NOTES ON SCULPTURE PROCESS

Jorge Palacios

In a way I confess I feel fortunate because my work as a sculptor and the day to day contact with the material let me grow very fast; I am well aware that it is not at all usual for the spheres of theory and practical work to move so much hand in hand. For me the knowledge of wood removes the limits to expression when creating, giving me the liberty to work on creations that can be situated outdoors. The technology of the material is a means for me to achieve a goal, a tool; without it, many of my projects would be limited or I would achieve results other than those I aimed at as a creator.

On the other hand, I understand the material I work with as a support, that must, at any time, adapt itself to the idea and the format of each piece and that must not restrict or condition the plasticity or the expressivity. In fact, wood gives my hands the feeling of being as mouldable as clay and it never conditions me towards certain volumes or formats. On the contrary, it gives me the freedom to work with it according to the requirements of each project.

Through these lines I intend to share some reflections and theoretic considerations about the technological preparation process I have devised, discussing some outstanding results we have obtained in laboratory tests, adding some other ideas about this singular sculptural process I have developed in the passed years.
As a sculptor working in wood to carry out my work it is very interesting to study some examples throughout history, and not only history of art, that highlight the  durability of wood, and thus through extrapolation and conclusion understand why these pieces still exist in our times and we can still enjoy them.

On the other hand historians usually consider that the degradation suffered by a piece of art along time is part of its history, although they are conscious of the fact that with this transformation part of the original information the author tried to reflect in it is lost. Personally, I am highly interested in preventing this information from being lost. The expressive, artistic value of my work should remain unaltered as much as possible. In fact, when planning different ways of conceiving a sculpture, I try to choose the most appropriate method so that the curves and tensions of each of my pieces last as long as possible in the same state I conceived them, using present day science and technology.

Advertisement

SELECTION OF WOOD SPECIES FOR OUTDOOR SCULPTURE

Jorge Palacios

Thinking in terms of durability and long term conservation most types of wood can be considered suitable for setup in indoor locations, as long as conditions of stable humidity and temperature are met, as is the case in contemporary art museums.

This would not the case for outdoor setups, and it is particularly useful for me to analyze the information available to set and put in context these approaches, since amongst the hundreds of species found in wood trade and the more than 40.000 from which you can obtain wood, just a few hold a natural predisposition and might be perfectly suitable for outdoor use.

This does not mean that these few species are incorruptible, since nature itself takes care of reintegrating them in the biological cycle. If we add the knowledge about how the degradation of these particular species takes place I believe some minimal preventive measures can be taken to render their structural longevity far superior to the rest. Applying this is of enormous interest to me in the field of the creation of outdoor sculptures.

In my opinion, as a sculptor with a deep knowledge of the material, and putting it quite simple, wood cracks or breaks because it moves more than what it can withstand, because the forces due to hygroscopic exchanges with humidity in atmosphere are greater than the maximum tension the elasticity of this particular wood can endure. This constant movement generates tensions, and added up to different factors that weaken the wood end up generating checks and cracks, or widening existing ones derived from the growth of the tree or the seasoning process.

For a sculptor working for the outside like me it is extremely important to understand what happens in order to solve certain situations. That is why I consider it fundamental to comprehend that, among the factors capable of weakening the structure of the wood there are biological agents, i.e. chromogenic and rot-producing fungi, mildew, insects  – xylophages coleopterans and termites – and abiotic agents like decay due to light, fire, atmospheric humidity and temperature changes, on top of chemical agents.

Likewise the inherent anisotropic characteristics of wood make these tensions I was mentioning uneven along one piece, and only if it was independent and could move freely would it be able to cope with the forces its own movement generates, without endangering its structural integrity.

An anecdote illustrating the notable forces and tension wood is capable of refers to the Egyptians, who, as astonishing it may seem, used wooden wedges to split stones; when they were moistened, they generated such forces that the stone would break along the line of wedges disposed.

