The treatability of three lesser-known timber species, namely,Kyenkyen (Antiaris africana), Esa (Celtis mildbraedii) and Otie (pycnanthus angolensis) was investigated using a commercial copper-chrome-arsenate (CCA) preservative and treatment by the vacuum-pressure method at varying pressure magnitude~ (6~0, 828, 966 or 1104 kPa) and treatment durations(0.5, 1, 2 and 4 hours). Net dry salt retentions and depths of penetration were determined, and a permeability assessment of the' different wood species was made.
Preservative penetration increased significantly with increase in pressure in all three species, while preservative retention increased with pressure and time in A. africana and C. mildbraedii. There was no discernible effect of time on lateral penetration. Preservative distribution pattern in the tissues for all three species was either patchy or mottled.
A. africana sapwood and heartwood are moderately resistant, to preservative treatment at a pressure of 1104 kPa for a period of one hour or more, or a pressure of 966 kPa for two hours or more. The sapwood and heartwood of P. angolensis and C. mildbraedii on the other hand, are resistant even if treated at 1104 kPa for 2 hours or more using CCA preservative.