Impregnability of Grevillea robusta using the sap displacement method

Abstract

The utility of construction timber can be improved through low-cost treatment methods that reduce the cost of replacing structural timbers replacement and thus help to conserve forests. The sap displacement method is simple and easily applied in rural areas. A study was carried out toinvestigate the effectivenessofthis technique with Grevillea robusta with a view to promoting this non- durable Kenyan species. Specimens with and without bark were treated with a mixture of copper, chromium and arsenic in concentrations of 2, 4 and 6%. Retention was determined and compared with the recommended values. Retention and penetration of the preservatives increased significantly with increased concentrations. Retention in debarked specimens was significantly higher than in un-debarked specimens, but in both cases, retention was higher than the recommended FAO values for various uses. These results suggest that the sap displacement method can be used locally as an effective treatment for Grevillea robusta timber for end uses such as fencing poles.