on the surface of the
intrados (Figure 10), there is an oblique weft. The latter creates brown diamonds of
identical shape. The resulting geometric characteristic of the diamonds, and depend-
ing on their direction, appears to make them interlock with each other.




                                                                                                            CONSERVATION SCIENCE IN CULTURAL HERITAGE
    a                                                b
Figure 10. Underside geometric design of the arch (a), and as documented in 1872 (b). Source:
Figure (a): Authors, Figure (b): water color by Duthoi 1872 (authorized by © Ministère de la culture
(France), the Médiathèque de l’architecture et du patrimoine, Paris).

    These black surfaces are surrounded by ocher-yellow stripes. Their arrangement
is based on a clear/obscure contrast. This results in a play of light, shadow and relief.
According to Itten [20], light colors tend to recoil, while dark colors move forward. At
the same time, this combination of tones designates a contrast of quality. The latter is
the contrast between the bright yellow ocher and the dull brown, because of its mixture
with the black. This further accentuates the brightness of the ocher-yellow and pro-
vides it with the brilliant effect of the gold color. The Marinids yearned for the golden
color, as it inluenced happiness and continuity [31]. This panoply of colors enhances
and enriches the white plaster coating. It generates a graphic of the grids, with a play
of light and shadows that animate and enliven the arc.
    On the intrados, the combined diamond-patterns are geometrized vine leaves. They
are called “shoulder and step”, (ktaf ou darj) [18]. The shoulder is the curve and the
step is the small right angle that succeeds it (Figure 10). The intersection of broken
lines determines a spearhead shape. The motifs are highlighted by a white outline,
emphasizing the design of geometric leaves. In the adornment of the intrados, the ktaf
and darj grid is essential. It serves as a structure for the loral decoration. The strip


                                                                                                       37
                                                                                                                         frieze on the leaves acts as a counterpart. It is accentuated by the use of contrasting
                                                                                                                         colors. It creates an effect referred to as a ‘counterbalance of values’ [16], in the same
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         ceramic mosaic panel.
                                                                                                                             The yellow palm leaf, placed near the brown one (almost black), is added to the
                                                                                                                         loral composition of the intrados. It afirms the clear/obscure contrast in addition to the
                                                                                                                         quality contrast. It is the opposition between the saturated bright yellow ocher and the
                                                                                                                         dark brown, considered as a dull color [20]. In this case, the yellow color illuminates
                                                                                                                         the chromatic ensemble. It replaces gold, gild and spark. It represents the energy and
                                                                                                                         the wealth of the Marinid dynasty. In this case study, yellow is similar to the color of the
                                                                                                                         brick and consequently creates harmony.
                                                                                                                             In this composition, the complementarity of shapes is associated with an opposi-
                                                                                                                         tion between two values or two colors; black and white (the white on black highlights
                                                                                                                         the lines of the pattern), raw brick and glazed brick. The function of this opposition is
                                                                                                                         to disrupt the relationship between form and background. This combination of shapes
                                                                                                                         and colors allows the transformation of the architectural context into a lively and sig-
                                                                                                                         niicant space.

                                                                                                                            4.2. The stairs

                                                                                                                            A staircase, allowing access to the mosque, leads to the monumental door. Eleven
                                                                                                                         steps provide this arcade with a majestic base (Figure 2). The stair risers are decorat-
                                                                                                                         ed with a mosaic of small multicolored diamonds. The patterns are totally different from
                                                                                                                         the rest of the porch decor, but their tones are identical. This chromatic unit enables a
                                                                                                                         visually pleasing continuity with the architectural elements [18]. The colored fragments
                                                                                                                         in diamond shapes are smaller than those that adorn the courtyard of the mosque.
                                                                                                                         Framed by a green ceramic surround, they are the unique decoration of the staircase.
                                                                                                                            The green, black (dark brown) and ocher-yellow colors enhance and contrast with
                                                                                                                         the white marble steps. The latter illuminates the space through its high level of light
                                                                                                                         relectance. Similarly, the polychrome decoration contrasts with the neutral tones of
                                                                                                                         the sidewalls that lank the stairs. These colored arrangements break the monotony of
                                                                                                                         the long white walls.

