55
Classification of Timbers
This article, and the further instalments to be published in subsequent issues, are condensed from a series of lectures given to members of the P.W.D. by Mr. I. P. Tamworth, M.C., Forestry Officer, Hong Kong Government. We are indebted
to Mr. Tamworth and the Hong Kong Government for authority to publish this information. We believe it will be of great interest to all those dealing with and using timber in Hong Kong and perhaps in other places using the same timbers and having a similar climate. A better understanding of the characteristics of various timbers makes it possible to select the wood must suitable for its requirements.
The two big groups into which all timbers can be broadly classified are:-
(1) Conifer.
(2) Non-conifer. (Hardwood).
The timbers making up the first group, arising as they do from trees which bear seeds in a cone-like structure, produce wood which is anatomically different in structure 1rom the wood of the group of non-conifers. Apart from the fact that the distribution of conifers throughout the world shows a general tendency towards the temperate and sub- tropical regions as opposed to the tropical, ine same cannot be said of the non-comfers which extend from the Arctic to Tropical regions. Do not however think of conifers exclusively as evergreen and non-conifers as deciduous trees, or think of coniters as producing a soft wood and non-coniters as producing a hard wood, as Baisa, which is the lightest and softest timber in the world, is considered as a Hardwood, as also are willow and poplar, the wood of which is lighter and softer than any conifers. Likewise the wood of many conifers as Yew and Long-leaved pitch-pine are harder and heavier than many hardwoods. If therefore you see "soft- woods" used for conifers, as is very commonly done, it is essential to bear in mind that though conifers generally pro- duce a softwood the converse is not nearly so often true i.e. that Hardwoods produce hard or durable timber,
This classification will hold water from an anatomical point of view, whilst from the utilisation point of view it is not necessarily a convenient basis for classification, and in point of fact the only basis of classification which is acceptable must be a 1ocal one and must depend on the timbers found on the market of the region to which that classification is to be applied. In Hong Kong it is desirable to recognise five main groups of timber as under:—
Primary hardwoods (Heavy).
(1)
Conifers.
(2)
Teak.
(3)
(4)
(5)
Secondary hardwoods (Medium heavy). Light hardwoods.
The trouble, however, of dividing non-conifers into four distinct groups is that some artificial distinguishing line has to be drawn in this case between the primary hardwoods and secondary hardwoods and the secondary hardwoods and the softwoods. Consequently in identifying the timbers on the Hong Kong market it will be necessary to distinguish anatomi- cally the conifer from the remaining classes of timber and the differences of the other three classes by the physical properties and differences in the arrangement of the ceils comprising the structure of the wood.
THE HONG KONG TIMBER MARKET.
On the above mentioned basis of classification, the timber imports into Hong Kong during 1947. 48 were as follows:-
(1)
Conifer. 33% (China fir and Pine 20%, Douglas Fir 13%, Canada & U.S.A.).
(2) Teak 7% (Siam).
(3) Primary Hardwoods. 6% (Borneo).
(4)
Secondary Hardwoods 33% (Borneo 18% Siam 12% F.M.S. 3%).
(5) Light Hardwoods 21% (Borneo 8%, F.M.S. 5%.
U.S.A. 5%, China 3%).
Nearly all exports of timber to Hong Kong from Malaya are sawn except for timber used for veneers for match boxes. Since the war nearly all timber exported from Borneo has been in log form but latterly with the rehabilitation of the saw mills in that country increasing quantities of sawn timber may be expected.
Other relevant details are given below under the specific timbers.
All exports of timber from Hong Kong are re-exports and amounted to about 10% of the imports in 1947/48, though the re-exports would normally be higher were the current pro- hibitions on timber imports into China removed.
The sources of supply of timber for the Hong Kong market are essentially the tropical rain forests of S. E. Asia. These forests are composed of a large variety of species only some of which produce marketable timbers. The outstanding timber produced in these regions is Teak which at present is coming in considerable quantities from Siam. The other timbers from this area are most conveniently classified into the groups mentioned at (3)-(5) (above). No conifers of commercial importance grow in the tropical rain forests of S. E. Asia.
