Plaster is an ancient artifact and its manufacturing technology has changed over time. When lining an installation, plaster acts as a sponge, absorbing chemical elements from liquids and solids therein, thus acquiring a chemical signature in addition to that imposed by the plaster components. Chemical analyses may thus reveal an unusual (e.g. anthropogenic) signature which can be of use to the archaeologist. The petrography, chemistry and isotopic composition of plasters from major sites in Israel have been studied, the data provide the early building blocks of what should evolve as a significant plaster chemical data base. Qumran plasters were applied from one to four layers and are made of local materials. The manufacturing technology of all the layers is typical of the 2nd Temple Period. Chemical data were plotted on bimodal plots and compared with data from other ancient sites. The most revealing are the Al-Fe, Al-total metals, Zn-Cd, As-Cd, SO3-As and SO3-Mg plots. The most important conclusions drawn are: (1) the notable impoverishment of heavy metals in Qumran plasters points to a non-industrial and non-military community, (2) cadmium concentrations are anomalous and since Cd is a toxic element, high concentration in some installations may be significant with respect to Qumran life (and death) style, and (3) plaster in several loci contain high concentrations of salts and sulfates, which suggests that those specific pools were not cisterns or ritual baths, at least during the latter part of their functional history.