CERAMIC TILES

On the facades of common architecture in the historical centre of Porto

Master course in Methodologies of Intervention on the Architectural Patrimony

Faculty of Architecture, University of Porto

2006/2007.

Traditional constructive techniques and materials

Prof. dr José Aguiar

student: Ivana Korać

Traditional constructive materials and techniques Ivana Korać

MIPA - FAUP 2006/2007. 2

Index 1. Introduction 3 2. Historical frame 4 3. Techniques and patterns 7 4. Pathology and main anomalies of tiles 11 5. Techniques of conservation and restoration 13 6. Bibliography 15

Traditional constructive materials and techniques Ivana Korać

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1. Introduction

One of the most interesting phenomena of Portuguese architecture is façade covering with ceramic tiles. With the notion of the humid climate conditions in Portugal and the isolation characteristics of this material, the rational reasons for their use are obvious, but what is so impressive about this occurrence is the diversity of their design and their role of a background for some magnificent artistic expressions. Although it is not originally Portuguese invention, it is deeply integrated in its culture and represents one of the most impressive features of the Portuguese urban images. Different types of tiles, found on the facades of Portuguese civil architecture, glazed monochrome, colourfully patterned or even relieved, give to each one structural piece a carefully sampled and architecturally integrated surface finishing and at the same time act as a recognizable element that gives one building its own identity. Aligned one next to another, creating a colourful street fronts, or seen as a dynamic mosaic that forms the image of the historical centres in whole, the buildings covered with ceramic tiles attribute to the notion of Portuguese design trends and ceramic tile technical progress throughout the centuries. Even though most interesting examples of the ceramic tile art are the ones that decorate the walls of many churches, palaces or some other public buildings, picturesquely describing different historical moments or carrying religious or ethnic motifs, in this work more attention will be given to the ceramic tiles façade coverings of the plain civil architecture, as they are, in a sense of protection, being more neglected than the other monumental examples.

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2. Historical frame 2.1 15th to 19th century The first known examples of the ceramic tiles wall-covering in Portugal were Hispano-Mourish tiles, imported from Seville in around 1503. The Arab presence in the Iberian Peninsula left some lasting cultural consequences and one of them is the practice of tile making. At that time Seville was the big centre of tile industry which used the ‘’cuarda seca’’ and ‘’cuenca’’ techniques until the mid 16th century, with the motifs that evolved from geometric Moorish lace-like and looping designs into European plant and animal themes which gradually progressed from the Gothic to the pure Renaissance style. Apart from the motifs themselves, Portugal retained a Moorish taste for excess in the practice of completely covering surfaces with decorations. In the 16th century, the development of the ceramic art in Italy led to the use of majolica technique – painting directly onto the tiles. In that way, the compositions were expanded including a variety of figurative themes, historical stories and decorations. Italian ceramists then moved to the Flanders region where they disseminated mannerist decorative motifs and the themes of antique classicism. After Portuguese orders have been placed in Flanders, some Flemish ceramists moved to Lisbon and initiated the tile production in Portugal from the second half of the 16th century onwards. Because of the high cost of large and unique compositions on the wall coverings, the repetitive patterns became more common and at the end of the 16th and the beginning of the 17th century chequered designs became very popular. They were composed of plain coloured tiles, alternated in the way that would create decorative patterns on the walls when combined. This time, because of the cost of the appliance on the wall, these types of tiles were substituted for the standard-pattern tiles, produced in large quantities and which were easy to apply. In the second quarter of the 18th century, an increase of the Portuguese tile manufacture happened partly due to many orders from Brazil. This period, called ‘’Great Production’’ overlapped the reign of King Dom João V and the execution of the largest cycles of historical panels ever made in Portugal. This kind of production led to the repetition of the same motifs like vases of flowers and the simplification of the painting of the scenes themselves, while the surrounding frames also took on a great scenographic importance.