When carrying out an open air sculpture parting from a solid block one of the basic principles I consider is that I am not working on one independent piece, but rather a collection of anisotropic parts of wood that generate different degrees of tensions due to their characteristic irregular movements. The success in setting up this block for sculptural purposes resides, according to my experience, in being able to minimize these tensions through two concepts: choosing a species with the highest dimensional stability and the design of the block (sawing strategy, seasoning and distributing the structures of the wood according to the setup of the block).

Thus, when choosing a species to sculpt my work, one of the top priorities I take into account is the different movements in axial, tangential and radial directions as well as the expansion and contraction coefficients. Not only should these values be as low, but also as similar as possible to each other.

To estimate and confirm what this means in practice and what implications these movements of the wood would have on a sculpture I have done an analysis on what dimensional changes different blocks of different woods would experience; 1m3 pieces undergoing an increase in internal humidity of 8%.

In this way I try to calculate how wood facing an extremely adverse situation would swell, starting from a 12 % internal humidity value, and considering that in standard atmospheric conditions in Europe the wood would hardly exceed a value of 20%. Therefore, this hypothetical situation would take place when the wood experienced an increase of 8% in its humidity content.

In this study, I have compared wood that presents highest movements (European beech) with that of one of the most stable species (standard teak), and with selected teak wood; we have obtained the corresponding values from tests performed at the Technological Research Centre Tecnalia Research & Innovation.

In the study, I have seen the usual dimensional changes in European beech wood*1, with a unitary tangential contraction coefficient of 0.50 and a unitary radial contraction coefficient of 0.30. In case of a humidity increase of 8% it would suffer an increase of 40 mm in tangential direction and 24 mm in radial direction. In comparison, we show the dimensional changes for standard teak wood*2; given a unitary tangential contraction coefficient of 0.27 and a unitary radial contraction coefficient of 0.14 it would suffer an increase of 21.6 mm in tangential direction and 11.2 mm in radial direction. Finally we show the changes that the teak wood I have chosen*3 would show; it has a unitary tangential contraction coefficient of 0.16 and a unitary radial contraction coefficient of 0.08, it would suffer an increase of 12.8 mm in tangential direction and 6.4 mm in radial direction; all these values are quite extraordinary and really uncommon and I must confess they made me really happy, since they were confirmed by the lab tests.

As a result of this study it appears that teak wood is a suitable candidate to carry out my sculptural work, due to its natural predisposition, the fact that it is highly resistant to abiotic and biotic agents – since it is so hard and chemically aggressive it is disliked by most xylophags and bacteria – and to the fact it presents exceptionally low expansion and contraction coefficients.

• *1. Various authors. Especies de maderas. Madrid: Asociación de Investigación Técnica de las Industrias de la Madera, AITIM, 1997. p.354 – 356.
• *2. Various authors. Especies de maderas. Madrid: Asociación de Investigación Técnica de las Industrias de la Madera, AITIM, 1997. p.650 – 652.
• *3. Laboratory tests done by Tecnalia Research & Innovation according to UNE 56533:1977 on teak wood samples provided by Jorge Palacios.

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.

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.

Since 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.

REFLECTIONS ON THE SAWING FOR OUTDOOR SCULPTURE

Jorge Palacios

It is noticeable that in traditional way of wood sawing in industry the logs are moved, for example by a conveyor, and fixed by grips or claws to a cart and moved across a band saw cuts the first plane. This initial plane is usually not well aligned with the axis of growth of the tree, so all subsequent cuts aligned with this first one will not be aligned with the nucleus, and consequently all planks obtained will have their fibre slightly misaligned.

On the other hand, it is possible to find sawmills with the necessary technology to align the centre of the nucleus with precision at one end of the log before cutting the first plane, but for this to be really useful, it would be necessary to do so on both ends.