(a)
The chief uses of these coniferous timbers are as follows:-
DOUGLAS FIR OR OREGON PINE (Pseudotsuga taxifolia). (花逛粉板)
This timber is shipped both from Canada and West Coast of America always in board form and in the financial year 1947 48 those shipments totalled about 500,000 cu. ft. It is one of the most widely used of all softwoods, being excep- tionally strong and hard. As flooring or decking it takes a good polish and wears well. It has an excellent figure for veneer panels. It is used in Hong Kong also for cement shuttering boards in preference to China fir as it can be used time and time again for this purpose. It is an all purpose wood.
(b) CHINA FIR. (Cunninghamia sinesis).
(Chaam Shue)
(杉樹)
This tree grows extensively over Central and Northern Kwangtung. After felling the stems are made into rafts and floated down first to Canton and from there to Hong Kong. Consequently it always arrives in Hong Kong in log form. The smaller logs are commonly used for scaffolding polcs and beards whilst the larger logs which, incidentally, rarely exceed 1 ft. in diameter, are sawn up for cheap furniture. The wood is extensively used in building squatters huts, cement-boards and in junk building in Hong Kong (masts and hull).
CHINA PINE (Pinus Massoniar.a) (Chung Shue)
(c)
(松樹)
The import cf this timber into Hong Kong is negligable as compared with the first two. It sometimes arrives in log form having followed a similar course to China Fir and sometimes arrives by coastal steamer from Amoy or Foochow sawn into planks. The logs can be used for making veneers for match boxes, meat boards, and boards for cheap structural work. It is the chief source of firewood for Hong Kong.
(d)
FORMOSAN PINE,
Recently used by P.W.D. for tables and furniture in Architectural and Crown Lands Offices. This timber was imported in large quantities during the occupation of the Colony by the Japanese, and used chiefly for interior decora- tion and furniture work. The tree appears to be very susceptible to heart-rot, leaving the butts with large holes extenwing up to of the diameter of the tree, thereby causing a large degree of wastage on conversion.
NON-CONIFERS.
The timbers of this category on the Hong Kong market are commonly grouped as follows: —
(1) Teak
(2) Primary Hardwoods (heavy):-
Balau (Selangan Batu). Billian.
(a)
(b)
(c)
Selangan Batu No. 2.
(d)
Chengal.
(e)
Selangan Batu Merah.
(f)
Merbau.
(g)
(a)
(b) Kapur.
(c)
Keruing.
(d)
Other species.
(3) Secondary Hardwoods (Medium Heavy):-
Camphor,
Kempas.
(e) Gagil.
(f) Other species.
(4) Light Hardwoods (Often known locally as
TEAK.
softwoods):-
(a) Serayas, Merantis etc.
(b) Nyatoh.
(c) Sepetir.
(d) Other species.
Sak,
(Tectona Grandis) Siamese name:
Chinese name: Yau Muk (*)
Teak is too well known to you to require much introduc- tion. Coming from Siam and Burma it is considered by many as the most outstanding timber in the world. Its greatness lies in its relatively small shrinkage in drying out which is only 2.3% radially and 4.2% tangentially combined with its relatively low hydroscopic qualities. It is very easy to work and highly resistant to both insect and fungal attack. It is strongly fire and acid resistant and has not the corrosive action upon iron which oak has. It is fairly durable in contact with the ground or sea water but does not compare in this respect to Billian or Balau. Mechanically it is stronger than oak but much weaker than Billian and Balau. Burma teak is the strongest of all teaks, the Indian, Javanese and Siamese Teak are milder and more decorative in appearance. Its weight is only about 45 lbs. per cu. ft. but it varies greatly with the locality of origin.
Since 1945 practically the entire requirement of Hong Kong for Teak has been shipped from Siam. It is usually shipped either as "conversions" including Planks, Boards, Scantlings, Floorings, Laths, Stringers and Deckings, or "squares" which are squared logs of varying dimensions.
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