Nanotechnologies for the conservation of waterlogged wood: the Vasa case studies

Conservation of waterlogged wood is a challenge in cultural heritage conservation. Samples, from the Swedish warship Vasa, have been investigated in order to formulate innovative methods for wood preservation. One of the causes of the Vasa wood degradation is the acidity that developed in the past years. Application of nanoparticles of earth-alkaline hydroxides neutralizes the acidity of wood and provides an alkaline reservoir inside, conferring a long-term protection to cellulose, as evidenced by hydrothermal aging of the de-acidified samples. Oak and pine samples from the Vasa wreck were characterized and treated with non-aqueous dispersions of Mg(OH)(2). Deacidification effects were monitored by pH changes and thermal analysis. Maximum pyrolysis temperatures of cellulose were analyzed in order to evaluate the degradation status of wood. The correlation between the temperature shifts of degraded cellulose respect to the non-aged cellulose and the corresponding polymerization degree variation were also investigated. Deacidification confirmed long term protection to wood.