Plaster vs. Clay Moulds II

It appears there were both drawbacks and benefits to working with these materials. Clay moulds were labour intensive and more susceptible to physical alterations during the firing process, yet they were extremely durable.  Plaster, by contrast, could form near-replicas of the original patrix in less than half the time.  However, they deteriorated at a faster rate, losing much of their detail with repeated use, and therefore required frequent replacement. The remains of ancient plaster moulds are often difficult to find, as it is a perishable material.  Fired clay stood a better chance at survival beneath the strata.  Yet, despite the numbers of clay moulds recovered, to judge from the surface of ancient lamps, plaster was preferred to clay.