TECHNICAL SELECTION OF CHARACTERISTICS OF THE SPECIMEN

Jorge Palacios

From my point of view, and with the aim to obtain the technical qualities that guarantee a higher stability and duration of a wooden sculpture bound to be setup in the open air, it is important, especially for me as a sculptor: to know how much the wood will move, to pay attention to how it moves and, most important of all, which elements participate in this movement. This means to identify the singularities that affect the wood in this way, how much they affect it and how the tensions that are generated are.

Selection of wood material for outdoors sculptures When we talk of wood we are talking about an anisotropic material; this means its movement depends on the orientation of its cells, the lower its heterogeneity the more predictable and constant its movements may be, so as a consequence there will be less tensions between the cells.

Small burgeons, big knots, the pith or its deviation along the growth line of the tree are elements which can generate uneven tensions in the ligneous structure of the wood during contraction or expansion, since they are configured slightly differently from the whole on a cellular level. In fact, some of these singularities not only generate anomalous structures in terms of disposition and morphology of its cells, but they can also uneven compositions between cells of different typologies.

Therefore, I would like to share that, in general, different morphologies with different dispositions generate unequal physical and mechanical behaviour, in other words, this would indicate that a uniform ligneous structure of the tree would generate a uniform movement in its wood. This is why I consider that these behaviours one can see in the cellular structures may be extrapolated and may be reproduced in the design of the assembly or the building of a wooden block. All the pieces composing the block would be as similar as possible to each other, obtaining behaviour of all of them as if they were in some way one only piece.

As a son of two technical agronomical engineers, and since I must consider the botanical point of view, I believe in the fact that wood is a material with singularities being part of its own nature; trees logically have branches, and therefore knots, and from this detect specific singular species, that tend to develop their crown at a great height, whose trunks are usually free from branches up to the beginning of the crown, so they present a highly marked vertical growth. They usually produce wood with very straight fibre free of branches and knots in the first cuts of the trunk, which is usually the case with teak wood.

Within the preparation process of a block for sculpture purposes and in order to obtain the most uniform possible wood morphology it is in my opinion of highest importance to perform a strict selection and discarding of the specimens, and among them, a cleaning of each cut log or board. This preparatory work can be simplified by the choice of a species presenting a natural predisposition to this purpose.

Teak wood for outdoors sculptures by Jorge PalaciosSince a tree develops its technical characteristics and performance in an optimal way when arriving at maturity, when selecting the individuals for sculpture the homogeneity of the whole could be compromised if mature and young specimens were mixed. It is more advisable in my opinion that all individuals stay within a logical age interval. Within the same species individuals coming from the same geographical region will present more similarities, having grown in similar latitudes they will have been submitted to similar climatic conditions. Other concepts, like differences in altitude and the composition of the soil may be the cause of slightly different developments in growth for the same species.

It is also quite remarkable, that in the forest, when a big tree falls it leaves a clearing, and all the other trees living on the edges of the clearing redirect their growth towards the light. This creates a deviation in their growth line, thus their growth rings decompensate and this creates an anomaly in relation to the other specimens of the forest. The same thing happens when a specimen is displaced briskly by climatologically adverse causes, giving birth to certain singularities in the wood, like deviated or crossing nuclei. I consider that these anomalies must be identified and discarded during the process of preparation of a block for sculpture before sawing.

As we know, usually a tree’s heartwood will deviate from its geometrical centre, sometimes due to its geographical location, to the fact of growing on steep hillsides, for being exposed to repeated predominant winds. This intrinsic characteristic of the tree’s own nature is different from the one I mentioned before, which caused an important change or deviation in the natural growth, and should thus be considered a singularity or anomaly.

Taking these concepts into account, and considering the fact that all the fibres of the tree are aligned with its nucleus it seems obvious to me that for this purpose the most appropriate way of sawing should start from the growth nucleus. Later it would be possible to align all these fibres in the block, after having corrected all trunks with misplaced or deviated centres, but not the ones with a heavily curved nucleus on the inside.

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