Efficient processing and utilization of coconut trunks are aimed at solving technical and socio-economic problems especially when the coconut farmer decides to replant his senile palms. Being a monocotyledonous plant, its anatomical, physical, chemical and mechanical properties are different from the conventional woods. Hence, processing techniques and equipment including appropriate machinery have been developed, modified and improved to process cocowood more efficiently and produce comparatively good quality products.
The technology required for harvesting or logging coconut stems is almost the same as in traditional forest trees. However, the conveniently straight and branchless stems, and their nearly uniform volume and dimension allow the use of comparatively light and simple tools and transportation equipment. Logging operation in a coconut plantation is therefore easier and cheaper than logging under forestry conditions especially in mountains with steep terrain.
In sawing coconut logs, the most important factors in selecting the milling equipment are profitability and ability to be relocated if this is required; simplicity of design to avoid breakdowns which are difficult to repair in isolated situations; ease of operation as skills of operators will often be limited; an inexpensiveness as the industry is often situated in poorer and underdeveloped areas.
Different type of mills have been tested at the Zamboanga Research Centre in the Philippines and the Timber Industry Training Centre in New Zealand and information gathered could provide a guide to the selection of mills for different conditions. These mills include the medium-size portable sawmill, a larger transportable sawmill, light/general purpose portable sawmill, a mini mill, a breast bench with light weight carriages and a chainsaw with guide attachments.
Problems of sawing coconut logs are similar to the ones encountered by sawmillers when using high density species of tropical hardwoods.
It has been established that no importer is prepared to make a commitment to purchase large volumes of coconut wood unless both quality of material and reliability of supply are guaranteed. Uniform grading standards for coconut wood are therefore highly desirable. A system of grading coconut wood and the mechanics of its implementation and control should be established in the producing countries. The mechanism for quality control should not restrict efficient management but should aim to protect and rosier the interests of the country, the coconut wood industry, and its customers.
Quality control of coconut wood starts during the logging operation. Coconut wood should be graded hard, intermediate or soft, corresponding to high, medium and low density: high density is above 600 kg/m3; medium density between 400 and 600 kg/m3; and low density less than 400 kg/m3. Because of the widely varying density of material within each log, and the difficulty of differentiating these by superficial inspection after sawing, it is essential that a grading, sorting and identification system be established to track the wood from different parts of a log and from different logs along the length of a tree; this should start in the plantation at the time of felling. Systems of this sort have been designed and are implementable.
Another important phase in cocowood utilization is machining or the process of cutting and milling the cocowood into various shapes and patterns with the use of woodworking machines.
Seasoning and Drying
Coconut wood must also undergo seasoning process to minimize if not completely avoid problems in its utilization: the appropriate moisture content levels of coconut wood for various uses are as follows: furniture - 10 to 12%; flooring - 11 to 17%; framing timber -15 to 18%; joinery - 12 to 16%; and weatherboards - 15 to 18%. The common drying methods include air drying wood under shed, forced-air, and kiln drying. Depending on existing conditions, 25mm and 50mm coconut boards take 4 to 11 weeks and 16 to 21 weeks to air dry, respectively to attain equilibrium moisture content of 17% to 19%. Drying schedules have been worked out (Tables 8 and 9) for kiln drying coconut wood to avoid drying defects such as collapse, twist, wrap and check.
Coconut is not naturally durable when used in situations favourable to attack by decay fungi and wood boring insects particularly in ground contact and exposed to the weather. The low natural durability can be overcome by the application of suitable wood preservative treatment, for which appropriate prescriptions and dose rates have been developed. Choice of treatment depends on hazard level and cost which can be borne.
The recommended treating processes are presented in Table 10. The treatment schedules of the different processes have been established for coconut wood through a series of laboratory experiments, field and service tests of treated materials.
Good quality finish for cocowood involves sanding the surface to remove the knife marks and produce a smooth surface. The use of mechanical sanders instead of manual sanding facilitates finishing the surface of the wood.
Coating involves the sequence application of stain, filler, sealer and top coating materials such as lacquer, polyurethane, polyester and oil finish to enhance the natural beauty of the grain, colour and figure of cocowood products. Usually two or more coats of finishes are applied to cocowood to improve the appearance and quality of the wood products.