                                                                                                                            4.3. The courtyard paving of the Mosque

                                                                                                                             The subtle ornamentation of the porch and the stair risers mark the threshold to an
                                                                                                                         inward focused interior space: the square courtyard of the mosque. The decorated
                                                                                                                         facades are introverted, inwardly facing. They surround the faithful on all sides, to form
                                                                                                                         a “box of dreams”, in which everything is wealth and poetry [16].
                                                                                                                             The courtyard is covered with mosaics on a square grid (Figure 5). Much less com-
                                                                                                                         plex than the ornate porch, the loor inserts are composed of small diamonds of vari-
                                                                                                                         ous colors, organized in 45° diagonals. They are multiplied to ininity, interrupted only
                                                                                                                         by the walls. Tiles are assembled side by side and arranged diagonally in rows of
                                                                                                                         diamonds with the same nuance. They are also set in bands, through an arrangement
                                                                                                                         of tones: manganese brown, copper green, iron yellow, and white. The diagonal bands,
                                                                                                                         joined to each other, form a checkerboard design, thus highlighting a grid loor plan.
                                                                                                                         The square is a basic geometrical element that can be multiplied ininitely and forms
                                                                                                                         a grid. The extension of motifs is interrupted by frames or friezes, beyond which they
                                                                                                                         appear to pursue their invisible repetitions.


                                                                                                                    38
    It is important to note how colors are the common denominator to both surfaces;
those of the ceramics covering the loor of the patio and those of the porch. This pro-
duces a harmonious continuity. In this assortment of grids and shapes, there is an aes-
thetic unity and color is one of the items that ensures this unity. “Color palettes offer a
way to unify the interior with the exterior and can visually connect one interior space to
another.” [30, p.7]. The formal design of the pavement, where geometry is associated
with color, plays a contrasting role and highlights the fountain in the middle of the patio.
    As discussed earlier, color combinations between light (ocher-yellow, green and
white) and dark (black) tones create a weaving effect. The strips of dark diamonds print
their trail on a white background. Each tone acquires a value as opposed to another
tone. There is a whole range of variations on the weaving principle, with interesting
similarities found in the textile arts [16].
    In addition, the accumulation of patterns and the incessant repetition of the same
form cause an optical effect of scintillating rotations, which make the ocher-yellow
shine. The decor encases the entire loor surface, like an enveloping membrane. The
relation between colors provides an impression of movement. The afinity between
colored surfaces and the contact between tones makes the color a plastic work of art.
    At the pavement level, color creates a uniform frame effect, a lattice that enhances the
geometry. The combinational logic of colors inside this frame creates visual effects, ac-
centuating the perspective within this architectural space. Contrasting colors (black, white
and yellow) accentuate the design of both frames and patterns. The results are optical phe-
nomena of vibration, because the eye is often undecided between clear and dark forms.
    The frame is a linear geometric distribution of these compositions, creating a net-
work combination. For the viewer, the visual result is a space in dynamic motion. The
latter is enlightened by white, illuminated by yellow and punctuated by green. The
black serves to emphasize and express these nuances. Yellow is considered to be
the warmest color. Under the sun, it shines and relects daylight. It procures a bright
atmosphere, a warm ambience, and engenders a sense of belonging to the space [21].




                                                                                                    CONSERVATION SCIENCE IN CULTURAL HERITAGE
Yellow is a color that gives a feeling of warmth and well-being; it is an active color and
its role is to illuminate this space [21].
    The colored loor is open to the sky. It decorates the sparsely furnished space and is
darker than its monochromatic surroundings. Principally, it highlights the central patio
space, accentuates its stability and provides a recognizable landmark for visitors. The
color difference between the ground and its lanking sides allows the contours of the
architectural elements, such as the embrasures and pillars, to be traced.

   4.4. The Minaret

    Well above the architectural ensemble of Sidi Boumediene rises the minaret at its
northwest corner (Figure 6). The main vocation of this pinnacle is to provide the muez-
zin with a higher point for the ive daily prayer calls. It also has a symbolic and political
role as it is seen as an indicator set up to show the way to the faithful [32]. Hence,
it is visible within and beyond the city. The svelte form of this architectural element
dominates the monument. It is considered to be one of the most attractive still-standing
specimens of its kind [5]. Its elegance resides in the balance of its proportions and the
variety of its intermediate sections. Finally, in order to be perceived from afar, a richly
encrusted multicolored mosaic decorates its top. The minaret appears to invite the
viewer to come closer.


