Obtaining the adhesion rate of the extender pigments on the wood surface and the packed condition of the flat particles contained within the extender pigments in the vessel model, the following results were concluded. 1) After the filling treatment on the extender pigments No.2, 11, 13 and 15, the adhesion rate increased under pressure and on the Y. S., the K. S. series (No.2 and No. 15 with silica added) and the Y. Y. series, (similar extender pigments No.13 and No.2 mixed) the rate of increase of the adhesion rate is great under pressure. 2) Observing the packed structure of the extender pigments, the flat particles in the extender pigments of unstressed condition have an -86.5° average inclination to the standard axis (press direction), and the magnitude of orientation is small (24%). In comparison to this, at 10 kg/cm2 the average inclination is -66°, the magnitude of orientation is 55.8% and at 15 kg/cm2 the average inclination is -71°, the magnitude of orientation is 61.6%. The flat particles orient under pressure in the perpendicular direction to the press direction.
The obtained clay characteristic of Y. S., K. S. series which was added silica on extender pigments and the relaxation effect to the strain on wood surface by the strain sensitive method were proved. 1) The plasticity of the Y. S. and the K. S. series decreased with addition of silica. The plasticity of the Y. Y. series aid not change. 2) The drying shrinkage rate of the Y. S. and the K. S. series decreased with addition of silica. 3) On all kinds of woods the relaxation effect of strain on the wood surface increased by the addition of silica. In the Y. Y. series, which was a mixture of like extender pigments, the increase of the relaxation effect was not recognized. The relaxation effect by the filling treatment was affected considerably by the filling quantity.
The following results were obtained for wooden base with extender pigments and cloth. 1) After each added layer of the Y. S. and K. S. series mixed at random ratios to wooden bases of various tree species the strain on the specimens decreased and the relaxation effect was gained. In the Y. Y. series tests, by using random ratios and various tree species no clear results could be obtained. 2) Flat irregular shaped particles of quartz orientate easily with the flat kaolinite particles inside the pigment layer in the Y. S. series, but in the K. S. series, the quartz particles do not easily orientate with the pillar shaped halloysite particles inside the pigment layer. 3) Layer of filling pigments and outside layer of extender pigments greatly act on the relaxation effect of the original strain on the wood, but when layer of padding cloth is used it is regarded as a setting surface and there is no effect on the original strain of the wood.