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July 2003-July 2010InteractiveDig Sagalassos
One of the finished columns is taken to temporary storage.
A plaster cast of one of the missing archivolts
A giant "spaghetti" injects mortar behind the restored section of the (work)shops' back wall.
Mold of the Herakles bust
Nerina De Silva removes metal corrosion with a scalpel.
Katleen Van den Brande cleans an iron object.
Ines Vandewoestijne studying glass finds

Photos courtesy Sagalassos Archaeological Research Project. Click on images to enlarge.
by Marc Waelkens

Restoration & Conservation: August 3-9, 2003

The Antonine Nymphaeum

Preparation of the final anastylosis of the Antonine nymphaeum on the Upper Agora continued. The architects' team--Özge Basagac, Serpi Uyar, Emrah Köskeroglu, and Berran Sözer--continued trial fittings of the entablature parts of four of the six aediculae of the fountain on the newly created platform (see July 27-August 2). It became clear that during an ancient restoration of the nymphaeum, some columns and entablature blocks had been moved from their original position. In fact, the third and fourth aedicula seem to have been turned slightly outwards, so that even one of the soffits (decoration on the bottom part of an architrave) disappeared into the back wall. Meanwhile, the conservators--Sebahattin Küçük, Emre Basol, and Eftal Kiraz--continued the gluing of all column bases and most of the columns. This activity was supervised by engineer Paul Hostyn, who controlled the efficient application of the epoxy resin. The same team also produced a plaster cast of the archivolt of the first and second niche of the fountain's back wall, of which many parts are missing, to serve as a model for carving these elements. Toward the end of the week, most of the columns could be put together into a temporary storage place, whereas the column bases were placed in their original positions on the nymphaeum's podium.

On Site Conservation

Paola Pesaresi's team--Soner Bellibas, Esin Tekin, and, now, Maike Scholz (Center for Restoration Lemaire, KULeuven)--continued carefully pointing and sometimes capping the unstable walls excavated throughout the site. Most of their work still concentrated on the Domestic Area, but also included starting preparations for removing two corner blocks of the Roman Baths at risk of falling. In the Lower Agora, two stones from the Trajanic street fountain's arch that will be restored were removed for further treatment. In the northeast corner of the Upper Agora, they worked on a central section of the back wall of the late Roman to early Byzantine shops (see Upper Agora, August 3-9), where some ashlars had sunk after the mortared rubble section that supported them collapsed. The ashlars were lifted up mechanically, and supporting section was restored with mortar injected behind the stones.

Restoration of the Trajanic street fountain in the Lower Agora's northeast corner

As part of this year's site conservation program, the arch of a small Trajanic street fountain, built into the curved terrace wall along the Lower Agora's northeast corner. Last week, the fountain's keystone representing a bust of the moon god Men was already molded and cast for a copy by Stefano Volta, Erik Risser, Andrea Bosschi, and Matteo Chiandussi (see July 27-August 2). These activities continued this week, so that busts representing Poseidon, Athena, Zeus, Hermes and Herakles could also be copied. The molds of the latter were created by first isolating the original stone surfaces from potential contamination by chemical or oil substances in the silicone rubber molding material. A two-part barrier system was applied by brush, first a water-based oil barrier and then a synthetic fluorinated elastomer. Both substances are easily and fully reversible, the first coats the surface, blocking all pores, and the second prevents silicone oil penetration. After sufficient drying, the flexible mold was applied in two layers, a low viscosity silicone rubber suitable for complete surface coverage and high definition, applied by brush, then a layer added by hand to give greater thickness and reinforcement, increasing the overall tear strength and aiding resistance to deformation during storage. Because the flexible mold cannot hold its shape once removed from the stone surface, a rigid or mother mold is necessary to serve as a hard shell to hold the specific contours of the flexible mold immobile during casting. A polyester resin with catalyst and accelerator was used in combination with fiberglass matting to form a successive layer rigid mold. In total eight layers of resin-matting were formed by brushing the resin onto the flexible mold surface and then tamping the fiberglass matting into place until it became saturated with resin. Demolding was done in reverse of the molding process: removal of the rigid resin-fiberglass mold, removal of plaster wedges, and removal of silicone rubber flexible mold. Afterward all stone blocks were cleaned with acetone and water to remove both barrier layers, returning the stone to its state prior to molding. Casting was done in three parts. First, white cement, pumice, and red aggregate were mixed, approximating the stone's original color and texture. Once wetted this mixture was then brushed into the interior of the flexible mold. Second, a coarser cement mixture of more varied granular size was poured over this and then a custom-made welded stainless steel support armature was introduced. Lastly the armature was covered with more of the coarser cement mixture until the dimensions of the flexible and rigid mold were completely filled.

The Conservation of Small Artifacts

Artifacts are received and registered daily at the site laboratory. Registered entries usually consist of more than one find, except for the coins, and the average for a season is 240 coins, 400 iron, 90 copper alloy, 20 lead, occasional silver, 400 glass, 130 ceramics (sometimes representing hundreds of sherds), 100 stone, 300 fragmentary wall plaster and glass paste tesserae, 20 worked bone, and 35 varia. They're being looked after this year by conservators and students from the United Kingdom (Nerina De Silva), Turkey (Emine Kocak, Canan Ustabay, Filiz Zeyveli, and Melih Ekinci), Belgium (Katleen Van den Brande), and Kuwait (Abdul-azziz al-Duwaish). The artifacts are treated to varying levels depending on the condition and stability of the material and the requirements of the specialists; those artifacts selected for museum display are fully conserved. In general, following the principles of minimum intervention and reversibility, finds are treated to remove soil and corrosion products, using mechanical methods and carried out under stereo-magnification. Calcareous deposits on ceramics are removed with nitric acid; those on stone, mechanically after softening with water. Routine conservation treatments are recorded on a check-list type record slip, which is included with each object, and more detailed treatments on Conservation Record Sheets. This is followed by their storage in a controlled environment--metal finds except for bulk quantities of nails and clamps in air-tight plastic containers with desiccant silica gel, which together with the rest of the material is stored in insulated pre-fabricated containers.

[image]Bronze coin of Severina after cleaning

Coins and copper alloy objects selected for the Burdur Museum are treated by removing all corrosion products with scalpel and usually reveal a patinated secondary copper corrosion (green) surface that preserves the original detail. This is followed by immersion in a corrosion inhibitor benzotriazole (BTA) and coating with an acrylic resin preparation to protect the BTA-copper layer on the metal surface. Impressions are taken of the coins using a putty used in dentistry to enable their study by the numismatist. This year the glass finds were studied by Ines Vandewoestijne (conservation student, Royal Academy, Antwerp), who tried to clean all glass finds from previous seasons, whenever necessary also reconsolidating them before eventual storage, and worked to develop better storage conditions to prevent further corrosion, by using better wrapping systems and storage facilities. Some tests have been carried out, which will be checked next year.

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