                                                                                               39
                                                                                                                             The minaret is built and decorated in adorned and scalloped brick, where light
                                                                                                                         and shade play a distinct role. The tile mosaic that adorns this pinnacle is com-
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         posed on each side by a frieze of four rosettes of elaborate geometrical construc-
                                                                                                                         tion. Two half-rosettes appear on the other faces (Figure 6). A tangle of white
                                                                                                                         threads limits the surfaces. The black is enclosed within the yellow. It forms a
                                                                                                                         star with twenty-four points surrounded by broken lines. The green ceramic band
                                                                                                                         frames the ensemble.
                                                                                                                             The polychromic rosettes of the minaret create a double contrast. First, the clear-
                                                                                                                         obscure one and second, the contrast of value or quality “bright, dull” [20, p. 37]. The
                                                                                                                         latter emphasizes the spark of the yellow color and forms a bright spot in the “dark and
                                                                                                                         dull” [20, p. 37] surface that surrounds it. In the unfolding of the friezes, the whole is
                                                                                                                         punctuated by yellow dots which add luminous touches throughout.
                                                                                                                             A row of crenellations crowns the main body of the tower. They carry a mosaic
                                                                                                                         decoration that unfortunately has been badly impacted over time. This adornment is
                                                                                                                         composed of white star-shaped polygons on a black background. The different colors
                                                                                                                         assigned to the different forms, allow them to be distinguished from each other. In-
                                                                                                                         terpretation of the forms can also be accentuated by alternating clear shapes with
                                                                                                                         dark ones [16]. The pattern stands out as a white active form on a dark background,
                                                                                                                         allowing it to highlight the geometrical forms. Bands of green tones underline the ce-
                                                                                                                         ramic panel. With the clear-obscure contrast, the entire surface takes on a plastically
                                                                                                                         animated character. The pattern is highlighted and stands out as a dark active form on
                                                                                                                         a white background.
                                                                                                                             Color contrasts reinforce the principle of counterbalance. The latter resides in the
                                                                                                                         ambiguity of forms and colors: black and white, full and empty, presence and absence.
                                                                                                                         Indeed, the reading of some igures varies, depending on the eye, which eliminates
                                                                                                                         either the clear or dark shapes. This alternate reading gives rhythm to the composition
                                                                                                                         and fascinates the viewer [33].

                                                                                                                         Table 1. Visual and spatial effects of the polychrome patterns based on color contrast as perceived
                                                                                                                         from a distance and close up.
                                                                                                                                                                   View from a distance




                                                                                                                                    Hue contrast                   Clear/obscure contrast                 Temperature contrast
                                                                                                                          The colored spots, placed side-by-    Color combinations between light             Foreshortening effects
                                                                                                                           side, provide a multicolored and       tones (ocher-yellow, green and       and attractiveness. The optical
                                                                                                                                     pointillist effect.         white), and dark (black) create a    mixture draws its liveliness from
                                                                                                                             The optical mixture reinforces               weaving effect.              the temperature change in the
                                                                                                                             the repeated colors and their         The color combination of the       green (cool color) and the ocher
                                                                                                                          afterimages, in order to synthesize   checkerboard paving emphasizes                yellow (warm color).
                                                                                                                           an overall picture of warm hues.      the perspective. It is highlighted     - Illusion of relief of the ocher
                                                                                                                           The contrast of hues achieves a            by the monochromatic             yellow and depth of the green.
                                                                                                                           colorful patio paving that creates     environment (white color). The           - Appeal and attraction of
                                                                                                                               movement and animation.              colored loor decorates the           the object highlighted by the
                                                                                                                                                                     sparsely furnished space.        brightness of the ocher yellow, a
                                                                                                                                                                                                                shimmering color.




                                                                                                                    40
                    Close-up view - colors offer better perception of details




         Quality contrast                  Temperature contrast                 Clear/obscure contrast
   The black on white makes the           The black graphic leaf design           The calligraphy appears
   shape smaller, while the tone-         is accentuated because clear            to emerge from its white
     on-tone of the color with its      colors appear brighter on a dark                background.
    background makes it appear             background and darker on a            Visual balance: the white
                ininite.               lighter one. The light tones; white    background weakens the clear
      The black as a dull color         and ocher-yellow, in proximity to     colors and makes them appear
 accentuates the brightness of the      the black leaves (thus creating a        dull; while the black color
 ocher-yellow and provides it with a    dark background), appear larger      highlights the colours and makes
       brilliant golden effect.               and radiate outwards.             them appear brighter. This
  The yellow color illuminates the                                            contrast creates a play of light
  chromatic ensemble. It replaces                                            and shadow and a play of relief.
  the gold, the gild and the spark.                                            Light colors tend to withdraw,
                                                                             while the dark colors move to the
                                                                                         foreground.



   5. Conclusion

    The mosaics of faience played an important role in the decorations of the medi-
eval Islamic architecture of Tlemcen. Its proven resistance to the elements made it a
preeminent coating for exteriors. Permanent colors are ixed to the portals, minarets,




                                                                                                                      CONSERVATION SCIENCE IN CULTURAL HERITAGE
and courtyards of the mosques and major public buildings. Sidi Boumediene Mosque
is a representative heritage of that period and its color ceramics have been the focus
of this paper.
    Colors are used in isolated fragments or small groups and encrusted in a brick ap-
paratus, as an exterior inish. The tones are bright spots in the matt or dark surfaces
that surround them. They are assembled in strips of a single tone highlighting architec-
tural lines and facilitating formal reading. They are also combined into complete panels
composed of interlacing geometric and loral designs mostly on a white background.
Color gradients, that suggest the volumes, have been replaced by a play of contrasting
oppositions, relecting a more graphic understanding of the form.
    The visual impact of these decorated spaces is intimately related to the outstand-
ing adorning which covers them. Indeed, the polychrome ceramics transform the look
of the architectural space. It has a decisive inluence on the appearance of a building
and the atmosphere that emerges, giving it an identity and a sense to its geometric
composition.
    The ceramics adorn the lat surfaces, with colors in chiaroscuro, producing con-
trasts in hue, quality and temperature. The latter provide the impression of relief, form
and background effect, together with an impression of light and darkness, of optical
mixture and lickering effects. Although small in number, the four tints provide a surpris-
ing palette of high-quality decorations that are rich and varied.