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2.2 19th and 20th century The 19th century revealed new techniques to the factories, exited from the industrial revolution, and a consequent production of the series which favoured the return of the patterned tiles. In the second half of the 19th century, inside the eclectic self-tolerance of Romanism, a painted type of tiles, more related to the individual compositions appeared. Those are decorative panels of figurative and ornamental character, made for a specific façade, often linked to some new utilities – application on the commercial establishments. Some factories have specialized for this type of production, like Sacavém, Viúva Lamego, Campolide e Sant’Anna (in Lisbon), Carvalhinho (in Porto) and Fonte Nova and Aleluia (in Aveiro). The taste for the tiles at the facades of a civil architecture was developed in Portugal, from the middle 19th century, by the Portuguese emigrants who, after making a fortune in Brazil, had returned to the country. They had revealed the utilisation of the tiles as façade clothing following a current tradition in Brazil from the past century. The tiles were taken to these countries by the Portuguese, serving as ship balance ballast, which had affected the commercial trades during the 17th and 18th centuries. Parts of this ballast were decorative panels for churches and palaces and parts were just plain white tiles for common uses. Application of white tiles on the exteriors of churches and houses had generalized from the 18th century. In this way, they had preserved the constructions from the hot and humid climate that is characteristic in the tropical zones of Brazil. The façade clothing with ceramic tiles protects the houses from the erosion provoked by the strong rains and reduces the interior temperature. It is a material with the isolating characteristics, cheap, of great durability and easy to conserve. Functional use of the tiles is complemented by its decorative role as the animator of the façade surfaces, while giving simultaneously the colour and purity to the building. In Portugal, padding of blank spaces on the facades with ceramic tiles had first happened in the area of Porto and Gaia, the centre of the bourgeois development and the field of the attraction for the emigrants who came back to the region of their origins; after it had passed to the provinces of Minho and Douro and very quickly to the whole country, they ended by being totally accepted in the Portuguese society.

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Different artistic values of the tiles decoration, characteristic for the Romantic culture, have remained until the beginning of the 20th century, parallel to what had happened to the areas of paining and sculpture, where the aesthetic of Naturalism had started to dominate. Using traditional technique of the brush painting on the tined glass surfaces, some authors had freely recreated or imitated the styles from the past. Historic and nationalistic tile art, with folklore or religious character, emphasized determined themes, like the monuments, landscapes, ethnographic motives, scenes and typical figures of any region or some marked episodes from the Portuguese history. Lots of train stations and markets were decorated with the panels of this artistic tendency, like for an example the São Bento train station in Porto is.

Walls of the São Bento train station The 20’s and the 30’s of the 20th century were marked by the geometrical and more clear motives and forms, replying to the changes of taste that resulted from the Great War. Geometrical compositions of the Art Deco patterns presented a character more rational and clarified with the characteristic design. From the beginning of the 40’s, the architecture of the ‘’New Age’’ (implanted as a direct consequence of the Portuguese World Exposition in 1940) had eliminated the decorative use of the tiles in architecture. Considered to be the ‘’Minor art’’, the tiles were substituted with some new materials for the finishing, like the clothing in marble or glass and hydraulic mosaics. From that point, various artists had realised their work of recuperation and renovation of the tiles, with the aim of integrating this part of Portuguese tradition into the modern art.

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3. Techniques and patterns A tile is a ceramic piece of plain faience composed of one plate (generally square, but can be rectangular also), made of cooked clay and glazed on the illustrious side, which serves as a surface that supports the colour and design. A tile used as a covering material for the buildings exteriors is basically the tile with patterns of traditional wallpaper from the 17th century. Frequently it is a rectangular tile, monochrome and faceted. Façade tile covering is based on the regular repetition of one or more tiles in order to form patterns. One unique tile can content its own complete pattern, permitting itself an independent character in relation to the rest. But the major of patterns are composed from the modules of 4 equal elements, following the formula 2x2/1. Rarely the patterns are formed of 2 or more equal tiles. In most cases the tiles cover the whole surface, inserting itself clearly in the architectonic organisation of the façade. The colour and the design (that is better seen from the distance) enrich and characterize the building. The design can be done in a natural way which doesn’t affect the visual function of the façade, giving it just more or less intense pigmentation, a coloured mark visible from a far. But in other cases, diluting a design of a detail with a distance, the lines of the force stand on the surface. In that way, the rhythm of decorative motives annuls the static character of the facades, giving it its own dynamics by the lines of the perpendicular or diagonal tension. Also the reticles, resulting as an assembly of tiles, form one quadrille grid, dimensioning the surface. The expressiveness of some patterns can transform the own expression of the building – in order to contrary the verticality of construction, the pattern with the horizontal sense would be applied, and vice versa. The tiles with a pattern are most favourable for the production in the series, either half-industrial, by the processes of manual repetition (stamping or manual stamping and the high-relief) either industrialized (mechanically stamped and half-relief tiles).

