Armagh Miniature Street Art

Applying Ancient Technology

The technology that was used to cast the twenty two gargoyles and angels has been around in Ireland since the Late Bronze Age: the lost wax process in combination with clay moulds. Appropriately, they were cast only two miles away from Mount Gabriel where some of the oldest copper mines of North-West Europe are located. But it is not only the archaeological aspect which interests Holger. Using local materials, sustainably produced charcoal and recycled bronze makes the process itself carbon neutral, offering sculptors an environmentally sustainable, inexpensive and low-tech approach to producing permanent artwork.

Owing to the high durability factor of bronze and its long lifetime, these sculptures for Armagh contain very low embodied energy. 100% recycled bronze has been used in producing the work together with moulds that were made from abundant locally sourced materials. An average of 80% of all waste materials were recycled and re-used again in the process. This kept the total embodied energy input in the actual production process as low as 6,500MJ. Spread over 22 sculptures, this is an average 295MJ of embodied energy (EE) per item. The project produced a total of 800kg of CO2 emissions, the majority of which accounted for road transport and LPG fuel.

Full Environmental Impact Assessment (212MB pdf)  |  Hide adverts on top: Ads off!

The Lost Wax Process

From Transient to Permanent Form

More than a dozen stages were involved to create the gargoyles and angelsfrom beginning to end. Each stage requires considered decisions and attention to detail to achieve a good end result. And in each stage problems have to be resolved. Although complex and full of chemistry and physics, metal casting has been practiced nearly unchanged for more than 4,000 years in Ireland.

There is reliable evidence of the lost wax process in Ireland dating back to the Iron Age. The technique gives the sculptor more creative freedom than any other casting technique. The sculptures are first modelled in clay from which a silicon rubber mould is taken. From this, a pattern of the work is reproduced in wax, today a mix of beeswax, synthetic waxes and resins. After adding a runner and riser system, the work can be degreased and moulded. Various molding techniques are available to the sculptor but for the gargoyles and angels an ancient mix of sand, clay and dung was employed. The mould material was applied by dipping in a slip of these materials. The moulds were dried in the sun between consecutive dips, which only in bad weather was accelerated by using a drying cabinet. A mould thickness of 15-20 mm is sufficient after which the wax is melted out, first by blowtorch then in a kiln below 200ºC. Setting the moulds on a water-filled baking tray with a drying rack or grid will help to retrieve up to 75% of the wax. The mould needs to be fired after melting out. Bisque firing to 600ºC for three to four hours is sufficient. A self-built flat-pack kiln was used for both these processes. The moulds were then wrapped in clay covered hessian and poured cold.

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