Paulownia wood, also known as kiri or princess tree, is a material that over time has gained popularity thanks to its unique characteristics. Of Chinese origin, it has spread throughout Asia for centuries, where it is well known and used. It was only recently introduced in the West and there are more and more uses for this exceptional wood. In Spain, it can be said that it has just arrived and, although there are some plantations, what has been called industrial exploitation has not yet been reached. Instead, these are small tests to explore the country’s possibilities.

From this tree not only is wood used, flowers and leaves also have uses. This is the tree rapid growth, As the bamboo, widely used for restocking in areas where there is a risk of soil erosion. In 10 years they can reach fifteen meters in height. After being cut down, and if the roots are respected, the tree grows back much faster. This is one of the reasons why it is also known as «phoenix tree«.

There are several types of paulownia. From a commercial and productive point of view, species whose scientific name is Paulownia tomentosa. This is the one with the best features.

It is also worth mentioning that there are important differences, much more than in other woods, in the physical-mechanical characteristics (density, hardness, elasticity …) of paulownia depending on how it was grown and its conditions.

Paulownia wood Characteristics

Color: Together light or pale color it is often compared in appearance to ash. Yellowish-white sapwood, light gray-brown heartwood. Heartwood and sapwood are not clearly differentiated. Without us.

Fiber: Direct.

Grain: Thick.

Density: Light wood with an approximate density of 265-280 kg / m3 at 12% humidity.

Toughness: This is a soft wood with 1.3 in the Monnin test. It offers an excellent relationship between hardness and density. Keep in mind that although it is not a hardwood, it is one of the lightest woods out there.

Durability: Moderate. Good resistance to rot, although susceptible to attack by insects. Can be used outdoors, although protected (covered).

Dimensional stability:

  • Volumetric shrinkage coefficient: slightly edgy wood, between 0.26-0.33%

Mechanical properties:

  • Compressive strength: 211 kg / cmtwo
  • Static flexural strength: 440 kg / cmtwo
  • Modulus of elasticity: 44,600 kg / cmtwo

Workability: Very easy to work, due to, among other things, its straight grain and lightness.

  • Sawn. No problem, although in parts with a high silica content, a numbness problem can occur.
  • Drying. Fast and without noticeable problems. Outdoors, between 40 and 50 days are usually sufficient. In drying ovens the process can be reduced to 48 hours. Low risk of warping.
  • Brushed. No complications, like sawing.
  • Glued. Smoothly.
  • Nailed and screwed. Smoothly.
  • Finish. Requires the use of products to seal the pores.

Price: Where it is grown it is quite low. The place where it is not produced and its final value is imported depends basically on transport costs and the number of intermediaries. There is great variability in the price of paulownia wood depending on the source and quality. The trend is clearly downward, mainly due to the increase in supply.

Paulownia wood can be purchased in several formats: planed and unbrushed boards, slatted boards, plywood and even laminates.

Kiri wood uses

  • Furniture. The excellent dimensional stability of Paulownia wood makes it the ideal choice for the manufacture of quality furniture and cabinets. Its low cost also makes it an option for the manufacture of structures for interior furniture that will later be covered with wood of greater value.
  • Interior carpentry: doors, frames, frames …
  • Carvings and musical instruments, mainly traditional oriental instruments, but also more current ones like paulownia wooden guitars.
  • Surfboards or kitesurf. This is a field where this type of wood is arousing great passions. For those who use traditional tables made of wood the discovery of this material was a revolution.
  • Construction of vessels and other means of transport, not necessarily maritime, although they are the most frequent. Also caravans or airplanes, thanks to its lightness.
  • Manufacture of plywood, solid or strip sheets.
  • Widely used in the manufacture of saunas thanks to its natural resistance to moisture. Also is common ayous sauna
  • Packing
  • Camper van
  • Like cork, it can be used as an acoustic and even thermal insulator.
  • In places where paulownia wood is abundant, it is also used for the manufacture of posts or poles that will be used outdoors, taking advantage of its great resistance to moisture.
  • Given the rapid growth of the plant and its abundance in some areas, it is an excellent choice for biomass plants.
  • This tree can also be used to obtain fodder for livestock. The leaves can reach up to 70 centimeters in width and also have good nutritional values ​​for cattle.