Paulownia is a timber that defies conventional expectations. Often called the "aluminum of timber" or "Empresswood," it combines an incredibly low density with a surprisingly high strength-to-weight ratio. For engineers, builders, and serious woodworkers, understanding the specific technical properties of Paulownia is crucial to unlocking its full potential in projects where weight, stability, and durability are paramount.
Key Technical Properties & Data
Unlike many hardwoods, Paulownia's unique cell structure results in a lightweight yet firm material that is easy to work with and highly stable.
Density: Paulownia's air-dry density typically ranges from 285 to 340 kg/m³ (18 to 21 lbs/ft³). This is exceptionally light, roughly one-third the weight of traditional hardwoods like oak and less than half the weight of common softwoods like pine. This low density is why it's a top choice for marine applications and lightweight structures.
Strength-to-Weight Ratio: Despite its light weight, Paulownia boasts an impressive strength-to-weight ratio. While its basic strength is lower than dense timbers, its lightness allows for the use of thicker sections without a significant weight penalty. This makes it an ideal material for applications that require structural integrity without the burden of heavy timber.
Dimensional Stability: Paulownia timber exhibits very low shrinkage and swelling. Its tangential shrinkage is around 1.8-2.0%, and radial shrinkage is 0.8-0.9%. These low values mean the timber is highly resistant to warping, twisting, and cracking, even when exposed to changes in humidity, ensuring your projects remain stable over time.
Hardness: Paulownia is a soft hardwood. Its Janka hardness rating is approximately 1.3-1.4 kN, which is significantly softer than a hardwood like oak. This characteristic is a key reason for its excellent workability and why it is not typically used for flooring or high-traffic surfaces.
Insulation & Sound Properties: The high porosity of Paulownia wood gives it excellent thermal and sound insulation qualities. It is a preferred material for musical instruments like guitars and ukuleles, where its ability to resonate sound is highly valued. Its insulating properties also make it great for beehives and construction projects where thermal regulation is a priority.
Fire & Rot Resistance: Paulownia timber has a high auto-ignition temperature of around 400°C (752°F), making it more fire-resistant than many other timbers. It also has natural resistance to rot and moisture, which is why it has been used for centuries in boat building and is a favorite for surfboards and other aquatic crafts.
Paulownia vs. Other Timbers
When compared to other lightweight timbers like balsa wood, Paulownia is a clear winner for most applications. While balsa is lighter (150 kg/m³), Paulownia is significantly stronger and more durable. This superior strength, combined with its resistance to water absorption, makes Paulownia the preferred choice for hollow-core surfboards, kayaks, and marine paneling.
Ready to start your project with Paulownia? Contact us today to discuss your timber needs and get a free quote. We offer a range of high-quality Paulownia planks and can provide custom cuts to your specifications.