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title(En) :Surface Checking of Plywoods. II. Effects of Pressing Condition and Thickness of Veneers for the Surface Checking of Plywoods
author(En) :Yoshiyasu Yamagishi, Mikio Okada
information :Mokuzai Gakkaishi 6(4), 152-157 (1960)
assort :Original Article
summary(En) :   Continuously since publication of the previous report, effects of the pressing condition, the thickness of the veneers, an assembly method of them and quality of the core veneers for the surface checking of plywoods have been investigated by utilizing the weather meter. Species of the veneer are Shina (Tilia japonica SIMK.) and Sen (Kalopanax septemlobus SOIDZ.) and quality of the veneers used in this experiment and surface appearance of the plywoods after the weather meter test are shown in Table 1, Fig.1 and Fig. 2.
   The results obtained are as follows:
   (1) In accordance with diminution of thickness, the difference of the surface checking in the case of exposing a tight side of the face veneer and in the case of exposing a loose side will be scarcely recognized, the reason being that the thinner the veneer, the less the difference of the surface qualities between a tight side and a loose side.
   (2) In the case of using 0.4mm or 0.2mm face veneers, the wavy undulations perpendicular to the grain of the face veneer have been recognized on them by means of the core veneer quality especially in the latter veneer (0.2mm), and sometimes these undulations cause the surface checks to occur and moreover, the dulamination of the face veneer, the reason being that the thinner veneer cannot overcome the stress of shrinking and swelling or the influence of the surface irregularity of the core veneers. In the case of 0.75mm or 1.0mm veneers, no appreciable difference could be recognized as in the case of 1.36mm veneer in the previous report.
   (3) Sen veneer is noticeably apt to grow surface checks and is sensitive to the pressing condition owing to the presence of large vessels and the irregular shrinkage of the part surrounding them. Generally, as regards the surface checking, the effects of the pressing condition is not more dominant than that of thickness of veneer, the assembly method, and quality of the core veneers.