Architectural Restoration Criteria in the Maya Area

Materials

Prior to referring to restoration materials, I think we should explain now one word we have been using frequently: the word structure. Generically and according to the dictionary, this term is defined as follows:

STRUCTURE:  Distribution, arrangement and linking of the parts of a whole.
(Dictionary, Encarta Encyclopedia 2000)

In a purely literal sense, any product of nature or humans could be named with this word, but in the archaeological world the term "structure" has long been applied as a generic word with which we may denominate any construction, provided that parts thereof do integrate a whole. We must outline that this is a term with a strictly generical use, in a way that it has no relation with the social function it may have played in antiquity.

The terms "palace", "temple", "residence", "patio", or "plaza", etc., are terms denoting a social function, and therefore we are unable to use them as long as the archaeological investigation is not completed, which would explain in turn the use the structure in question may have originally had.

An additional, important aspect, is to explain that the structure or fabric of Maya buildings work in a very different way than modern buildings and designs, as they are fulfilling different physical principles. In Maya buildings, balance is the major issue, one that is achieved not through a rigid internal frame but rather with the organization of materials in such a manner that the whole may acquire "balance". In mathematical terms, we could say that construction materials are placed in such a way that its "moments" are annulled and equal zero (R. Larios 1997:11).

In virtue of all this, we understand that the stability of Maya structures does not depend on the strength or weakness of mortars, because even though exceptions exist, the most usual is to find clay muds or weak clay mortars, or merely lime, used as agglutinants. The superficial linings such as flattenings, stuccoes and floors, were almost always manufactured with top quality clay, as they had a clear understanding of the fact that water filtrations were to be avoided at all costs.

The mortars used, disregarding the component material and applied with abundant wedges of hard and thin stones, is only of help for achieving that perfect balance in the organization of stones, as refills, constructive support masses, or in the layout of the final walls.

Modern building techniques, together with our present notion of the structure and the available materials, has influenced many restorers of prehispanic buildings, making them use strong materials such as concrete mortars or iron bars (like in Kahal Pech, Photo 15), in an attempt to achieve stability through the strength of modern materials. However, the Maya structural foundation has little to do with the toughness of the agglutinant.

Click on image to enlarge

As an extreme example, let me show you Photo 52, above, an experimental arrangement of scale-cut stones, on which no agglutinant or mortar has been used. Stones were organized merely with small wedges until the desired balance was achieved, and there are five courses one on top of the other breaking the vertical position, imitating a portion of the Maya vault (Copán, October 1986).

Mortars

Having clarified this matter, no doubt it will now be clearly understood why we recommend to avoid, whenever possible, the use of Portland concrete in agglutinant mixes, turning preferably to lime mixes of the best possible quality. We know that it is not easy nowadays to obtain quicklime, or caustic lime, as in production places they’d rather sell hydrated lime or calcic hydroxide. Nevertheless, it is much better to try to obtain quicklime, to have the chance to hydrate it on the very spot. In this way, quicklime is placed in a washtub or large wooden box while abundant clean water is poured on top of it allowing to personally control the chemical reaction. This allows to eliminate the stones that do not react correctly, and so we have the chance to keep the best lime.

In the hearth, fire transforms the stones or calcium carbonate in calcium oxide, or quicklime, and this in turn, when wet, reacts and is transformed in a calcium hydroxide, slaked or hydrated lime. (This is something different than hydraulic lime, obtained from stones of calcium carbonates and a percentage of clay, and which hardens when contacting water).

Lime’s capacity will depend on three factors: the kind of stone, the temperature and homogeneity of calcination in the hearth, and the degree of hydration. It is advisable to leave it submerged in water for the longest possible period of time. In special cases such as repairs and stucco fixations, lime is to remain in water for at least one to three months, but whenever possible, for one year or more. This kind of treatment will yield a top quality calcium hydroxide. For what I know, it is possible in México to obtain chemical lime with a remarkable degree of purity, and restorers of movable goods recommend it as a special material.

If the preceding possibility cannot not be put into practice, hydrated lime in commercial bags may be an acceptable agglutinant in the preparation of mortars for reintegration, or for the integration of ashlar stones during work. Needless to say, if our work includes footpaths for the passing of thousands of tourists, perhaps concrete would be an appropriate material; but for restoration purposes, we should use a material compatible with the original one. Three parts of sand or sascab, in limy areas, and one part of lime, will yield an acceptable mix. If lime’s quality is very poor, we could exceptionally use concrete in a proportion that should not exceed 5%.

Ashlar Masonry, or Stone Blocks

In architectural restoration we are required to use compatible and not contrasting materials, to avoid changing the color, shape, or texture of the monument, so whenever we have the original stones at hand, there’s no reason not to use them in the same way as they were originally arranged. Nevertheless, the mark of our age is required. Thus, we shall be maintaining an integrated look while simultaneously those who are interested or have some degree of knowledge may, through a closer inspection, differentiate the integrated parts or complements, as also the evidence that led to the undertaking of such actions.

We have previously said that there are no specifications for the restoration of Maya or prehispanic monuments. Nonetheless, I have found an interesting document titled "Especificaciones Generales de Restauración" (General Specifications for Restoration). It is not focused on archaeology, and was published by the Secretaría de Asentamientos Humanos y Obras Públicas de la República de México, México, D.F., 1981 (Human Settlements and Public Works Secretariat, Republic of México). Mostly, it refers to colonial and historical monuments.

We have also explained that in a way, the foundations for restoration and the conceptual aspects of colonial monuments are more or less the same than those for prehispanic features, and that they basically differ in the social function that the monument serves nowadays. Under that light, and interestingly, this is what the document literally states:

4.01 ROCKY MATERIALS:

4.01.1 Natural stones.– They must be similar to the original ones in geological provenience, color, dimensions and texture. The attempt should be made to locate the precise source; if this is not possible, the most possible similar materials shall be used. Whenever the original stone happens to be remarkably frail, replacement with a tougher material is recommended, though its appearance should be similar to the desired one.
(Especificaciones Generales de Restauración, pg. 17)

As seen, also in colonial restoration, the criterion is not to change the color and texture of the integrated portions. In this case, and as previously stated, the use of rubble stones recovered during the investigations is the best possible material to reproduce the original fabric, provided it exhibits the mark of our age which should be visible under close inspection.

The opposite situation would be the absence of stone originated in the ruin, because this has been completely destroyed for its softness and the fall suffered at the time of collapsing. Tikal, Xunantunich, El Pilar and other sites in the area are typical cases where the original stone was so soft that at the time of its fall during collapse, it was turned into powder or fractions so small that they will prove insufficient to restore. In this case, my advice is to proceed as previously stated. An alternative source of materials should be located to fulfill the necessary specifications.

Of course, if we work carefully, we may find some original stones in an acceptable state of preservation. It would be a pity to dispose of them. In my view, we should use them, if possible, and we should even try to understand where do they come from, to attempt a reintegration.

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