The adhesion properties of wood preserved with natural preservatives

Wood preservation technology has been using synthetic preservatives for a long time. However, some disadvantages have been recorded such as quality degradation of environment, killing more non target wood destroying organism. Since environment quality requirement has been up lifted, then general wood processing and wood preservation paradigm has to change from utilization of synthetic to natural wood preservatives. The new natural wood preservatives have their own properties and influence differently on wood adhesion. Wood adhesive based products such as plywood, lamination, particleboard and fiberboard use wood waste consisting of all kind of processes wood such as naturally preserved wood. The objective of this research is to know the effect of naturally wood preservatives on wood adhesion properties. This research was conducted by wood adhesion block method. The fast growing teak plantation wood was chosen since this type of teak wood was claimed as low grade of wood quality. This type of wood has high portion of sapwood which is susceptible to wood destroying organism. The source of natural, local wood preservatives are gadung tubers, pulai bark and kumis kucing leaves. The wood adhesive used was bio-industrial PVAc in the form of glue paste. Extraction procedure of natural wood preservatives followed ASTM D1110-1984. The procured naturally extracts was processed to obtain extract concentration 1.00 gram per liter concentration. Wood preservative application used padding method on the wood surface by 0; 1; 2 and 3 application times. Each padding layer processed was applied after the former one was air dried. Wood adhesion test followed block type with 40#/MSGL glue spread and cold press system. Compression shear test of block samples followed British Standard (1957). This adhesion test method was chosen since the method has proven as efficient and effective adhesion test in the laboratory. The research results showed that interaction factor of natural wood preservative and padding application did not affect to the adhesion strength. This adhesion strength was affected by single factor of natural wood preservative and padding application. The highest adhesion strength of 94.29 kg.cm-2 was resulted by pulai bark followed by gadung tubers (80.61 kg.cm-2 ) and kumis kucing leaves (55.31 kg.cm-2 ). Padding application exerted a negative correlation to adhesion strength. Higher padding application number of natural preservative on the wood surface, lower adhesion strength. The reduction of adhesion strength of 1; 2 and 3 padding application resulted 20; 42 and 66 % for gadung tubers. Pulai bark extract reduced 24; 30 and 57 % while kumis kucing leaves lowered 22; 37 and 75 % consecutively.