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Stucco Relief from Structure XIX, Palenque
Treatments Applied (…continued)
The fragments found among the rubble were subjected to the following procedures:
- Search for the original location of the fragments (see photo 42).
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Click on image to enlarge
We searched for the joints between the fragments to conform elements of a larger dimension (see photo 43, above); once the joints were located, the pieces were placed in the sand bed for handling and to obtain the same surface level, as the thickness between one piece and the other was variable and the sand allowed us to handle them without causing damage to the edges (see photo 44, photo 45, photo 46 and photo 47).
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- Assembly of fragments in an attempt to form blocks (see photo 48).
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As the joints of the stucco fragments began to be found, they were adhered with Mowithal B60H, with the aggregate of ceramic fiber to provide a greater resistance and they were later attached to the fragment detached from the pilaster (see photo 49 and photo 50, shown below). The fragments were placed on the sand bed (see photo 51, below).
The fragments with smaller dimensions were attached with casein glue. 2
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Click on image to enlarge
- Assembly of fragments found in the rubble with the fragment detached from the pilaster.
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Click on image to enlarge
Once the place of each fragment was defined within the broader stucco relief, they were joined together with the rest using a synthetic glue with a load of ceramic fiber as an aggregate, to give the gluing a greater resistance, and work continued on its assemblage, both in the front and back, using a wooden grid and a plate of polyurethane resin as a support (see photo 52, above); this enabled us to add the fragments that surrounded the detached portion working on both sides (see photo 53, shown above) by placing provisional supports of polystyrene sheets in the areas where new fragments were being added (see photo 54). The sheet of polyurethane foam comprised only the space of the area detached from the wall (see photo 55, below and photo 56).
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- Repair with ribs paste.
Repairs with ribs paste were accomplished in the fragments that were being assembled, both in the joints and the space between fragments (see photo 57), considering that this paste, when melted with a soldering iron, provides a greater resistance for movements as well as a greater flexibility (see photo 58).
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- Joint repairs with ceramic paste.
Once repairs with ribs paste were completed, we proceeded with fine repair using a ceramic paste (see photo 59); this paste was also used to complete a number of forms (see photos 60 and 61, below).
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Click on image to enlarge
- Assemblage of pastillaje fragments.
Parallel to the process of repairing with the ceramic paste, we began with the process of assembling the fragments of embroidered clay (pastillaje) by using Mowithal B60H as an adhesive, to later continue the repairs with ceramic repairing paste (see photo 62).
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Once the assemblage of fragments and the repairing process were completed, we concentrated on the steps necessary for placing a permanent support.
- Protective cover with aluminum foil.
With the purpose of preventing the resin that was to work as a provisional support from penetrating the stucco, a layer of aluminum foil was placed on the entire surface (see photo 63) to seal it, and we verified also that the paper had no perforations (see photo 64).
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- Polyurethane foam layer.
This was uniformly applied on the entire surface of the relief, which had been previously partitioned to hold the resin in place (see photo 65); once the layer had fully reacted, it formed a hard and enduring surface that absorbed movement, additionally providing the advantage of having the precise shape of the relief, so it did not move (see photo 66).
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On top of the polyurethane foam, a plank was positioned and tied up to the wooden frame, and then the entire stucco panel was turned over (see photo 67), enabling us to proceed with the necessary treatments on its back, to prepare the piece to receive its permanent support (see photo 68).
- Leveling and repairs on the back side.
With the purpose of obtaining a semi-uniform surface in the back, the largest protuberances were mechanically removed with a surgical knife; later, the cracks and fractures were repaired with ribs paste, heating the largest ones with a soldering iron, and treating in the same way every small hole observed in the stucco (see photo 69).
- Calcium caseinate layer.
This layer was applied with a brush trying to fully cover every single space with this solution (see photo 70).
- Insulating layer.
As an insulating and reversible layer, a cheesecloth cover was applied using calcium caseinate as adhesive agent, and subsequently an additional folded cover was applied using once more cheesecloth and calcium caseinate as an adhesive agent; both were applied with a brush (see photo 71 and photo 72).
- Permanent support.
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The structure added to the stucco relief, which is its present support, was made of aluminum ribs in a three-dimensional framework (see photo 73, shown above) fit to resist the weight of the panel, and was cemented with a layer of epoxy resins which provide the stucco relief a new museographic support (see photo 74, below).
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- Finishing of the edges.
With the purpose of making the support of araldite resins look like stucco, a layer of ceramic repairing paste was uniformly applied all along the edges.
- Fixing the pigment.
The pigment was fixed so that it wouldn’t fade away with the passing of time, as a consequence of abrasion or friction of any sort (see photo 75).
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- Reintegration of color.
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Mineral pigments were used to attenuate the visibility of the repairs so that they would not be obvious to the eye (see photo 76).
The preservation and restoration works for the stucco relief found in the central pilaster of Structure XIX concluded with the process of color reintegration.
Click on image to enlarge
Endnote:
2 We started using casein glue as adhesive agent, but with the extreme climatic changes that took place during this field season we found that this adhesive was unfit for the functions required, and therefore we replaced it with another one of synthetic origin.
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