WOOD CONSERVATION IN HISTORICAL BUILDINGS

The case of brazilian woods

Extended Abstract

Maria Francisca de Jesus Casimiro Sales Barreto

Thesis to obtain the Master of Science Degree in

ARCHITECTURE

Supervisor: Professor Doutor José Maria da Cunha Rego Lobo de Carvalho

Supervisor: Professora Doutora Ângela do Vale

May 2017

Introduction

This article summarises the thesis carried out within the scope of the master degree in

architecture, at Intituto Superior Técnico. The research process is result of an exchange

semester in Brazil combined with personal interest in the theme of brazilian woods, as well

the rehabilitation of historical buildings.

During the colonial period of Brazil (XVI-XIX), Portugal imported high quality Brazilian

hardwoods for textile dyeing, shipbuilding, civil construction and decorative arts. These woods

had high durability and strength and, despite the numerous references about them

exploitation and trade on the other side of the Atlantic, the use of Brazilian wood in Portugal

has not been much studied. There are some sporadic references to the alleged use of

"brazilian wood" in noble buildings (palaces or monasteries), but their verification and

documentation remains to be done. The present study intends to contribute to the study of

this theme, with the following objectives:

a) To understand the role of brazilian woods in the portuguese colonial period;

b) To frame the tradition of wood construction in Portugal;

c) Identify buildings in Portugal that used brazilian woods from colonial period;

d) Selec a case study;

e) Make brief considerations on the conservation and intervention of wood elements in

historic buildings.

Brazilian historical woods

Brazil's wood trade is immediately associated with the botanical specie pau brasil

[Caesalpinia echinata Lam], which has historically been the most exploited due to its high

commercial value for fabric dyeing. However, pau brasil was only one of several brazilian tree

species exploited by the Portuguese in the colonial period (OLIVEIRA, 2003).

At this time, commercialized woods were classified in three groups by naval carpenters:

soft woods, hard woods and "royal woods". The “royal woods” were known as the species

protected by law, where their exploitation and trade was exclusive to the Portuguese crown

(GONZAGA, 2006; 39). According to the chroniclers of the time, these woods were mainly

used in shipbuilding given their incorruptible quality. Examples of these species are: cedar

and vinatic (Fig. 1). Numerous documents from the Arquivo Histórico Ultramarino (AHU), in

Lisbon, confirm the shipment of wood to the Royal Navy Arsenal of Lisbon and also, for the

construction of royal buildings; but there´s no specifications of which ones.

Through documentary research in the main national archives and by analysis of historical

buildings constructed in the mentioned period, it was found that most of these buildings

suffered a fire or repair in which the original woods were replaced. The existent documents

about these buildings were very poor in terms of information about structural materials. Only

the decorative elements, such as the tiles and stucco, are the most documented.

Figure 1: Watercoler representation from 1742 of tree species: cedar (28) and vinatic (29).

Wood in Portugal

Wood has always been a present material in the Portuguese architecture, used in the

execution of structures in pavements, coverings and foundations. The Pombaline period, after

the earthquake in 1755, was probably the time were wood was being more intensively used in

construction in Portugal (APPLETON, 2003). Applied in the mixed system of wood structure

and stone, the "pombaline cage" consisted in a reticulated wall of high flexibility and energy

dissipation capacity with anti-seismic characteristics (Fig. 2).

In Portugal, the most used species in construction were mainly native, with differences

according to the region of the country. Unlike Brazilian historians seem to suggest, the use of

exotic wood in the post-earthquake civil construction was not significant. In the Pombaline

construction there are essentially wood of autochthonous species, such as: chestnut, cork

oak, evergreen oak and pine. When imported woods were used, the species found were:

scots pine and pitch-pine, from central Europe and North America, respectively (APPLETON,

2003). In this study was found exoctic wood in only one Pombaline building. The exoctic wood

was applied to the steps of the main staircase, however, without certainty of the species or

origin (APPLETON, 2009). Exotic woods in Portugal are more commonly found inside

churches or applied in carpentry works such as chairs, carving and tribunes (SMITH, 1962).

In an attempt to deepen this theme and try to confirm the use of exotic wood, imported in

the colonial period of Brazil, several buildings of the period were studied trying to find a case

study.

Fig. 2: Typical wall structure of a pombalino building.

Case study - Pombal Palace

History of the Pombal Palace

The case study of Palácio Pombal is located at 79 Rua do Século, Bairro Alto; one of the

first planned neighborhood of the city of Lisbon that, due to the good quality of the

construction of its buildings, survived without great damages to Earthquake of 1755.

Pombal Palace or Carvalhos's Palace is a building from the second half of the 16th

century, where Sebastião José de Carvalho e Melo (1699-1782) was born and lived; also

known as the Marquis of Pombal; Secretary of the State of Internal Affairs of the Kingdom

between 1750-1777. According to Irisalva Moita (1968: 49) this building was the favorite

residence of the Marquis of Pombal, which explains his constant investment on it and could

justify the use of Noble in its construction, during a period of great importing activity from

Brazil, as previously mentioned. Also temporarily lived in this palace, two important traders of

the colonial period - Gerard De Visme and Jâcome Ratton - related with the Brazilian wood

trade and the exotic tree plantation (LUCKHURST, 2014). The importation of brazilian wood it

would not be difficult for these two merchants, however, no references were found about

reformulations in the palace using Brazilian hardwoods in the period in which they inhabited

the palace.

