Abstract
In Japanese traditional buildings, wood posts and lowermost horizontal beams are typically set on foundation stones. Surfaces of such posts and beams often develop whitish discoloration, spreading from the bottom side contacting the stones apparently where water becomes wicked. We conducted microscopic observations, whiteness measurement, and X-ray fluorescent, X-ray and X-ray diffraction analyses of the whitened wood surfaces obtained from four different buildings. Particles of several micrometers in diameter were observed on the surface of all specimens, and these particles densely covered the surface with high whiteness values. X-ray fluorescence and X-ray spectra of all the specimens showed strong peaks at energy ranges of the elements Ca, S, and O, especially surface whitening was conspicuous. Wood samples that had been kept indoors did not show these characteristics. X-ray diffraction spectra for samples from three buildings suggested that the white particles consist of CaSO4・2H2O.
