Paulownia vs Balsa

Paulownia Wood... the Cheaper, Stronger Alternative to Balsa Wood

Balsa has been incorrectly considered to have the highest strength to weight ratios of any wood in the world.

Paulownia has been thoroughly tested and found to have a higher strength to weight ratio than Balsa!

Auburn University tested the strength of 18 lb p/cubic ft. Paulownia against Balsa, with an average weight of 10 lbs p/cubic foot.

(See Table 1)

Strength modus of rupture mor (psi)
Balsa 2800
Paulownia 5740
- Source: Dr. R.C. Tang, Auburn University

Some Balsa core material is sliced at 3/8 inch with end-grained material. Paulownia can be cut at 3/16 and offer approximately the same strength and weight. Paulownia offers a space saving benefit, being cut half as thick. There is also a significant cost savings because half as much material is needed.

Lighter grades of Paulownia weigh only 14lbs per cubic foot. This is lighter than many Balsa grades.

When considering the large amount of epoxy that Balsa soaks up, Paulownia gains an even larger weight advantage.

Paulownia is easily carved and can hold nails and screws without splitting. It also provides greater stability and flexibility for making molds and models.

Paulownia Lumber Characteristics

Tags: paulownia, lumber characteristics, paulownia strength, balsa, aluminum of hardwood, conductivity, fire resistant, insect resistant

Lightweight

Paulownia is about 2/3 the weight of the lightest commercial wood grown in the US. It weighs an average of 14 to 19 lbs per cubic foot. Paulownia is almost 1/3 the weight of Oak (44 lbs p/cubic ft) and half the weight of Pine (30 lbs p/cubic ft).

The specific gravity of Paulownia ranges between 0.23 to 0.30 (23 to 30% of the density of water).

Strength

Paulownia has one of the highest strength to weight ratios of any wood.

Strength modus of rupture MOR (psi) of Paulownia is 5740.

Paulownia holds nails and screws well and does not require pilot holes to be drilled. In fact both yellow poplar and white pine have proven to split before Paulownia. Flat head screws can be driven flush with the surface.

Plantation grown Paulownia is mostly knot free, making it very consistent.

Workability

Paulownia has been widely used in the orient for fine furniture, musical instruments, carvings and decorative finishes for over 1000 years. It can be peeled for veneer in 1/16 inch thickness and has even been sliced at 1/32 inch.

Intricate patterns can be cut with a jig saw or band saw without splitting easily. Paulownia has been a favorite for many carvers in the US. Furniture, doors and windows can be made with close tolerances. All normal finishing materials can be applied and it bonds well with glue.

Stability

Air-drying takes as little as 30 days. Boards can be kiln dried at high temperatures in as little as 24 hours to 10% to 12% moisture content with no warping. Reported shrinkage from green to oven-dry is only 2.2% radial and 4.0% tangential.

Paulownia remains stable during changes in humidity and experiences little shrinkage or expansion compared to most other woods. It is highly durable and resists decay under non-ground contact conditions. The wood is insect resistant.

Conductivity

Paulownia is a very good insulator. Paulownia log homes are said to have twice the R factor as pine or oak logs. This temperature resistance serves to give the wood a high fire resistance. Ignition temperature is approximately 400 deg. C. which is almost twice many conventional American hard and soft woods.

Attractiveness

Paulownia has a light blond appearance and resembles White Ash. It stains well with a variety of colors and can be made to mimic other woods. Once planed a silky luster is revealed. The feel is also very silky.

For more information on paulownia or to purchase paulownia seeds or seedlings (elongata, fortunei, tomentosa) please refer to http://www.paulownianow.org or http://www.panampro.com

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