Determination of Swelling and Dimensional Stability of Some Nigerian Timber Species

Abstract

Aim: The absorption of moisture and dimensional distortion are the major shortcomings of wood utilization as building and furniture materials. This study was aimed at determining the moisture content, swelling ability and dimension stability of five selected timber species. Methods: The samples were collected with the help of the Forest Ranger from the Forestry Department of Enugu State, Nigeria, attached to the Nsukka timber market. The wood samples were evaluated for moisture content change, shrinkage or swelling (%) coefficient, amount of swelling and dimensional change. Results: The change in moisture content across the five species was in the order of Gmelina aborea < Milicia excels < Daniellia oliveri < Alstonia bonnie < Antiaris toxicaria. At 12hrs, Gmelina aborea recorded significantly (P < 0.05) the highest dimension change (46 ± 0.70%) in the radial dimension (direction) as compared to the other species except for Antiaris toxicaria. The swelling coefficient and the amount of swelling were observed to have a strong positive correlation with the dimensional change in the sampled wood. Conclusion: The lower swelling coefficient and the amount of swelling observed in Milicia excels among the five timber species, make it a more suitable species for industrial use.