You may have come across the Princess Tree, Royal Empress, or even heard it referred to as the aluminum of timber, which can understandably be confusing. Surprisingly, you might have encountered Paulownia without recognizing it.
If you want to know more, let me shed light on everything you need to know about Paulownia wood, what makes it so popular, and why it could be a fantastic choice for your upcoming project.
What is Paulownia Lumber?
Although dumped at most major ports all over the world, brought about by its unusual appearance, the Paulownia tomentosa also known as Paulownia tree, is one of the most versatile and hard-wearing wood types and tree species that grow around the world.
Paulownia is known for its light weight, number of uses, and rapid growth. The growth characteristic of the Paulownia is what began its demand in North America, after a series of deforestation that affected the United States.
A Paulownia tree can grow even in difficult parts of the world, especially where trees don’t normally survive, because the roots of the tree grow deep prompting tolerance even on inclines.
However, it’s still important to take note that while it’s less maintenance and can grow quickly, paulownia plantations should still be fostered. Paulownia has several uses from construction to bio-fuel so it’s best to know how to tend to wood species like this.
Common Name | Royal Empress, Princess Tree |
Scientific Name | Paulownia |
Genus | Paulowniaceae |
Tree size | 98 ft |
Janka hardness rating | 300 LBF |
Average dried weight | 18 lbs per cbft |
Shrinkage | Radial 2.4%, Tangential 3.9% Volumetric 6.4% Ratio 1.6 |
Modulus of Rupture | 5,480 LBF |
Elastic Modulus | 635,000 LBF |
Crushing Strength | 3,010 LBF |
Distribution | North America (Imported), China, Vietnam, Japan, Laos, Korea |
How Does it Grow?
Native to Southeast Asia, Paulownia trees are common and often used for different purposes, because it’s sustainable and easy to grow.
Paulownia trees are light and do not need lush and fertile soil, like most tree species, instead it thrives better in barren soil.
These trees grow faster than most species so foresters spread Paulownia seeds all over mountain regions which are vulnerable to wildfires and excessive sun exposure.
Another trip in growing Paulownia is to, make sure to plant as deep as 2-3 inches in well-drained soil, and a yard apart from each other. This allows the Paulownia tree to thrive well. Don’t let the soil poorly drain or become hard as this will cause distress to your growing tree.
Key Characteristics of Paulownia Lumber
Appearance and Color
The overall appearance and surface of a Paulownia, aren’t inviting to the western preference, but it’s unique and distinct.
The color and appearance of a Paulownia differ depending on its species type, and it can either be grey-brown with underlying tones of red and purple.
This wood appears with an eye-catching straight grain pattern and a silky shining surface finish.
The wood’s iconic growth rings set it apart from all other types of wood species, and it can be quite common to find in rainforests and mountain areas.
Endgrain
A wood’s end grain dictates its growth rings, and it’s visible when you cut it through. Often, the endgrain is used to identify a wood’s porosity.
The end grain of a Paulownia may come in ring types, large to small latewood pores, or narrow to medium rays. The overall pattern of the wood is more visible after it is cut.
Odor
Water is the main source of odor and aroma and since a Paulownia timber has small degrees of moisturization, it won’t absorb water, nor will it create an odor.
The princess tree, named after Russian Queen Anna Pavlovna has no odor and even the fruit’s outer peeling and surface are safe to be made as packaging materials.
Weight and Porosity
Paulownia is one of the lightest wood species in the world. Weighing only 310 per cubic meter, this wood is considered light weight compared to its common comparison, the native oak which has an average weight of 580 kg per cubic.
It’s also compared to western red cedar at 340 cbm, and teak at 750 cbm. Paulownia has low density, but still offers stability and is considered a porous material.
Strength and Durability + Janka Hardness Rating
Paulownia timber has an incredibly high strength-to-weight ratio, which is why even if it’s not considered a structural timber naturally, it’s considered an asset in various timber uses. It has a modulus elasticity of 5.6 GPa and a 28MPa modulus of rupture.