At the beginning of the 20th century, the palace is successive occupied by several

institutions that contributed to the degradation of the building. In 1968, it is acquired by the

Municipality of Lisbon (CML) that executed some reforms of conservation and restoration.

Later in 1993, was classified as Public Interest Monument.

Since 2009, the building has been shared between the Municipality Galleries1 of Lisbon

and the Center of Art and Research - Carpe Diem, that use the space and guarantee its

maintenance (BALSINHA, 2011).

Figure 3: Exhibition in the Blue room of Pombal Palace.

1 The Municipality Galleries of Lisbon it is a department of EGEAC that is in charge of the management of exhibition spaces of the CML.

Woods of Pombal Palace

When visiting the interior of the Pombal Palace it is possible to verify the presence of

various wooden elements used in structure and coverings. At first sight, different species of

wood were observed, in their tonality and design of the veins and dimension (fig.4 and 5).

Figure 4: Wooden pavement at the ground floor.

Figure 5: Wooden pavement at the first floor.

In order to confirm that the Pombal Palace preserves in its interior exotic wood imported

from Brazil during the colonial period, it was request at the General Direction of Cultural

Heritage the support of ‘José de Figueiredo’ Laboratory to collect an analyse samples of

wood in the palace. It was sought to remove samples of different constructive elements for an

overall analysis of the palace's woods.

The observation of the morphological characteristics of the wood is what allows its

identification. A magnifying glass is used to observe the main anatomical elements of the

wood, and for the visualization of all the elements, even the smallest ones, it is necessary the

microscopic observation. However, it is not always easy the identification of the species

(ESTEVES, 2001).

The native woods, most common in the construction in Portugal, were easily identified as

to the genus (Pinus, Quercus, Castanea and Taxus); As opposed to exotic woods, of which

only a few have been identified (Bowdichia, Carya and Hymenaea). Nevertheless, two genus

corresponded to species of some "royal woods" trade by the Portuguese: sucupira [Bowdichia

sp.] and jatobá [Hymenaea sp.]. For a more accurate taxonomic identification it will be

necessary to compare with other collections of wood, existing in the other national libraries, or

a molecular analysis.

It should be emphasized that these samples also revealed the advanced state of

degradation of some wood elements, in particular of the autochthonous species, which

confirms the superior quality characteristics of the exotic woods.

The existence of exotic wood in the Pombal Palace raises interesting considerations

regarding its conservation, namely by its difficult substitution for other woods of the same

species or characteristics, when in poor state of conservation. Despite its physical condition,

its value as a testimony to the Portuguese colonial past and the history of construction is also

an important factor to consider in rehabilitation (OLIVEIRA, 2003).

In this sense, rehabilitation interventions of historic timber structures should consider a

specific methodology that includes, in particular, a rigorous architectural survey, identification

and exhaustive characterization of the materials and a historical and documentary framework

that justifies the project options, namely the preservation of original elements as a contribution

to the material authenticity of the buildings.

Final considerations

The knowledge of the species and the characteristics of the woods is fundamental for

better and justified interventions and contributes important knowledge to the history of science

and construction. As such, intervention criteria are required in historic buildings that

contemplate a complete study of pre-existing woods.

Although exotic woods were found in the Pombal Palace, possibly coming from Brazil; In

general, the use of Brazilian wood in Portugal seems to have been insignificant; However, it is

important to deepen this study and understand its real use in shipbuilding and civil

construction. As such, the analysis of construction documents of the main national

monuments (palaces, churches and convents) of the eighteenth and nineteenth centuries,

may be a way of perceiving the materials used in their construction.

Finally, the exact identification of some woods of the Pombal Palace remained to be

determined, since due to the scarcity of time and means it was not possible to identify all

species. It would be interesting to conclude this identification using the wood librarys of the

Superior Agronomy Institute (ISA), the Tropical Botanical Garden (JTB), the Lisbon Academy

of Sciences and the National Museum of Ancient Art (MNAA).

Bibliography

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Pictures Credits

Figure 1: Watercoler representation from 1742 of tree species: cedar (28) and vinatic (29).

AHU – Catálogo de Castro e Almeida. Bahia. Col. cart. - icon., Doc. 13768-13815. Relação das

madeiras que se encontram nas matas do termo da vila da Cachoeira, acompanhada de quarenta e

seis estampas aguareladas, feita pelo juíz de fora, Joaquim de Amorim Castro. 1790.

Fig. 2: Typical wall structure of a pombalino building.

Font: APPLETON, 2009: 28.

Fig. 3: Exhibition in the Blue room of Pombal Palace.

Font: carpediem.pt