The effects of possible contamination on the radiocarbon dating of the Dead Sea Scrolls I: Castor oil

Some fragments of the Dead Sea Scroll manuscripts were contaminated with ca stor oil in the late 1950s. We have conducted experiments in order to estab lish if the AAA pretreatment cleaning procedures conducted on Dead Sea Scro ll manuscript samples in the last two dating series (Bonani et al. 1992; Ju ll et al. 1995) were effective in removing oil contamination. Our experimen ts show that not all oil contamination can be expected to have been removed by the acid-alkaline-acid (AAA) pretreatment, and that the radiocarbon age s previously reported therefore cannot be guaranteed to be correct. Any sam ples contaminated with castor oil were most likely reported with ages that are too young by an unknown amount.