One of paulownia’s greatest attributes is that it’s both lightweight and strong. In fact, paulownia is the lightest wood in the world (after balsa).
The timber’s low density provides excellent buoyancy, making it highly suitable for boat building, surfboards and kayaks.
The most common test for measuring wood hardness is known as the Janka hardness test. The actual number listed in the wood profile is the amount of force required to embed a .444″ (11.28 mm) diameter steel ball into the wood to a depth of half the ball’s diameter. The results are stated in various ways in different countries – in Australia and New Zealand, Janka hardness ratings are either in newtons (N) or kilonewtons (kN). Paulownia has a Janka hardness rating of 1.3-1.4 kN.
And just in case you’re curious, the heaviest wood in the world is black ironwood. It’s found in southern Florida, the Caribbean, and Central America, but is rarely available for sale, since the tree itself is very small.