Compression parallel to the grain deforms wood cells along their axis and failure occurs when cell walls start to suffer from instability. When the loads are applied perpendicular to grain, the cells deform easily due to the cavities in its interior. Once the cavities have collapsed wood becomes quite strong because voids no longer exist. Due to the high deformations caused by this mechanism of collapse, in practice, the strength perpendicular to grain is limited to 4% of its limit value.