Treatment of Selected Lesser Used Timber Species against Subterranean Termites using Heartwood Extracts from Teak (Tectona grandis) and Dahoma (Piptadeniastrum africanum)

IRG/WP 08-30476

A Asamoah, C Antwi-Boasiako, K Frimpong-Mensah

Lesser used timber species represent a valuable material for all-purpose uses. However, most of them are not durable. They are, for effective utilization, often treated with all manner of toxic synthetic substances to enhance their natural durability, especially in the tropics where conditions favour their deterioration. Most of these toxic synthetic substances often pose a threat to the environment. Currently, one probable measure is to treat low durability timbers with extracts from highly durable ones. Heartwood water extracts of Teak (Tectona grandis) and Dahoma (Piptadeniastrum africanum) were impregnated into ten Ghanaian LUTS and exposed in the field to the ground for 8 months in accordance with European Norm 252. Visual durability ratings, hardness and mass losses were measured in assessing their field performance. Teak extract did less harm or conferred better resistance on LUTS in more instances than Dahoma extract did. The enhanced durability of LUTS was ranked as follows: Albizia ferruginea > Pertersianthus macrocarpus > Blighia sapida > Sterculia rhinopetala > Amphimas pterocarpoides > Cola gigantean > Celtis zenkeri > Sterculia oblonga > Antiaris Toxicaria > Canarium schweinfurthii. Though extracts showed reduced efficacy with time, indications were that extracts from the heartwood of tropical timber species as that of Teak could be employed to preserve their low durability counterparts. Attempts at fixing extracts permanently in timber should be made. The use of natural organic preservatives is promising if it will be deeply researched.


Keywords: deterioration, resistance, Teak, Dahoma, mass loss, hardness loss, durability rating

Conference: 08-05-25/29, Istanbul, Turkey


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