Lost Wax casting is an excellent way to produce complex sculptures and intricate surfaces. However, the cost of both the raw materials and labour of the operation makes it – compared to other procedures – quite an expensive process, especially with sculptures on the larger end of the size spectrum. Many of those gigantic ones are neatly cobbled up out of smaller, more unadorned surfaces and forms. Such a situation calls for an economical and efficient casting process: Sand casting or Sand-piece moulding. And most foundries will have equipment for both methods, though there are far more of only lost wax than the latter.
Eastern Mesopotamia, or the ‘Fertile Crescent’ circa 4000 BC, is the most likely origin point of this old tradition. Around 2575 BC, Egyptian metalworkers, through trade links, gained casting skills – both with sand and lost wax – and it was around 1450 BC that they used advanced techniques, according to archeology. Eventually, with significant influence, the Egyptians passed on their metal-casting knowledge to the Greeks, who by 600 BC adopted a simple bi-valve (two-part) sand piece moulding technique.
The Western historical record for using the lost wax method circa 1900-2000 AD is sketchy at best. Despite the many artful achievements from Italy during the Renaissance, most bronze items cast between the end of it and the ~2000s used sand casting. The former method remained static until the 20th century, and For example, it was not until 20th-century European immigration that this process developed majorly in the United States.
Judging from the point that lost wax was the predominant technique, it may have been strange for sand piece moulding to have made a comeback. However, many refined developments of the former were either uneconomical or unavailable until around the mid-20th century. The necessary combination of experience and capital led to a few who could form companies/foundries, a few that try to create a ‘cartel’, wherever and whenever possible.
Sand casting, meanwhile, had many an evolution, beginning in the Industrial Revolution of the 18th century because of a sky-rocketing interest and a buyer-base for good cheap designs and efficient materials and manufacturing methods.
We can now cast complex sculptures using sand with processed sands and efficient binders through modern developments, transferring intricate textures from maquettes into metal.
Most historical works of art that use the founding process use sand, and fewer of them use lost wax, and even fewer use it by itself. For bronze works, the sand cast, and infrequently straight fabrication, were used. Both techniques are more direct and demand fewer intermediate stages in production when compared with lost wax. Saving quite a bit on materials and labour.
To find an excellent example, we will head to the Todaiji temple of Japan and find the ‘Rochana’ statue constructed in 749 AD. Standing some 15 metres tall, with a 300-millimetre thick cast wall, and having a metal content of around 300 tons.
The first construction method used two techniques, fundamental for sand piece modelling – a sequential on location casting, enabled by temporary kilns close by the site. A refractory mould is built on-site, and the metal charge is tucked right into it from the said kiln or furnace. This process repeats ad infinitum until completion.
The second method involves a remote casting of the individual sections, which are then combined on location. In the example, flow welding was used. Such a technique’s structure can be supported through a ‘skin’ over the fabricated sub-frame, which coincidentally helps guide the subsequent few steps. Most if not all modern usages use similar on-location fabrications and installation methods.