Joinery and Interior Fittings from Radiata Pine
New Zealand radiata pine sawn timber is the international choice for a wide range of interior fittings and fixtures, including windows, doors, frames and jambs, mouldings, stairs, cabinetry and bench tops.
A number of properties of radiata pine contribute to it’s wide use for these varying products.
1. Texture & Appearance
One of its unique properties is it uniform density, i.e the small variation in density between spring wood and summer wood within a growth ring, It is this property which confers on radiata its excellent machining, painting and staining properties.
Consisting mainly of creamy white sapwood, with prominent fine resin canals, it presents a uniform appearance with little colour variation between pieces. This is as advantage for subsequent finishing.
2. Machining
Comprehensive tests undertaken at Forest research, Buckinghamshire College of Higher Education in England, and University of California, Berkely (USA) have shown that radiata has machining properties (cross-cutting, turning, planing, moulding, boring, sanding) equal or superior to many of the internationally traded softwoods. Its fast growth does not adversely affect its working properties and good results can be obtained with all types of hand and machine tools.
3. Finishing
The full range of interior and exterior stains, oils, varnishes and paints may be used on radiata pine. The absence of high concentrations of extractives prevents and incompatability with finishes and eliminates the need for special primers. A very high standard of finishing can be obtained. The wood can be stained to resemble a wide range of lumber species.
4. Fastening
being of medium density and even texture and having good resistance to splitting, New Zealand Radiata Pine can be nailed particularly well. The same properties allow the prodiction of efficient joints using other systems, e.g. screws and proprietary connections. Low extractives content and uniform density allow achievement of above-average glued connections, e’g. dowels and finger-joints. The high strength of glued dowel joints (compared to other species, e.g. meranti) is due to the contribution from the end grain to the joint.
5. Dimensional Stability
This is a crucial wood property for interior fittings and joinery uses. Radiata pine has a low shrinkage which contributes to its stability. However, stability is also affected by a number of other properties, including; equilibrium moisture content, straightness of grain, spiral grain, rate of moisture uptake, permeability to liquids and gases.
Long term movement is the property which best describes the dimension changes which occur when joinery is exposed to dry summer conditions and later to wet winter conditions. The dimensional response of cladding and joinery when exposed to fluctuating weather conditions, such as alternating rain wetting and sunshine, is best described as short-term movement.
Because of the presence of spiral grain, the corewood of radiata pine should not be used where stability os vital to performance.
Dimensional performance can be increased by use of finger-jointing, and/or lamination. Such highly processed laminated, finger-jointed clear products are used widely across the world where maximum stability is required; e.g sliding door tracksm (kamoi and shikii), mouldings and door frames.
6. Durability
Radiata Pine Sawn Timber must be preservative treated for exterior uses. However, it is one of the most permeable wood species and can, therefore, be acceptably treated by pressure impregnation, double vacuum and simple immersion methods.