Hardness distribution on wood surface

For better understanding wood hardness, we developed a new hand-operated ha rdness tester that works with Brinell's method. With this tester we investi gated the hardness distribution of wood minutely using a 2 mm diameter ball tip. The following results were obtained: (1) On preliminary examination w ith medium-density fiberboard, we found that the value of Brinell's hardnes s decreased with the increase in the tip ball's diameter but that it was al most constant with the indenting velocity. (2) By using a small diameter ti p, the difference of the hardness became clearer between earlywood and late wood. (3) With radial and tangential sections, we obtained hardness distrib ution patterns similar to those of wood grain. It seems that the hardness d istribution reflects the distribution of density on wood surfaces.