So I think that, since the logs show more or less strong deviations of their growth centre in relation to their geometrical centre, taking some simple measures they could be drawn into the band saw aligned precisely on both ends; this would produce wood with aligned fibre, independent of the original misalignment of the nucleus of each log.  This is very seldom found in industrial processes, but as a sculptor I believe this would represent a big advancement in the wood transforming sector, achieving a higher quality.

Thanks to the contribution of the scientists and prestigious experts that have worked with me over the past years I have managed to develop a sawing design for its use in exteriors; this design has been verified innovative by the OEPM (Spanish patent office) and has been accepted to the patenting process.

As one can see this cutting design does not take into account the pith to make a sculpture, since it will often generate the well-known heart- or pith cracks, due to the different density in relation to the rest of the log. I would also discard the bark, to avoid illnesses and fungi in the wood, as well as the sapwood because of its different colour which would stand out too much in the overall assembly of the block, and also because it has different characteristics from the rest.

The key feature of the cutting design I have developed is that it must be applied to trunks that have been aligned on both ends, in such a way that when rotated or put together they would necessarily have similar location of their growth rings along the whole piece, or in other words, wooden strips or pieces homologous to their neighbouring pieces in the block’s configuration all along its long axis.

Curiously, when building structural beams one very often finds pieces glued along the heart or tangentially; the purpose of this is to contain the traction during shrinkage and expansion movements. Basically this is a correct theory, in my opinion, since it is based on physics laws saying that diametrically opposed forces of same magnitude annihilate each other, and I would totally agree with this way of arrangement, if it was not for a small detail: from my point of view as a sculptor, in practice there always will be slighter bigger force, and thus tension, in one of the pieces we arrange together.

Therefore, from my experience I have designed a way to build up the block where the pieces, already subject to a continuous movement due to shrinkage and expansion, should not try to fight forces between each other thus generating added tensions and a continuous stress. In this way, in my opinion, we could avoid the pieces from ending up breaking faster than if their forces did not oppose in such a direct way and could free part of the tensions performing the movement inherent to the contraction and expansion.

What I put forward as a result is that, if the pieces must move, they do so without encountering opposing obstacles or tensions, but that they all do so in the same direction and in a similar way, so that tensions within the block are minimized, as far as it is possible.

BASIC CONCEPTS ON THE DRYING WOOD FOR SCULPTURE

Jorge Palacios

A question that is often put to me is why instead of sculpting directly into a big solid trunk I saw it into planks or strips and compose a block again. The fundamental reason for this is that it would be almost impossible to season (dry) it in a uniform way as a whole, and the wood would have different humidity percentages in the inner and outer parts. The excessive humidity in the interior could lead to rot too.

I still remember my surprise when I learned that with the traditional technology of wood seasoning in the drying chamber the deepest uniform drying possible was only 5 cm; now everything was clear. My constant obsession to find big trunks e.g. big trees knocked down by the wind or removed from public places, proved meaningless, since it would be impossible to season them correctly, and I understood this was the reason why wood was always found as planks in commerce.

Therefore, if our aim is to guarantee the structural integrity of the sculpture to be created from this material the most appropriate thing to do would be to saw the trunk into planks of a maximum thickness of 10 cm, achieving in this way that the innermost part of the piece would not be more than 5 cm away from the surface.

Nowadays there are several methods of seasoning, among others: drying chamber, vacuum seasoning, with microwaves or simply in the open air. Concerning this last method, if we tried to dry a trunk in a natural way in the open air, depending on species and climate, it would generally take about 1 year per each cm on average, rising to 2 years per cm from 10 cm depth on. This means that a 50 cm radius trunk would need about 90 years to reach an acceptable degree of humidity, but even so during this process it would undergo dimensional changes and crack due to the pressure appearing between the rings in the shrinkage and expansion processes.

