The (in)visibility of lost wax casting moulds in the archaeological record. Observations from an archaeological experiment

Apart from mould and core remnants attached to metal objects from the Chalcolithic Southern Levant (ca. 4500–3800 BCE), production remains of early lost wax casting are seemingly invisible in the archaeological record. An experiment using reproduced casting moulds was performed to simulate the Chalcolithic processes to investigate whether the moulds might have deteriorated to an unrecognisable state after the casting process. Results from previous studies on mould remains attached to metal objects were complemented with ethnographical accounts for the experimental set-up. The moulds were prepared from local clays already in use during the Chalcolithic. Petrography, simple alteration tests, and general technological considerations reveal that preservation may be poor but is still visible to the naked eye. The preservation of multi-layered fragments is crucial, despite their friable or brittle state after casting. A further, previously unmentioned, clear indication of lost wax casting moulds may be the combination of vegetal temper with mineral/rock temper in their clay paste. This composition derives purely from technological considerations and is independent of depositional and post-depositional processes.