TREATABILITY OF PLANTATION TIMBER SPECIES WITH CCA (COPPER·CHROME·ARSENATE) PRESERVATIVES AND THEIR EFFECTIVENESS AGAINST INSECT AND FUNGAL ArrACK

Abstract

This study was conducted to asscss the treatability of four plantation timber species (PiIlIlScariboca, 1/('\'('(/ brasiliensis, EII(,I1/I,/)IIIS gran.lis and EII('(/{y{)IIIS microcorvs) withCoppcr-Chromc-Arscn.uc (CC A) by using pressure impregnation full-cell process. Thetreatability of core wood and outer wood of the species were also investigated. Treatabilitywas evaluated by measuring the preservative retention (Net Dry Salt Rctcnt ion or NDSR)and dcpt h of pellet rat ion.

According to the results. Pinus I'IIl'ih(/(,1I showed the highest treatability while treatabilityof //C'I'I'(/ hrasilicnsis, Em (/{YfiIIlS grandis and EII('(/II'f'IIIS microcorvs were respectivelylower. A significant negative corrckuion was observed between density of the timber andtill' treatability. Rased on depth of penetration of preservatives. Pinus (,(/I'i/)II(,(/ and 1/('\'('(/brasiliensis were classified as permeable to preservative treatment. E. grandis was resistantwhile E. microtorvs was extremely resistant to preservative treatment.

Trc.unbilitv of outer wood of all the species were higher than that of core wood indicatingthe higher pcnncabiiity of outer S;IPWOOt! area compared with the inner core wood.

Trc;lting schedule with initial vacuum of -O.X bar. pressure of 6.5 bar maintained for IXOminutes ami final vacuum of -(),X bar was effective treatment of l l evcu hrasilicnsis. Evenwith this pressure. it was unable to achieve depth of penetration levels as specified in theSri Lankan Standards for E. grandis and E, IIIicro 1'01'\'.1'.

When wood samples were exposed to exterior ground contact in the grave yard test for fivemonths. none of the treated samples were infected, hut untreated control samples wereattacked hv fungi and termites. This indicates the effectiveness of the CCA treatment incontrolling fungal and insect attack.