DIMENSIONAL STABILITY PROFILE OF PRIMAVERA AND ROSA MORADA WOODS

Abstract

The profile of dimensional stability of Roseodendron donnell-smithii (Primavera) and Tabebuia rosea (Rosa morada) woods was determined by the experimental research of its major dimensional movement indexes and anisothropies, according to the DIN 52 184 regulation. Six trees for each species were collected at Chiapas state; from the normal diameter part of each tree, 24 25 x 25 x10 mm test specimens were made, which were moisture saturated and were conditioned sequentially in climate of air relative humidity of 65, 85, 35 and 0 % and water inmersion up to saturation in order to calculate several indexes. Results show radial swelling = 3.3 and 3.0 % and tangential = 6.2 and 6.9 %; radial differential swelling = 0.14 and 0.15 %/% and tangential = 0.24 y 0.29 %/%, normal radial shrinkage by drying = 1.3 y 0.88 % and tangential = 2.5 and 1.8 %; anisothropy of the differential swelling = 1.7 and 2.0, and anisothropy of the shrinkage by drying = 2.0 and 2.2. Based upon the latter, it is inferred that a stable behaviour might be had on the fase of changes in its moisture content, from the green condition to the dry one (MC≈12 %). Manufacturing with dry wood of thses species will show very good dimensional stability in the use of environments of air relative humidity of 65 to 85 % or 65 to 35 %. Except for the normal shrinkage from drying (greater in Primavera wood), the dimensional movement of both was similar in spite of the difference in density.