DECAY PREVENTION IN WATERLOGGED ARCHAEOLOGICAL WOOD USING GAMMA-IRRADIATION

Gamma irradiation is evaluated as a novel decay prevention treatment f or waterlogged archaeological wood. A dose of 15 kGy was found to be s ufficient to inactivate a large number of wood biodeteriogens, includi ng fungi, bacteria and invertebrates, at various stages of development . For timbers excavated from polluted sites, a dose of 25 kGy is sugge sted to inactivate human pathogens. The dose spread required for such treatments are 1.33:1 and 1.2:1, respectively, in timbers up to 150 mm thickness and density not exceeding 1590 kg/m3. No adverse effects on the physical properties of slightly or heavily degraded waterlogged a rchaeological wood were detected at doses of up to 100 kGy. This is th e maximum recommended single or cumulative lifetime dose for any timbe r. Gamma irradiation offers far greater efficacy over currently used d ecay prevention treatments and, a step-wise procedure for evaluating t imbers for treatment and dosimetry is presented. (C) 1998 Elsevier Sci ence Ltd. All rights reserved.