For durability, a Paulownia is similar to the western red cedar and needs at least twice the amount of water repellant for sealant. Commonly, epoxy resins and PU varnishes are enough to harden a finished surface, but Paulownia timber will need more.
Interesting Read: Is Epoxy Resin Food-Safe?
A light wood like Paulownia is not the best wood to use for areas that are frequently damaged. On average, the Janka hardness rating for Paulownia timber is at 1.3 kN, while a western red cedar is around 1.5 kN.
Workability and Finishing
Paulownia timber has straight grains and is one of the most light weight woods in the market which is what makes it easy to work with.
One setback you might encounter with working on Paulownia tree is its high blunting effect when cutting edges, brought about by its high silica [1] content.
Also, since a paulownia sap isn’t resinous based nor is it made of gum, applying finishes on the surface, won’t affect the timber quality, and in fact, make finishes even more excellent looking. Like all other types of solid wood, a paulownia deserves a good finish.
Uses
Paulownia wood is widely used around the world and has been a staple in the wood database of China and Japan.
This light wood has unique characteristics that made it popular even in European countries and is now used as a foundation when making common products such as the following:
- Aircraft and yacht fittings
- Veneers and furniture
- Musical instruments
- Paulownia surfboards (should be finished with linseed oil)
- Barrels and beehives
- Rice bowls and wooden boxes
- Wood pulp and wood shavings
- Aqueducts and handcrafts
- Paulownia timber turned into coffins
- Housing components
It’s also mostly used for millwork and other small specialty items that require intricate carvings and clogs.
Deformation and Warping
Paulownia timber stands out from other timbers due to its lower shrinkage coefficient. In terms of dimensional stability, Paulownia timber exhibits impressive numbers, with a radial coefficient of 0.094, a tangential coefficient of 0.268, and a volume coefficient of 0.362.
Thus, these coefficients indicate the timber’s ability to maintain its shape and size, with minimal changes caused by moisture content variations.
Rot Resistance
Paulownia trees no matter how capable of thriving even in the most difficult situations are still vulnerable to insect and rot infestation.
However, this is only when your Paulownia comes in contact with excessive humidity and moisture, so if you want your Paulownia to be rot-free, make sure it doesn’t get exposed to moisture.
Hence while it doesn’t do good with moisture, it can withstand water, as it’s one of the most common materials used in making watersport equipment, especially considering it absorbs lesser salt water than most wood.
The surface is still resistant to rot and insect attack provided there’s a generous amount of finish and sealant. Apart from this, it has low density making it best suited as firewood too, but not for construction.
Toxicity
Wood isn’t naturally toxic, but there are still some elements in wood that are toxic and hazardous, which is why most wood species that have these qualities, are advised to be burned to release toxins.
The good news, however, is that Paulownia trees don’t contain any toxic elements, and being exposed to it even for long periods isn’t problematic.
Hence I still recommend taking extra precautions when working with Paulownia, such as wearing appropriate gear both when cutting and transporting wood.
Allergies
Fortunately, there aren’t any allergies that are associated with Paulownia trees, nor are there health restrictions. However, if you’re allergic to wood dust, you might want to stray away from wood shavings instead, to avoid further complications.
Conductivity
Coined one of the fastest growing trees, it’s no wonder why there is a lot of paulownia plantation sprouting all over the country. It’s also an excellent insulator and has twice the R factor as oak wood and pine wood.
Most hardwoods can go around 220ºC, hence a Paulwownia can do double such fire resistance.
Thermal Insulation
Paulownia has very minimal thermal conductivity, only about 0.07 Kcal/m/hr. Also, Paulownia timber has the best heat and thermal insulation as well and is even better than concrete and steel.
Fire Resistance
Most properties of Paulownia are often not found in most woods, including how fire resistance it is. It has high conductivity and has lower flame spread rate than most of the building codes in the US.