Among the seasoning procedures I believe the chamber method is best, since you can control the temperature and humidity changes applied to the material with precision.
A fundamental premise of the seasoning is the need to adapt as much as possible the percentage of humidity of the wood as much as possible for the intended service and humidity during use in the location where it is going to be set up, since the bigger the difference between the humidity of the wood and the average annual humidity of the chosen location at the moment of setup, the bigger the risk the sculpture will endure during the acclimatizing time; its in this time that the wood will look to find by itself the hygroscopic equilibrium humidity (HEH).

To highlight the importance of this aspect one might think of the specialized transport of pieces of art between museums, where certain sculptures made of sensitive woods are moved in special climate-controlled chambers and where a very slow acclimatizing process to their new location is respected, in some extreme occasions for extremely delicate works, where the transport containment is open 1% a week before the piece of art is removed from it. In fact, one of the premises of museum conservation is the strict control of relative humidity and temperature of their premises, heavily insisting on the most important factor: the avoidance of radical changes of these parameters.

During this acclimatizing time to the conditions of use for a certain wood species the hygroscopic factor plays an important role, it is the ability of a species to exchange humidity with the atmosphere. One must understand that not all kinds of wood exchange humidity at the same rate; this is dependent on the intrinsical characteristics of the cellular walls of each wood, so according to each species the speed of this interchange will vary substantially. Although these small changes in humidity content may not be significant and affect the state of the piece of art in a critical way, you must consider that wood does not attain its Hygroscopic Equilibrium Humidity instantly, there is a certain delay in relation to the environmental conditions due to the inherent inertia in its permanent adaptation to the environmental conditions; in a non controlled climatic environment this generates an out of phase condition between the required humidity degree and the real degree attained by the wood, since usually climatic conditions vary faster than the time wood needs to adapt its humidity.

Another curious fact is that when the wood attains a humidity degree above 30% its cellular walls are saturated with water, thus even if it absorbed humidity above this value it would not undergo any substantial dimensional changes. On the other hand if humidity falls below 30% the cellular walls start dehydrating, and therefore a contraction proportional to the humidity loss will take place, reducing the global volume of the wood.

To finish I would like to insist on the fact that a correct method of sawing and seasoning of the wood may be just as important as the choice of the species we are going to work with.

As one may have noticed throughout these lines, as a sculptor I could talk for hours about a material I love and understand – wood. Allowing it the responsibility to express and voice the things that move me, and that I can hardly put into words.

WOOD AS DURABLE MATERIAL FOR OUTDOORS SCULPTURES

Just as there are types of wood that do not burn and others that do not float, so there are woods that are especially resistant to the passage of time.

Through the History of Art, we know of the existence of sculptures made of wood that are still in a good state of conservation today. The most representative examples of such items are:

• The Shiguir idol, the oldest wooden sculpture in the world, dating from 7,500 B.C. – the end of the Mesolitic period – wich is on display in the Keyaterimburg Ethnographic Museum in Russia.
• The famous Egyptian wooden sculpture, Sheik-el-Beled, made around the year 2,750 B.C., wich is currently kept in the Cairo Museum in Egypt.
• It is thought that the oldest wooden sculptures sited outdoors that have been preserved may be totem poles sucha as the following:
• Haida wooden totem poles from British Columbia (Canada), that are at present on show in the Musée de l’Homme in Paris, France.
• The great Polynesian sculpture in the Rockefeller Collection in the Metropolitan Museum of Art in New York, in the United States.

Leaving sculpture aside, there are also numerous examples of houses, temples and ships built of wood thah, even though at the time the specific treatments and knowledge we have today were not available. The following are some representative examples of such constructions:

• The Horyuji Buddhist temple in Ikaruga, Japan, wich dates from the year 670 and possesses the oldest buildings in the world. It has been registered as an UNESCO Worl Heritage Site.
• The Oseberg Viking ship dating from 820 A.C., currently in the Viking Ship Museum in Oslo, Norway.
• The Baoguo Temple, also known as the Linshan temple, wich dates from 1013 and contains the oldest wooden structure in the whole of China.
• The famous Torii (gate) of Itsukushima, Japan, dating from 1,170.