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HALF-INDUSTRIALIZED – STAMPED TILES The factories that produced this type of tiles have adopted a standard format (13x13 or 14x14 cm). The paining was manually done – with a broad brush the paint would be put on the tile, over the pattern-cut wax paper which would leave a pattern -‘’stamp’’ on a tile already clothed in enamelled tin. Frequently one was able to see on such a tile the traces of a brush’s hairs as well as the light spreading of the pigment/tint near its limits, which would help to distinguish this process of decoration. During the second half of the 19th century the variety of ‘’commercialized’’ stamped tiles was great, although they were only a simple compositions in blue and white colour or with some polychromatic schemes. In the cases of monochrome decoration only one stamp was used; for the decoration with various colours, one stamp would correspond to only one colour. Some patterns had the manual finishing, like brush strokes, contours and other painting marks made with a fine brush, which appears usually at the older examples. Decorative motifs go from the geometrical compositions to the floral elements or the designs inspired by the antique patterns. On the 18th century designs the patterns are clearly influenced by the design that comes from abroad (from England, France and Netherlands), either directly by the cognition of the catalogues or the import of the matrixes, either indirectly by divulgation of the designs on the textiles or wallpapers of that time fashion. A copy of the foreign model contributed to the impoverishment of the Portuguese character of the ornamental motifs. One of the biggest factories that produced tiles in this époque was Fábrica das Devezas. The patterns of the factories from Porto are different from the patterns of the Lisbon factories, where the first give preponderance to the geometrical elements in more complex and refined way, with domination of dark colours like brown, violet, the colour of vine and black, while in Lisbon, the tiles were characterised by a simpler design, with vegetal or floral stylization or geometric motifs, clearly defined contours and live colours like strong blue, yellow and green.

stamped pattern in yellow and blue over the white background

stamped pattern in blue tones over the white background

geometrical pattern stamped in two tones of brown on the white background

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Relieved tiles

- While in Lisbon the bigger scale of stamped patterns were published, in Porto the relieved tiles were popularized, which characterized the tile production in this city, reflecting the influence of the moulding ceramics realized there in the 18th century. Forming a surface of plastic dimension, they have created effects of the light and brightness over the colour and the design, giving the volumetric suggestions to the facades. In order to maximally accent these light effects, the relieved tiles presented different colours for the motifs and for the basic layout. The tile surface, intentionally enamelled in white, was pained in a very coarse way with the opaque blue, yellow or green paint. This painting was determined only by the coloured volumes or smooth background, without any kind of pictorial effects.

High-relieved tiles

production was realized by mould filled with clay which would be manually made by fingers pressing. The most salient relief zones were pointed by excavating the clay from the tile, but trying to avoid possible deformations during the baking. The marigold (also called the rosette) or other floral forms, salient from the background, have turned into the dominant decorative motifs. The half-relieved tiles were not made conformably, but mechanically pressing the tile with a mould and a contra mould, resulting with finer plates.

Half-relieved tiles

- were produced by the factories Sacavém and Desterro, using a new white paste that was commonly used in the manufacturing of English dishes, known as a ‘’stone powder’’. This paste, white and opaque, ensued from steel less clay and mixed with grind quartz. The tiles appear to be covered with glass, colored in only one color (white, green, blue, yellow and brown) or not colored at all. They have spread along at the firs two decades of the century presenting some Art Nouveau motifs.

