Archaeological wood can only survive in anaerobic wet or very dry conditions. If waterlogged wood is allowed to dry out, surface tension forces cause the wood to collapse and the artefact to crumble. Traditionally impregnation with polymers followed by air or freeze drying has been used to conserve such artefacts but this is a very slow process (months) and the polymers used enhance iron corrosion meaning that composite artefacts cannot be conserved. We have introduced "Super critical drying" of the wooden artefacts. The water in the artefact is first replaced with methanol and the methanol is then extracted with supercritical CO2. Excellent results are obtained in terms of dimensional stability and the process can be completed in a few days rather than several months. It is compatible with iron and we have successfully conserved composite artefacts consisting of wood, iron, cloth and copper. A rapier handled conserved using the technique is shown in Figure 1.

Figure 1
Figure 1. Rapier handle from The Swan

Ruben Duque 2011. All rights reserved