Steam bending qualities of eight timber species of Ghana

Abstract

Steam bending qualities of eight lesser used timber species of Ghana have been studied and compared with the quality of Mahogany (Khaya spp), a fast diminishing noble species, with the view to providing information for the furniture and glulam industries. Wood samples collected from three ecological forest zones of Ghana were steamed in an improvised steam chamber and bent on a prepared jig to a curvature of 660mm. Danta (Nesogordonia papaverifer­a) was identified to have the best steam bending quality followed by Yorke (Broussonetia papyrifera), Rubberwood (Hevea brasiliensis), Cedrela (Cedrela odorata), Eucalyptus (Eucalyptus tereticornis), Emire (Terminalia ivorensis), Cocowood (Cocos nucifera) and Borassus palm (Borassus aethiopum) in that order. The good steam bending performance of Danta and Yorke was attributed to their straight wood grains and fine-texture, and the poor steam bending qualities of Cocowood and Borassus palm was attributed to their fibrous wood grains, and the interlocked grains of Borassus palm. Yorke and Cedrela had good steam bending qualities despite their brittle wood fibres and their low porosity. There was no clear relationship between wood density and steam bending qualities of the eight species. Wood density however seems to affect the ease of bending the wood after steaming. Due to Mahogany’s superior steam bending qualities, it was placed in a proposed quality Class I category with excellent steam bending quality, whilst Danta, Yorke, Rubberwood, Cedrela and Eucalyptus were placed in Class II category with good steam bending qualities. Emire, Cocowood and Borassus Palm were, however, placed in Class III category with poor steam bending qualities. Danta, Yorke, Rubberwood, Cedrela and Eucalyptus may be recommended for steam bending in the furniture and glulam industries.