Beveled tiles

– were made in a rectangular form with beveled edges. They were glazed and produced in dark green, light and dark blue, yellow, cream/white, dark red and in some other tones of green and blue color.

high-relieved tiles – ‘’rosette’’ coloured in yellow on the white background

half-relieved tile – floral decoration coloured in blue over the white background

bevelled tiles in red colour

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MECHANICALLY STAMPED/PRINTED TILES Before the end of 20th century, the stamping gave in place to the mechanical stamping/printing, relieved from the recent industrial revolution, evident at the economics of materials and the chromatic palette and now reduced to only one color variant in tones. Decoration was applied by a stamp over a glazed stanniferous white tile (when the tile is made of plain clay). The chosen design was primarily pressed on the paper by a zinc plate and then on a tile for half of one press. At the end, a glassy transparent layer was applied to it. They are easily distinguished by monochrome stamp, in neutral or spiritless colors (blue, green, brown, yellow or pink are most frequent ones), on top of a white or beige chock. Printed tiles were using foreign design models, imported from England, France, Germany and Belgium, with the creations of new patterns which provoked spectacular growth of production. Nevertheless, the same pattern can have variances in color or design, which can be explained by the fact that different factories produced tiles with identical patterns, probably imported from abroad, or have had access to the same catalogues, or have simply copied them one from another. Art Deco, a rational and purified style influenced the tile production in Portugal in the 20’s and 30’s of the 20th century. The tiles of that period were characterized by the technical quality, formal expression and industrialized concept, while the forms were mostly geometrical with no volumetric effects and the design reduced to the graphic elements of rational construction. The compositions would result with the geometrically combined tiles in smooth colors.

pressed tiles with floral motifs

pressed tiles

Art Deco tiles

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4. Pathology and main anomalies of tiles The pathology and anomalies that can be found on the tile covering are many times directly provoked by bad state of conservation of the building which they belong to. It is necessary to observe and analyze the general state of conservation of the immobilities in order to give a clear diagnostics and prescribe the therapies necessary for the conservation and eventual restoration of the tile panels. Principal anomalies basically appear because of:

- Original defects

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– as a result of bad fabrication of the tile, use of low quality clay, deficient baking… Deficient setting of tiles on the panels

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- composition with errors, badly executed spacing, props under pressure, etc. Effects provoked by structural movements

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– rotation of foundations, for an example, can provoke some mechanical actions which can change the geometry of the supported walls. Humidity actions – coming from the wall itself or as a result of condensation.

original defect – bad fabrication

deficient setting

effects provoked by structural movements

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Mechanisms of degradation of tiles and their causes:

- Disappearance of glaze

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– caused by the presence of salt, lichens and human action of improper cleaning Loosening of the supporting layer

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– caused by the loss of mortar cohesion, introduction of plants or roots on the inside face of the stone, water infiltration or human action of removing tiles because of the ignorance, steal, selling or collections. Cracks and breaks

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– caused by variations in geometry of the structure, inadequate restorations, bad factoring processes, effects from frozen water or direct human action such as vandalism of any kind, Change of colours

– caused by graffiti’s or diffusion of conjunctive tints.

disappearance of glaze

loosening of the supporting layer

crack on the tile

change of colours

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5. Techniques of conservation and restoration The respect for the ethic principles of conservation (given in the Venice chart from 1964.) should be guaranteed in any case and it nominally refers to:

- Demand of the authenticity-

- historic, aesthetic, constructive and technologic. Demand of the durability

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– materials and techniques that question the long durability of old buildings should not be used. Demand of compatibility

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– the use of new techniques and materials can be indispensable for its conservation, so there must be guaranteed conditions for their reversibility and compatibility with the old building materials. Demand of economy

– the extreme economic conditioning in the operation of conservation can aggravate the problem or delay its resolution.

In practice, these principles are not always easy to apply because it is an action that needs to be pre-discussed between representatives of many other disciplines. However, there are some simplified options for the intervention of restoration.

1. substitution of unrecoverable tiles with new ones

2.

