Micromorphology of spruce timber after long-term service in a potash store house

Abstract

Sprucewood samples from construction timber in a 40 year old store house were examined for microstructural and chemical changes effected on the exposed surface. A degradation of the surface cells extending to a depth of only 5 mm was the most predominant feature, resulting in their separation. Analysis of the fine structure of the tracheids revealed a deposition of potassium chloride crystals leading to a pattern of degradation resembling alkaline cooking. All the wall components including lignin, cellulose and hemicelluloses of these disintegrated tracheids seem to become affected. Deeper in the wood (3 mm) the hemicelluloses are the main components that become hydrolyzed. The degradation is limited to the outermost surface layers of the timber event after such a long service life, so that repairs are not very extensive. In general sprucewood can be considered as highly resistant in such storage houses for mineral fertilizers