Paulownia lumber

[RDT]

Anyone know anything about this type of wood?
Sounds impressive according to this website. Light weight, strong.
http://www.paulowniasupply.com/paulowni ... istics.htm
http://www.paulowniasupply.com/paulownia_vs_balsa.htm
Claims that it has been used on Formula 1 boats
http://www.paulowniasupply.com/paulownia_uses.htm

[TomW]

Here are some other facts. Paulownia is the Emperor's tree of Japan and at one time anyone else having one in his possesion was beheaded. It is considered a weed tree and considered by the various states as an invasive tree that should not be planted in the landscape. Here where I live it grows wild on the side of the road. A few years ago it cost more than walnut and many people planted it. It grows very fast and can because of this reach lumber stage in a reasonable amount of time.

As far as boat building don't know anything more than what was in the articles. It is fairly new to the lumber industry and may or may not stay around do to the invasive label on it.

Tom

[Cracker Larry]

I've never used it, but it looks like it has many good qualities. Think I'll try to round some up

Wood Characteristics

Lightweight

Paulownia is about 2/3 the weight of the lightest commercial wood grown in the US. Average cubic foot weight varies between 15 to 19. This falls between Balsa wood and Poplar. Paulownia is 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

Balsa has been considered to have the highest strength to weight ratios of any wood in the world. Paulownia has been tested to have a higher strength to weight ratio than Balsa. Auburn University tested the strength of 18 lb p/cubic ft. against Balsa, with an average weight of 10 lbs p/cubic foot. (See Table 1)

Table 1

Strength of modus 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 could 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 would need to be purchased. When considering the large amount of epoxy that Balsa soaks up, Paulownia gains an even larger weight advantage.

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.

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. Furnitures, 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 ovendry 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 are fast growing trees that have a light blond appearance, similar to 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.

[frazoo]

Back in the early to mid '80's the stuff sold like it was made of gold. People actually started farms of it for the Japanese trade. I was commissioned to build three briefcases of it. Made damned good money on that job. It works well, is easy on your tools, although it really likes sharp tools. Like TomW said, it grows wild, I had a tree about 2.5' in diameter back behind my old shop. I used that tree for the briefcases. Free wood and a ludicrous commission!. I didn't understand the interest in it, it is not highly figured, kinda of a bland looking wood (if you like stuff like cherry and walnut, etc.) and to us, it was just a trash tree. One thing I have noticed over the years though, the limbs tend to break out very easily. I've always wondered about its sheer strength because of that.

frazoo

[Dog Fish]

I would like to plant some of those trees. Paulownia log house

[shine]

its all the rage with the wooden surfboard crowd.

[Sparky]

The Home Depots in my area, Northern VA, have been selling paulownia in shrink wrapped boards labeled "Edge Glued Hardwood Board." You can identify it mostly by its light weight but also the straight grain, no knots, color, and slight dill pickle smell when you cut it. I bought some to experiment with. Some strip canoe have been built using paulownia in lieu of Western red cedar to decrease weight. Every little thing adds up. For weight sensitive boats such as the LB22, you could shave a couple pounds by using it for cleats instead of pine.