Pricing and Availability
Paulownia wood prices are more expensive when sold domestically, and while it’s common in the United States, it’s not for sale. Japan has higher demands for this wood, which explains the humongous number of Paulownia plantation in the area.
Sustainability
A royal Paulownia isn’t included in the lists of threatened or invasive species, so it’s safe to harvest these types of wood, especially if you’re in the Asia region.
However, one possible reason why it is kept within bounds is that harvesting it outside of Asia can be pretty challenging.
Hence, the fast-growing properties of Paulownia make it a sustainable material for making wood stuff such as musical instruments and wood boards. Also, it can be harvested as early as five years and converted into Paulownia timber.
Other Facts
- Low shrinkage
- Resistance to insect damage
- Excellent dimensional stability
- Fungal rot resistance
Photos
Advantages of Paulownia
Easy to Grow
Apart from Paulownia timber being of average weight, its versatility and adaptability make it a favorite amongst woodworkers. Also, Paulownia is notorious for growing easily so acquiring it won’t be too much of an uphill battle.
Lightweight
A Paulownia weighs half the weight of pines, and it comes with a sparse grain structure that makes it easy to work around. The low weight of this wood makes it less dense, meaning you can use more of the wood itself.
However, one dilemma you might encounter, is that this wood may not be as strong, so we find it suitable for heavy-duty construction.
Knot-Free
If you’re looking for a wood specie that will look good when converted into a furniture piece, then a paulownia may be one of your best options.
It doesn’t have uncertain knots that ruin a wood grain aesthetic, nor does it make cutting tools dull easily. Woodworkers opt for lesser knots as it is more durable and aesthetic.
Highly Durable
Paulownia trees can withstand even strong winds and pressure, and most of the time even rocks and mudslides. Its durability is one of the characteristics that make Paulownia timber an excellent material for making musical instruments.
Like oak wood, it lasts unfavorable conditions, and is rot resistant, provided it’s kept well-ventilated. The Paulownia roots grow deep in the soil, which explains its high tolerance even on heavy wind and steep inclines.
Insulation
Wood, even in its natural state is a good insulator of heat and provides exceptional warmth even when compared to electric blankets and space heaters.
This makes Paulownia timber the perfect insulator for houses and commercial buildings. It’s primarily used as an insulation material which increased its demand, especially in Asia.
Versatility
The wood sourced from Paulownia trees are versatile and every part of them has uses and applications. Its wood can be used as material for wood board, veneers, and plywood, while the fruit’s peels are used for packaging.
If you’re in a forest and you’re trying to look for a Paulownia timber, looking for its flowers and seed pods is a good identifier.
Paulownia wood offers a fascinating array of possibilities, making it a versatile choice for various purposes. Whether you’re crafting furniture, engaging in light construction projects, or even working on sailing materials, this wood can be an excellent option.
Its versatility extends across many sectors of the wood industry, where it’s prized for both its aesthetic qualities and practical utility.
FAQ
What are the disadvantages of Paulownia?
The common disadvantage of Paulownia is the brittle wood characteristic, making it susceptible to insect attacks. The tree and slabs are lightweight, and its wood surface is easy to scrape and scratch. There aren’t indicators the leaves of Paulownia are dropping, as it doesn’t change in color.
Which is better, pine or paulownia?
Paulownia and pine wood are compared due to their very similar characteristic. What sets them apart is their availability. Besides, pine wood is more challenging to adjust with, so Paulownia timber is the better hardwood.
Let’s confirm: Is Pine a Hardwood or Softwood?
Conclusion
Discover the remarkable potential of Paulownia wood and the endless possibilities it offers, thanks to its rapid growth. If you’re seeking a wood variety that’s not only eco-friendly but also incredibly versatile, look no further than Paulownia. It’s the savvy choice for your woodworking projects.
You've probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.
Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.
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