Date: Argaric culture, 1800–1500 BC[P1]
Provenance: Cerro de los Castellones de Laborcillas, Morelábor, Granada
Inventory number: 1935/4/CLAB/1/5
Media, technique: Cast copper and tin dagger and silver and copper rivets
The object was broken into five pieces, three of them unconnected, all lacking their metal core. The dagger still had three of its four original rivets, in good condition and in their original location.
The dagger presented very extensive copper corrosion, with a high concentration of chlorides that had produced alterations in the corrosive process, leading to exfoliation, flaking and pitting with considerable material losses. Consequently, with the exception of the silver rivets, the piece consisted entirely of copper chlorides as its metal core had completely disappeared.
The primary goal of this intervention was to give the piece physical, chemical and structural stability. The first step was to remove the surface chlorides by hand, using a scalpel under binocular magnification, and subsequently halt corrosive chemical processes with an ethanol solution of benzotriazole. We also had to reduce the porosity and fragility of the brittle fragments, which we consolidated by immersion in acrylic methacrylate resin to improve their compactness and firmness.
The next aim of the restoration team was to arrive at a correct historical and technological interpretation of the dagger during the reconstruction process, a seemingly impossible task as the end fragments had no connection to the piece’s central fragments, making it difficult to determine the object’s original length.
Consulting the museum's Prehistory Department and Archive, which includes the more than thirty thousand documents in the “Siret Archive”, was essential for continuing our work, as the MAN archive contains a sketch by Siret of all the items in this lot of grave goods.
It gave us valuable information about the dagger’s contour for reconstructing the piece, but the most important detail for the restoration project was the description that Siret had added to his illustration: “Cerro de los Dólmenes de los Eriales. Grave goods from a burial and plan of the same. Knife with silver rivets; copper bracelet, silver earring. Life size. Pottery items drawn at half their size.” Thanks to this invaluable document, which indicates that the dagger was drawn to scale, we were able to determine that it was originally 193 mm long. This note beside the drawing of the entire outline of the dagger with its four rivets also revealed the distance between the unconnected fragments and the location of the missing rivet, which allowed us to reconstruct the piece.
Undyed epoxy resin was used for the structural fills and to join the fragments. Based on the extant drawing, and in order to respect the typology of the dagger with four rivets and facilitate its interpretation, we decided to create a resin reproduction of the hole that once held the missing rivet.
Finally, to give the piece a uniform appearance while also clearly distinguishing between the original material and the fills, we performed an aesthetic reintegration, applying wax-based colours in several tones in the manner of glazes.
The piece was kept under observation at the laboratory for several months; during that time it remained stable, and no new chloride blooms were detected. As a preventive measure, the piece has been stored in the Prehistory Department inside an airtight container with a relative humidity regulator.