Bronzestøbning i dansk Jernalder

Bronzecasting

Jysk Arkæologisk Selskab 1986-10-16

 
Bronzecasting This article presents the results of experiments with bronzecasting in Iron Age context, carried out in connection with the reconstruction of the Langå Waggon, a Funen version of the Dejbjerg waggon type. The experiments have been carried out by Fyns Stiftsmuseum and Historisk Værksted, Næsby. The processes employed have been based on written medieval sources (1) and archaeological material illuminating the prehistoric casting technique. This comprises crucibles, mould parts, parts of bellows, casting waste and the actual casting pits where melting and casting have taken place. For the moulds, loam has been used, in order to obtain a material which is stable in shape. The proportions depend on the grain sizes of the materials used. In the present instance, the blend is c. 60 % sand/gravel, c. 35 % clay and c. 5 % organic material. It is desirable that there be as large a quantity of quartz (4), the heat-resistant part, as possible, although clay is of course necessary to bind the quartz grains together (5). The moulds consist of several parts, the parting faces serving as "air vents". In order to use a loam mould for bronze-casting, it has to be fired, or it will shatter during casting. Likewise the temperature of the mould at the moment of casting is critical (700°C) (Fig. 5). During the firing, all oxygen in the crucible is consumed, and the body is therefore reduction-fired and black. The black colour is thus a result of the firing and not of the heat from the bronze at the moment of casting. The outside is open to oxygen during the cooling and is therefore yellow or red. Melting proved to occur best in a pit, c. 20 cm in diameter and c. 20 cm deep (16). During melting, concavo-convex pieces were formed on the sides of the hole, the concave side becoming vitreous (17) (Fig. 10). The metal and crucibles were in the present experiment both of commercial origin. These crucibles of fireproof clay could withstand only 3-5 melts however, before they broke

Bronzestøbning; jernalder; danmark; rekonstruktion; eksperimental arkæologi; langå vogn; bronzecasting; iron age; denmark; reconstruction; experimental archaeology; langå waggon; info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion

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Kuml; Årg. 34 Nr. 34 (1986): Kuml 1986; 77-94 2446-3280
Danish

EDA oai:ojs.tidsskrift.dk:article/109809
https://tidsskrift.dk/kuml/article/view/109809
10.7146/kuml.v34i34.109809
1257578439

ROYAL DANISH LIBR AARHUS
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