Metal corrosion rates in aqueous treatments for waterlogged wood-metal composites

Corrosion rates are presented for metals in the aqueous solutions intended for treating both the wood and the metal components of a waterlogged wood-metal composite object. The metals include lead, mild steel, cast iron and the copper alloys of bronze, cast brass and wrought brass. The corrosion rates were determined using a standard weight-loss method in which clean metal surfaces were immersed in the solutions for two months at room temperature. The treatment solutions included Acrysol® G-11O for lead, Witcamine® RAD 1100 for copper alloys and Pluracol® 824 or the corrosion inhibitor Hostacor® KS 1 in PEG 400 for iron. These treatment solutions were prepared in distilled water as well as in a synthetic seawater. For reference, metal corrosion rates were also determined in distilled water, synthetic seawater and PEG 400. The results demonstrate that, in general, clean metal surfaces corrode more slowly in the treatment solutions than in PEG 400 solutions. However, before recommending these solutions for the treatment of composite objects, further testing is needed to determine how effective they are in reducing the corrosion rates of metals covered with a thick corrosion crust, and to see if Acrysol G-110 is capable of bulking and consolidating waterlogged wood.