Send a PM to Stripercrazy and see where he purchased his from. It was over 20lb p/cubic ft. He sent me a sample and it was too hard for me to want to work with.
If you like hard balsa you might want to try Paulownia wood.
The density of Paulownia is a consistent 15lb-19lb p/cubic ft. Slow growth trees weigh a little more and fast growth trees weigh a little less. The fast growth trees might have up to 2 inches between some of the rings. The feature I like best about it is the weight of the wood being so consistent from one end of the board to the other. I have weighed identical cuts form the same board of Balsa, no more than a foot apart and one piece might weigh 1.8g and the other might weigh 3.1g. When I have done the same test with Paulownia the difference in weight is much less.
Here is a little information on the wood. Two cut and paste from other web sites.
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.
PHYSICAL PROPERTIES OF PAULOWNIA.- Paulownia is light weight 17 to 21lbs per cubic foot as compared to Appalachian Red Oak at 39 to 41 lbs per cubic foot.
- Paulownia air dries in 30 to 60 days without cupping, warping, cracking or splitting. Kiln drying takes 36 to 60 hours depending on Dry kiln configuration, horsepower and dimension of lumber.
- Paulownia is resistant to decay and rotting provided it is not in permanent contact with the ground.
- Paulownia species vary in porosity according to Variety but range from 75 to 88% in comparison with poplar 70 to 72%.
- Fire resistance is a feature of all Paulownia, Ignition temp 420 to 430 deg Celsius as compared to Average hardwood at 220 to 225 deg Celsius.
- Density of Paulownia species @10% moisture content ranges from 17.8 to 23.2 depending on Variety and growing conditions.
- Thermal conductivity of Paulownia is very low thus giving it excellent heat/cool insulation properties.
- Chemical composition of Paulownia Varieties: Hemicellulose Pentozan 22 to 25%. Cellulose 46 to 49%. Lignin 21 to 23% Water 7 to 8% Ash .50 to 1.1% Fiber 58.5 to 60.1%
