NEW ZEALAND STATE FOREST SERVICE.

BRANCH OF FOREST PRODUCTS.

LEAFLET No. 15.

E. PHILLIPS TURNER, Director of Fo-restry.

The Properties and Uses of Taraire ( tarairi).

By ALEX, R. ENTRICAN, Engineer in Forest Products.

GENERAL. THE Beilschmiedia species constitute one of the most important com­ mercial groups of hardwoods in New Zealand, being second only to the N othofagus or Southern- species. In supplies available and in geographical distribution the tawa () is undoubtedly the most important member of the group, but in the North Auckland Peninsula this species is often replaced by the taraire (Beilschmiedia tarairi). The of the taraire is somewhat heavier, stronger, and darker in colour than that of the tawa, and has been extensively employed for mouldings, interior finish, and furniture. It is occasionally referred to as New Zealand , flat sawn boards having some resemblance to those of some of the true (Quercus species).

THE TREE-ITS FOREST FORM AND ASSOCIATES. While the taraire is rarely a dominant tree, it is usually the most important species in the lower story of the kauri ( australis) and mixed forests of the North Auckland Peninsula. Other major associates in this region are rimu ( cupressinum), miro (Podocarpus jerrugineus), and totara (). The most important minor associates are (Vitex lucens), towai (Weinmannia sylvicola), and tanekaha (Phyllocladus trichomanoides). The taraire has a straight erect bole, fairly free of branches, and with a diameter breast-high from I ft. to zt ft. The tree commonly attains a height of from 50 ft. to 70 ft.

RANGE AND SUPPLIES. The botanical distribution of the species covers practically the whole of the northern part of the Auckland Province, but commercial supplies are restricted to the North Auckland Peninsula, its distribution south of Auckland City being only local. z

The taraire is essentially a lowland species, and is seldom found above an altitude of l,200 ft. above sea-level. No estimates of available supplies are procurable, but it is probable that the forests in which this species occurs will total over 200,000 acres. As 80 per cent. of these forests, however, carry a total stand of all species of less than about 5,000 ft. b.m. per acre, the total available supplies are not large.

PRODUCTION. The annual cut of taraire is small, the average reported by the Government Statistician for the period 1921-27 being about 107,000 ff. b.m. The largest cut is that recorded for the year ended 31st March, 1922, when 188,ooo ft. b.m. were produced. Generally only two grades are produced--clean and seconds. The market for clean is fairly good, but seconds are disposed of as cull timber, and· are of little value. To secure the best results, logs should be hauled to the mill imme­ diately after felling, sawn at once into timber, and the boards carefully filleted and roof-stacked. Otherwise the timber is liable to fungal attack resulting in sap-stain or/and decay.

PROPERTIES OF THE WOOD. PHYSICAL CHARACTERISTICS. The dry heartwood is light brown in colour, with a distinct pinkish tinge. The sapwood is whiter in colour. Although very similar to tawa, taraire has several outstanding characteristics. It is heavier and stronger than tawa. On quarter-cut surfaces the rays are inconspicuous, whereas on tawa they are prominent. The colour of the wood is also distinctly brownish and pinkish compared with that of the other member of the genus. It occasionally exhibits the blackish discoloration so common in tawa. The wood is remarkably straight in the grain and easily split. Owing to the size of the pores, it appears to possess a coarse texture, but it machines and finishes exceedingly well.

DURABILITY. Taraire is not durable in contact with the ground, but saplings can be treated with creosote to furnish fencing-posts of good durability. The sapwood is si.;i.sceptible to borer-attack, especially by A nobium domesticum; but wood-users are recommended to eradicate borer­ attack in their houses, &c., rather than allow the continued existence of these insects, and to use the more resistant heartwood and other species. It is not generally recognized that after timber-boring insects have exhausted their food-supply in sap-wood they will extend their activities into the heart-wood of most species. With proper care, there­ fore, both the sapwood and heartwood of taraire may be used with all - confidence.

MECHANICAL PROPERTIES. Standard tests on a large number of small clear specimens of taraire .and post-oak gave the following results:- 3

Taraire. Post-oak.

