PRESERVATIVE TREATMENT OF JAK (Artocarpus heterophyllus) SAPWOOD USING CCA AND BORON PRESERVATIVES

Abstract

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InSriLankaJak timber is listed as a special class timber. Jak timber has high demand for the construction and furniture. Jak heartwood is highly durable. However, sapwood is susceptibleto borer attack. Jak sapwood can be used if proper treatments and finishings are given.This study was conducted to determine the most suitable and practical treatment method for Jak sapwood to improve its durability. 10 trees of Jak (Artocarpus heterophyllus) were selected for this study. Sapwood samples and heartwood control sampleswere extracted from each tree. Jak sapwood was treated by three methods: Boron (Cold) diffusion and Boron (Hot & Cold)open tank method using 25% boron solution and Pressure Impregnation Full-cell processusing 2.8% CCA solution. The treatability of different age trees were evaluated by measuringthe preservative retention and depth of penetration. Effectiveness of the treatmentwas evaluated by percentage weight loss in field exposure test. Accordingto the results, retention in CCA pressure treated samples was higher compared with boron diffusion methods. Boron (Hot & Cold) open tank method gave higher retentioncompared with boron (Cold) method. There was no relation observed between preservativeretention and percentage weight loss in field exposure test. Spot test showed full depthof penetration (100%) in both boron treatments and 46% of penetration in CCA pressureprocess. Afterthe field exposure test, the highest weight loss was recorded for boron (Hot & Cold) treatedsamples and second weight loss was recorded in boron (Cold) treated samples. Therewasno significant difference of the penetration and weight loss between two boron treatmentmethods. Weight loss of the eCA pressure treated samples was very small. Althoughthe full depth of penetration was not achieved the CCA pressure impregnation scheduleand solution were more effective fur the preservation of Jak sapwood. Basedon results, it is clear that Jak sapwood can be fully treated with boron diffusion methods and effectively treated with CCA pressure impregnation method. Diffusion methodsusing boron solution is recommended for the interior joinery and CCA pressure impregnationis recommended to use Jak sapwood in exterior construction activity. However,sapwood of Jak showed other undesirable characters in terms of utilization: comparedwith heartwood, density of sapwood was low, and shrinkage was higher.