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Paulownia

Paulownia has been used for a wide variety of purposes in China:

These include housing components, aircraft fittings, veneers, furniture, musical instruments, barrels, beehives, aqueducts, handcrafts, gift boxes, storage boxes, charcoal, wood pulp, coffins and pattern-making. In New Zealand it is likely to be used for specialist veneers, particularly for marine craft and surfboards, and furniture.

Description

paulownia_90Paulownia is a light, odourless, and easily worked hardwood. In colour it varies from silver-grey to light brown. It is the lightest known timber other than balsa, but is easy to dry and, although unsuitable for structural use, has physical and mechanical properties that are acceptable for other purposes.

It is straight grained and easy to plane to a glossy surface.  The pale brown heartwood is difficult to distinguish from the slightly lighter sapwood, which is only found in the outer 1-2 annual rings.

Blackwood and paulownia are included in Ministry of  Primiary Industries statistics which show a total planted area of 16,000ha in 2007 for hardwoods other than eucalypts and native species. The median age of these stands is less than 15 years.

Pauwlonia

Paulownia used in surfboard manufacture

Quick Facts

Botanical name: Paulownia tomentosa

Other common names: Chinese empress tree or princess tree

Strength: Neither hard nor strong but with a low density giving excellent buoyancy.

Durability: Overseas reports indicate that Paulownia has good natural durability, but results in New Zealand suggest that it should be classified as non-durable in ground contact, being no more durable than untreated radiata pine (<5 years in ground contact). The timber is also resistant to preservative treatment. It is resistant to insect attack.

Finishes: It is straight grained and easy to plane to a glossy surface.

Working properties: Paulownia is easy to machine, glue, carve, turn, sand and drill, due to the low density.

Appearance: In colour it varies from silver-grey to light brown.

Properties

The properties of Paulownia are neither hard nor strong, and the timber has very low density, giving excellent buoyancy.

Paulownia is easy to machine, glue, carve, turn, sand and drill, due to the low density.

Overseas reports indicate that Paulownia has good natural durability, but results in New Zealand suggest that it should be classified as non-durable in ground contact, being no more durable than untreated radiata pine (<5 years in ground contact). The timber is also resistant to preservative treatment. It is resistant to insect attack.

Mechanical Properties

Strength values refer to 20 x 20mm clearwood specimens. Please note these comparative measures of strength are “laboratory” values using standardised short lengths of clear timber. These will not be the same strength properties as structural lengths of timber.

For the properties of structural length timber please see the tables under the structural design section.

Density at 12% M.C. 340 kg/m3
Modulus of elasticity4.0 GPa
Bending strength40 MPa
Compression strength24 MPa
Hardness1.3 kN
Shrinkage green to OD, tang.2.0%
Shrinkage green to OD, rad0.9%

Case Study

NZ Kayak Builders_302x201

Pauwlonia is suitable for boat building such as for kayaks, as shown in this example, due to its excellent properties of buoyancy.

Availability

For suppliers of Paulownia timber and products refer to the Suppliers database or go to the NZ Farm Forestry Association Marketplace for availability of Paulownia