, done using the old technique by acknowledged artisans or specialists minimal intervention of replenishment of existing faults with the adequate mortar

3.

, which highlights ‘’in negative’’ the missing parts. The problem occurs when the quantity of missing tiles is very high or even prevailing the number of existing ones, the reading of the composition on the panel could be difficult to relieve. interventions of reintegration

– the total or partial replacement of the missing tiles with new pieces, which enables the reading of the composition from a far, but observed in detail, it can always give notion that it is in fact the intervention.

Some examples of inappropriate interventions

padding of the spaces with missing original padding of the space with missing original tiles with similarly designed tiles tiles with coloured mortar

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Before initiating any cleaning operation, conservation and/or restoration it is obligatory to proceed with following actions:

- Making of a complete photo register of the whole panel with tiles; - Marking the tiles with referent cotes that define their position on the panel.

Conservation and restoration ‘’in situ’’ – ‘’on the spot’’ is more defended for the fact that, once when is proceeded with the taking off the tiles from the wall, many of them end up broken. However, there are cases when their treatment is needed to be done in an atelier or specialized laboratory. Treatment and restoration ‘’In Situ’’ – ‘’on the spot’’ involve the following operations:

- Surface cleaning - Desalination and removal of the lichens and encrusted plants - Punctual consolidation – by injection of chemical products - Cleaning of the mortar on the inside face of single tiles - Gluing – for an example the glaze to the plate - Padding of the faults (with plaster or synthetic clay) - Painting of the faults in order to restore the legibility of the original composition

Treatment and restoration of the tiles outside the original support When the restoration of the tiles must be done outside of the original support, it has to be only if absolutely necessary, because the quantity of tiles that break or get damaged in the process of taking off is about 20%. So the lifting of tiles

is generally done when:

- is indispensable to treat the supporting structure - the mortar is very old and degraded and needs to be replaced - their state of conservation is so degraded that it can be resolved only in the laboratory - it is the last solution to guarantee their preservation (in the case if eminent demolition of

the building, for an example) Treatment of the supported structures and wall surfaces

generally involve:

- mechanical lifting of the tiles - complete removal of the old mortar - general application of a biocide - structural consolidation of the wall and most fragile zones - application of a wall plaster, remaking the geometry of the wall and preparing it for the

laying of already treated tiles Treatment and cleaning of the tiles

:

- cleaning the skin-deep dirt - cleaning the outdated glue - cleaning the concretions - cleaning the vegetation and removing the organic elements

Consolidation

- general or punctual

Setting up the tiles on the support

:

After the treatment of the support and the application of the biocides (if necessary) the tile have to be set up with a mortar based on air extinguished lime and sand. The finishing of the joins between tiles is done with a whitewash of same consistency coated over the tiles, and when it dries, the panel is cleaned with a cloth by removing the half opaque layer of the glaze. This system guarantees adequate junctions porosity of the water vapour and avoidance of damage caused by the water accumulation.

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Bibliography AGUIAR, José, Recuperação de azulejos, Construção Civil e Obras Publicas, Restauro e Reabilitação de edifícios, Guia do Formando AMORIM, Sandra Araújo, Azulejaria de Fachada na Póvoa de Varzim (1850-1950), Portugal, Edição de Autor, 1996. COSTA, Aníbal,; GUEDES, João M.; SILVA, Paula; PAUPÉRIO, Esmeralda, A Intervenção no Património Práticas de Conservação e Reabilitação, Porto, Faculdade de Engenharia da Universidade do Porto – Direcção Geral dos Edifícios e Monumentos Nacionais, 2002. LEMMEN, Hans Van, Tiles in Architecture, Inglaterra, Calmann & King Lda., 1993. MECO, José, O Azulejo em Portugal, Lisboa, Publicações Alfa, S.A., 1993. MONTEIRO, João Pedro, O Azulejo no Porto, Portugal, Estar Editora, 2001. VELOSO, A. J. Barros; ALMASQUÉ, Isabel, Azulejaria de Exterior em Portugal, Portugal, Edições Inapa, 1991.