Furniture making was perhaps one of the earliest modes of utilizing forest resoures, especially timbers, and wooden furniture will be with us for a long time, mainly due to its many desirable characteristics. No other material is like wood, which as it grows old in service has its beauty enhanced. Wood can be easily shaped by had or machine tools, be fabricated into a wide range of sizes by adhesives, dowels, nails or screws. Ancient craftsmen used to boast of gigantic structures completely built of wood without any metal fasteners. Moreover, damaged parts or components can be easily repaired or replace.
Furniture made in Malaysia can be broadly classified into the following groups: A. Heavy duty furniture
This category includes work benches, laboratory benches, laboratory and shop shelves, kitchen benches and tables, garden or out-door sets. The main criteria are sturdiness, good resistance to scratching and long service life.
B. General utility furniture
This group consists of normal household furniture, school desk and chairs, office furniture, chairs for convention hall/community centres. The major concern is price, but other criteria such as reasonably long service life and weight are also important.
C. Decorative furniture
This is a specialised group which includes high class office, household, hotel and resturant furniture. The main emphasis is colour and appearance.
Desired Properties
Generally, furniture require timber with sufficient strength, good machining properties, good dimensional stability and reasonable durability. Other properties such asdensity, nailing and gluing properties, colour, grain patterns and texture are also important factors.
Sufficient Strength
Most furniture are only subjected to equally distributed load rather thean concentrated load, and usually a large portion of this load is taken up by the joints. Thus timbers for making furniture need not be very strong. Moreover, stronger timbers usually mean heavier timbers and hence heavier furniture. Therefore, except for special function, heavy duty furniture are normally undesireable. As a rule of thumb, timbers of Strength Group C and above, with densities of about 500 kg/cu.m are generally suitable for making furniture.
Good Machining Properties
Good machining properties are required to produce good quality furniture. Thus, timbers for furniture should ideally be easy to plane, saw, turn or bore, and the surfaces produced by these processes must be smooth without any tearing of fibres. Although ease of machining and surface quality can be improved by using tungsten-carbide tipped tools and extensive sanding, these will invariably incur extra costs. Timber with too much extractives such as silica will cause rapid blunting of cutting tools. The presence of resins in some Malaysian timbers may clog up saw teeth and abraisive papers. All these will result in extra tooling cost and excessive machine down time.
In practice, it is difficult to find all these desirable characteristics in a single species Moreover, many timbers that have many other good properties may not machine well.
Good Dimensional Stability
Timber changes in dimension when the moisture content in the wood is varied. Excessive dimensional changes will cause distortions in furniture components and perhaps, the whole piece subsequently. Jamming of drawers and doors, opening up of joints and even complete breaddown of furniture during service are common examples Particular attention must be paid when using wooden furniture in air-conditioned rooms where ambient changes are drastic and the resultant dimensional movement of the timber may cause problems.
Timbers of inherently low shrinkages are thus ideal for furniture making. Furthermore, boards shuld be quarter sawn, as quarter sawn board will shrink less. Additional precautions, such as applying coasts of varnishes or paints on all exposed surfaces will reduce moisture uptake during service, thus minimizing dimensional changes.
Reasonable Durability And Treatability
As a general rule, denser timbers are more durable than lighter timbers. However, the durability of the lighter and less durable timbers can be improved by preservative treatment. Proper preservative treatment will protect the wood against insects and fungal attacks before manufacturing and also during subsequent service. However, the right type of preservatives must be used in order to avoid damaging the appearance of the timber. Other Desired Properties
Furniture parts are fastened by several means. Common fasteners such as bolts, nails screws, dowels and glues, or combinations of these are popuraly used. As such timbers for furnitures making should have good nailing, boring (for boths and dowels) and gluing properties.
End-Use Criteria
The suitability criteria, encompassing the desired properties mentioned above, are as follows:
A. Heavy duty furniture
Strength:
Durability:
Strenghth Group B and above, i.e.,
* Compression parallel to grain > 14.0 N/mm2
* Compression perpendicular to grain > 1.0 N/mm2
* Bending tension parallel to grain > 17.0 N/mm2
* Shear parallel to grain > 2.0 N/mm2
Durable or easy to be treated with preservatives.
B. General utility furniture
Strength:
Workability:
Glueability:
Durability:
Strength Group C and above, i.e, * Compression parallel to grain > 10.0 N/mm2 * Compression perpendicular to grain > 0.7 N/mm2 * Bending tension parallel to grain > 12.0 N/mm2 * Shear parallel to grain > 1.4 N/mm2
Easy to slightly difficult
Satisfactory
Moderately durable or easy to be treated with preservatives.
C.Decorative furniture
Timbers for decorative furniture must possess all the properties as listed under general utility furniture timbers, in addition to having pleasing figures, grain and colour.
However, some timbers, which have pleasant figures, grains or colour, are rather weak and also not durable. Thus, when using such timbers, it is preferable to treat them with preservatives to extend their service life. In most case, beauty of the wood becomes the prime consideration.
Consumer taste changes and advances in related technologies may make many timbers, previously considered undesirable for furniture-making, gaining acceptance by the industry. For example, while dark-coloured wood such as Sepetir, was the preferred species at one time, the trend during the eighties seems to prefer lighter coloured or whitish wood such as Rubberwood, Ramin, Mempisang and Kembang Semangkok. Furthermore, staining has grown in popularity, and staining could remove any imperfection in colour uniformity considerably.
Hardwood
The term hardwood designates to all leaf-bearing or broad teaved trees and enclosed nuts or seeds. Hardwood is of higher density of hardness than softwood and they often grow in subtropical region like Asia and Africa and in some regions in Europe. The most often used in furniture include teak, cengai (neobalancarpus heimii), oak rosewood, walnut, cherry, birch and mahogany, nyatoh, merban, rengas, resak etc.
Softwood
Tree or wood from conifers (needle bearing trees) or foliage that remains green all year around. These include pine, sprace, cedav, fir, lardh, hemlock, redwood, kembang semangkok, geroggang, ramin, rubberwood, jelutong etc.
Furniture making was perhaps one of the earliest modes of utilizing forest resoures, especially timbers, and wooden furniture will be with us for a long time, mainly due to its many desirable characteristics. No other material is like wood, which as it grows old in service has its beauty enhanced. Wood can be easily shaped by had or machine tools, be fabricated into a wide range of sizes by adhesives, dowels, nails or screws. Ancient craftsmen used to boast of gigantic structures completely built of wood without any metal fasteners. Moreover, damaged parts or components can be easily repaired or replace.