Radiata Pine

(Information compiled by the New Zealand Forestry Service) CLICK HERE FOR LINKS ABOUT NZ WOOD

Availability

The standing volume of Radiata Pine in New Zealand was estimated at 338,000,000 cubic metres which increased to 353,000,000m³ in 1999. It is likely that significantly greater quantities will be available into the new millennium.

General Description

Radiata Pine is a light-coloured softwood with a moderately even texture.

Drying

Radiata Pine is extremely easy to season and can be kiln-dried rapidly from green. Material from near the pith is prone to twist, cut twisting can be minimised by good stacking and restraint. Timber that is pressure treated with waterborne preservatives using the Bethell (Full-Cell) process redries slowly.

Durability and Preservation

The timber is non-durable, but it can be readily treated with preservative. The wood is prone to sapstain attack, but this can be combated by a dip treatment.

Physical and Mechanical Properties

There is a consistent pattern of density increase outwards from the pith, with a tendency to level off as wood reaches 15 to 20 years of age. The corewood, which is usually confined to the innermost five rings, has a very low density and has shorter fibres and higher longitudinal shrinkage than the outer wood. The density of the outer wood varies considerably between tress and is closely related to the mean annual temperature of the site where it is growing. Timber of trees grown in northern parts of the country and at low altitudes generally has a higher density and consequently higher clearwood strength. The inner heartwood rings show a relatively high resin content in comparison to outer wood. Resin pockets in radiata pine are typically lens-shaped. Although they occur in trees in all parts of the country they are more prevalent in some areas, particularly Canterbury.

Other than the defects associated with the weaker corewood zone, such as pith and spiral grain, the main defect found in the sawn timber is that of knots, and to a lesser degree resin pockets.

The incidence of compression wood is greater in old untended stands, and is associated with stem deviation and malformation. It can be expected that the 'classic' compression wood, characterised by darker wood and accentric radial growth, will become less common through the use of genetically improved planting stock and the adoption of strict silvicultural practices.

The change in raw material supply from untended 'old crop' to thinnings and produce from intensive managed stands will result in some significant changes in average wood properties. Apart from pruning operations enabling more clearwood to be produced the main anticipated effects are a consequence of the stands being younger at the time of harvest. On balance, the sawn timber produced from 'new crop' stands will have a lower density, a higher proportion of corewood, a smaller proportion of heartwood and consequently a high moisture content.

Working and Finishing Properties

The wood machines and nails well, and has good glueing and painting properties. It is not easy to steam bend in an even curve.

Uses

The range of uses to which radiata pine may be put is extremely wide. It has been used for poles, posts, plywood, and pulp and paper, and has many other uses such as for boat building, laminated beams, construction work, pallets, sleepers, furniture and joinery.

It thus fulfills a very wide variety of functions, and only for a few specialised uses is it considered unsuitable.