Cold and Steam bending properties of some lesser-used species of Ghana

The cold and steam bending properties of six selected lesser- used timber species in Ghana have been studied with a view of providing technical data for the furniture and glulam industries. Differences between timber species and thickness of bending lamella have been found to be statistically significant in cold bending of the six species (P= 0.05). Cylicodiscus gabunensis has been found to have superior cold bending qualities for all the thickness studied, followed by Petersianthus macrocarpus, Ceiba pentandra, Albizia ferruginea and Antiaris toxicaria in that order of decreasing performance.

Although in 9mm thickness, Celtis milbraedii is next to Cylicodiscus gabunensis, its performance in 12 and 25mm is very low. Thickness factors derived indicate that thickness effect is severe in all the species, with Celtis and Ceiba showing the most severe effects. High density species also seem superior in cold bending properties to low density species. For steam bending, however, Celtis has best qualities followed by Antiaris, Albizia, Cylicodiscus,Petersianthus and Ceiba in decreasing order.

Whereas Ceiba's weakness under steam bending may be attributed to its brittle wood fibres and high porosity, Celtis's superior quality may be due to its fine texture, low porosity and straight grains. Density does not seem to influence steam bending qualities for the six species. Apart from Antiaris and Albizia, all the species studied may be recommended for cold bending, and only Celtis for steam bending in the furniture and glulam industries.