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From evidences to facts: the Iberian ironworking chain under an experimental perspective at the Iberian Citadel of Calafell

Date: 
Saturday, 5 April, 2014 to Saturday, 26 April, 2014
Responsible: 
José Miguel Gallego (Artíifex,crpa)
Josep Pou (Ciutadella Ibèrica de Calafell)
Manel Gómez (Ciutadella Ibèrica de Calafell)
Ibercalafell (associated partner)
Number of Participants / Visitors / Audience: 
1400

In November 2013, the technical staff at the Iberian Citadel took the decision to develop an experiment regarding iron working. After some meetings with researcher José Miguel Gallego who had made previous iron bloomery furnaces, we could finally have a proposal to be discussed in the Scientific Committee of the Iberian Citadel composed by professors of the University of Barcelona and the Catalan Institute of Classic Archaeology (ICAC)both associated partners of OpenArch.

The proposal aimed to recreate the whole iron working chain of the Iberians to obtain iron in order to make artifacts as it was archaeologically documented in the site of Les Guàrdies, in the town of El Vendrell a few kilometres away from Calafell. Les Guàrdies is an exceptional case in the Iberian world as it is the only site in the Iberian context where we can find evidences of the integral workchain.

The first step was to build a charcoal kiln to obtain around 200 ks of charcoal from olive and ilex trees (3000 kgs of wood used). Saulo Pujolàs and his father Pere, from Cànovas (a Catalan town with tradition of charcoal kilns construction) they were the experts who during 4 days worked to obtain charcoal. The charcoal kiln construction attracted many visitors to the Citadel who wanted to see this traditional way to obtain charcoal in rural areas.

Concurrently, first tests of the local clays with iron ore seams were made in order to check the ore proportion to ensure we would have enough material for the furnaces. Basically, the processes to be followed were the extraction of the ore (open air mining), washing the clays, selection and roasting of the iron ore so that the optimum pieces of ore could be used for the furnaces.

Two furnaces were built in the experimental area outside the Citadel, according to the archaeological evidences found at Les Guàrdies. One of the hypothesis we aimed to work was that the Iberians of Les Guàrdies could use free-breathing furnaces in order to optimise the production (less workforce, more worthwhile system) instead of assisted breathing furnaces.

The big furnace (ELBUITE, 2m height) was feed with a tuyeres system in the windows and the outside air breathed the furnace through the tuyeres with the chimney effect as a result. This furnace was active during 82 hours non-stop. As for the small one, (ELNOBE, 1,30m) a hybrid system (free-breathing/induction)was used and it was active during 26 hours.

The main results were: high quantity of non-altered or half-melted ore, low quantity of bloomery stuff, inlays melt on the tuyeres, low thermal alteration of the internal walls of the furnace, very small iron blooms, impossible to compact by hammer (ELBUITE), high quantity of slags (ELNOBE). Natxo Fuertes helped with the post-reduction processes and forge works.

Samples of the experimental material such slags will be analysed by EMB/EDX at the Politechnical University of Catalonia.

This experiment is also linked to the Dialogue with Visitors as it has provided a lot of valuable hands-on and theoretical information to the educational staff about the ironworking processes of the Iberians of the Cossetan area which had an important influence of the Centro-European Iron Age culture (La Tène) besides the Mediterranean influences (Phoenician world mainly). The information then helps to improve the quality of storytelling when approaching the technology of the ironworking processes.

This experimental action made in the framework of OpenArch has been presented in the 4th International Congress of Experimental Archaeology (Burgos, Spain, May 2014) and the 7th OpenArch Conference (Kierikki, Finland, June 2014). It will also be presented at the Terra Ibèrica Festival in Calafell in July 2014.

Images

Charcoal kiln