This work is a comparative study of iron smelting practices among the Pangwa and Fipa peoples of Tanzania. The author discusses local concepts of metallurgy by step-by-step observations of the processes involved. Included is a description of the technology observed in several re-enactments of smelting practices and a discussion within a comparative framework of the multiple and shared levels of meaning and experience (symbolic repertoires and symbolic reservoirs) held by technicians during these observedtechnological processes. The study demonstrates, with a focus on magic and metaphors, the link between perceptions of the body and concepts of the technology. The author shows how a shift in the concepts of the technology is also useful for those studiesof iron technology where there are no living exponents to answer questions about the use, or meaning, of specific objects or processes.