Properties. ---~··--~------~--- Green. Air-dry. Green. \ Air-dry.

I Rate of growth (rings per inch) 27 26 i Summer-wood, per cent. . . · g 54 I Moisture content, per cent. (based on 104 I2 69 : 11•2 oven-dry weight) Specific gravity (oven-dry, based on 0·565 0·598 0·60 0·68 volume at test) Weight per cub. ft. at test (lb.) 72 42 63 47 Static bending- Fibre-stress at E.L. (lb. per sq. in.) 5, 550 8,060 5,000 7,800 Modulus of rupture (lb. per sq. in.) 8,580 ' 12 ,990 8,100 13,600 I, Modulus of elasticity (lb. per sq. in.) 409, ooo I I' 787' OOO ,090,000 ,540,000 Work to E.L. (in. lb. per cub. in.) r·33 ~ 2·16 r·3r 2·34 Work to M.L. (in. lb. per cub. in.) r2·or 8·94 I r·o 13·3 Compression parallel to grain- Crushing strength at E.L. (lb. per 3, 060 5,380 sq. in.) Maximum crushing strength (lb. 3, 870 6,640 per sq. in.) ·Compression perpendicular to grain- Crushing-strength at E.L. (lb. per 840 1,340 l,060 l,900 sq. in.) Hardness (load to imbed a 0·444 in. ball to one-half its diameter)- Side (lb.) 800 l ,040 l,130 l,390 End (lb.) 860 l,290 l, l6D l,360 Shear parallel to grain (lb. per sq. in.) l, ooo l,910 I,280 l ,goo ·Cleavage (lb. per in.) . . . . 250 420 Tension perpendicular to grain (lb. 550 720 790 780 per sq. in.)

By comparing these results with those of a corresponding series of tests on North American it is apparent that taraire possesses much the same physical and mechanical properties as a number of the oaks (Quercus sp.). Those, for instance, of American post-oak (Quercus minor) have been included in the table for reference. Generally speaking, taraire is not as strong as the very best of the oaks, but is equal to or superior to many members of that genus. The green values should be used to formulate working-stresses.

UTILIZATION. GENERAL. Owing to the limited supplies of taraire coming on to the market the wood has not been widely used. The greater part of the sawn product has been absorbed by the moulding and furniture manufac­ turers, a small quantity also being used by boxmakers. Generally speaking it should prove useful for most purposes for which the oaks are employed. As with all other timbers, the secret of its wider utilization lies in improved seasoning practices.

BUILDING-CONSTRUCTION. For moulding and interior finish taraire is a desirable wood, its pleasing grain, its machining or finishing qualities, and its staining and polishing properties making it especially suitable for such purposes. 4

. The wood is also suitable for hardwood flooring, narrow kiln-dried stock, secret nailed to a sub-flooring, being recommended. The use of proper flooring-brads will minimize splitting when nailing through the tongue. FURNITURE AND FIXTURES. Good strength and stiffness, combined with excellent finishing qualities, make taraire suitable for the manufacture of many classes of furniture and fixtures. The wood should find extensive use for bedroom and dining-room furniture, for bookcases, for office furniture, such as tables, chairs, and filing-cabinets, and for bank, office, and church fixtures, such as desks, counters, show-cases, pulpits, and pews.

VEHICLE AND CAR CONSTRUCTION. For the framework of motor bodies and of tram-cars and railway­ carriages taraire is useable only where it will not be subjected to damp or to alternate wet and dry conditions. For seats and interior finish it is entirely suitable, forming a desirable substitute for some of the imported woods at present employed for these purposes.

TURNERY, WOODENWARE, ETC. Dowels, broom-handles, door and drawer handles, and many other minor turnery and woodenware products are producible from taraire.

FARM USES. Taraire makes a fairly good firewood, and burns rapidly. Round posts may be creosoted to give good service as fencing-material.

TYPICAL MICROSCOPICAL CROSS-SECTION OF T ARAIRE. X 50.

By Aut.hority: W. A. G. SKINNER, Government Printer, Wellington. [r,ooo/:i/30-r5ozz