Making furniture from eucalyptus wood
EUCALYPTUS wood is a perfect contortionist -- when sawn, it can crack, bend, warp and twist. Making furniture out of this wood, therefore, has been a hopeless task. But now scientists at the Dehra Dun-based Forest Research Institute have developed a way of seasoning and sawing eucalyptus so that it doesn't crack.
Normally, a log is sawn lengthwise into planks. But sawn this way, eucalyptus develops cracks. This is because of the peculiar distribution of stresses in the wood; the outer fibres are stretched and the inner ones are compressed. So any longitudinal cut upsets this balance and the wood cracks.
Eucalyptus wood also starts cracking if it is not seasoned soon after the tree is felled. "This tree has a lot of moisture in it, which if allowes toescape quickly, can give rise to cracks", explains R N Pandey of the institute's wood seasoning branch. So the ends of felled logs are smeared with bitumen to let them dry slowly.
"Faced with this problem, we didn't know what to do. So we chose the shotgun approach -- cutting the logs in different ways hoping one of them might click," says R N Pandey of the institute's wood seasoning branch. The approach succeeded. The researchers found seasoned logs when sawn radially showed no signs of cracking (See diagram).
The FRI findings are being used to manufacture furniture at the workshops of the Punjab State Forest Development Corp in Phillaur and Patiala. A chair made of eucalyptus wood costs half as much as one made of teak.
Despite FRI's efforts, the few private furniture-makers who have experimented with this wood are eager to wash their hands off it. Says Ajay Gupta of Chandigarh-based Glass Palace, "We have made eucalyptus furniture for some time now, but there are too many complaints of warping and twisting. We have decided to abandon it." So have other furniture makers.
Says Avatar Singh, project officer at the Phillaur workshop, "With the best of precautions, the risk of cracks cannot be ruled out."
Nor is radial sawing economical for logs less than one metre in girth. Says Gupta, "As much as 20-25 per cent of wood is wasted by this method. Also, it takes about 25 years for a tree to grow to this size and most private growers do not wait that long to fell it."