                                                                                                                 41
                                                                                                                            The image of this architecture, its aesthetics and polychromy is a visual memory
                                                                                                                         that enhances the built heritage. Documenting it enables the conservation of the chro-
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         matic authenticity of this architectural heritage. It also provides the necessary data for
                                                                                                                         prospective conservation, as well as forming a basis for its integration as a potential
                                                                                                                         expression of contemporary cultural identity.


                                                                                                                               Notes
                                                                                                                         1
                                                                                                                          Speciically in relation to his last chapter.
                                                                                                                         2
                                                                                                                          Leo Africanus was born in Granada around 1486-1488 and died in Tunis around 1535. He was
                                                                                                                         a diplomat and explorer of North Africa, during the ifteenth and sixteenth centuries.



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                                                                                                 CONSERVATION SCIENCE IN CULTURAL HERITAGE
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  Biographical notes

   Meriem Benkhedda is an architect and PhD candidate and is currently teaching
plastic and graphic art in the Architectural Program at the University of Science and
Technology of Oran, Algeria. She specializes in color theory and application in the built
environment in general with a focus on Islamic Architectural heritage in the Maghreb.

   Kheira Tabet Aoul is a Professor of Architecture at the United Arab Emirates Uni-
versity, UAE. She draws from over 25 years of international academic and professional
experience in Algeria, the USA and Middle East. Her research focuses on green build-
ings, sustainable heritage conservation and human factors in the built environment.




                                                                                            43
                                                                                                                            Summary
                                                                                                                            The study and research described in this paper aims to reveal the unexplored aes-
M. Benkhedda, K. Tabet Aoul - Polychrome ceramics, artistic diagnosis and resulting ambiences in a Marinid mosque




                                                                                                                         thetical role of colors used for the ceramics in a mosque from the Marinid dynasty in
                                                                                                                         Tlemcen, Algeria. The methodological approach consists irstly, of a formal analysis of
                                                                                                                         the mosque’s artwork by describing its elements and composition and related princi-
                                                                                                                         ples. Secondly, the patterns and geometries are analyzed in-depth using artistic color
                                                                                                                         concepts and laws of color contrast. The analysis demonstrates that the contrasts
                                                                                                                         between bright, pure and dynamic colors provide luminosity, dynamism, rhythm, bright-
                                                                                                                         ness and an optical mix. The color contrasts are also found to provide visual illusions
                                                                                                                         of mass, volume or movement, as well as depth and relief that ultimately result in
                                                                                                                         inluencing the overall ambience of the mosque. The study thus enables the chromatic
                                                                                                                         authenticity of this architectural heritage to be preserved by providing the necessary
                                                                                                                         data for potential conservation, as well as providing a basis for innovative principles in
                                                                                                                         expressing contemporary architecture.

                                                                                                                             Riassunto
                                                                                                                             La ricerca è rivolta alla conoscenza dei colori impiegati nelle ceramiche presenti
                                                                                                                         nella moschea della dinastia Marinid a Tlemcen, in Algeria. L’approccio metodologico
                                                                                                                         consiste, innanzitutto, nella trattazione degli aspetti artistici della moschea, descriv-
                                                                                                                         endo i principi ai quali essi si riferiscono. In secondo luogo, i modelli e le geometrie
                                                                                                                         dei colori vengono presi in esame dal punto di vista estetico e nel contrasto dei col-
                                                                                                                         ori. L’analisi dimostra che i contrasti tra colori luminosi, colori puri e dinamici fornis-
                                                                                                                         cono luminosità, dinamismo, ritmo. Tali contrasti danno luogo anche a illusioni visive
                                                                                                                         di massa, volume e movimento, nonché profonditàμ in ultima analisi essi inluiscono
                                                                                                                         particolarmente sull’ambiente della Moschea. D’altra parte, questa ricerca consente
                                                                                                                         di preservare l’autenticità cromatica di questo patrimonio architettonico fornendo i dati
                                                                                                                         necessari per la conservazione, nonché alcuni principi innovativi sull’architettura con-
                                                                                                                         temporanea.




                                                                                                                    44
