IAEA-C4 is a sub fossil Waikato Kauri wood sample excavated from peat bogs in the north island of New Zealand, where the trees fell naturally some 40 to 50 thousand years ago and were preserved in deep peats. Some 70 kg of milled beams were prepared under guidance of W.G. Hogg and H.A. Polach, in cooperation by the University of Waikato, the Australian National University (ANU), and the New Zealand Paper Industry Research Centre. A homogeneous sample was prepared based on pulping at high steam pressure and temperature the wood chips derived from the beans. The wood chips - half pencil size slivers - were mixed, the resulting pulp was mixed, compressed into soft board, and dried.
During preparation, the mill was steam and water cleaned and the first 10 kg of pulp were discarded. The wet pulp being dark brown, a puff of white fibres appeared now and then. It originated from the dislodgment of previously milled Pinus Radiata. Staff picked out the clearly visible fibres and it is believed that the resulting sample, if prepared in 5g bulk, would be homogeneous and uncontaminated by modern carbon. The recommended value of this quality control material is the result of the statistical evaluation of an interlaboratory comparison [1, 2].
Reference date for decay correction: 1991-01-01
*) Marked value is the 95% confidence interval for the median, as reported in the respective literature 
ROZANSKI, K., Consultants' group meeting on 14C reference materials for radiocarbon laboratories. February 18-20, 1991, Vienna, Austria. Internal Report, IAEA, Vienna (1991).
ROZANSKI, K., STICHLER, W., GONFIANTINI, R., SCOTT, E. M., BEUKENS, R. P., KROMER, B., VAN DER PLICHT, J., The IAEA 14C Intercomparison exercise 1990, Radiocarbon, 34 3 (1992) 506-519.