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Empress Lumber

Beautiful and sustainable eco-timber

Properties and Specification

Empress Splendor tree 

Common Name(s):

Paulownia, Empress Splendor, Empress, Kiri

Scientific Name:

Paulownia Elongata, Paulownia Fortunei 

Distribution:

Native to eastern Asia with the oldest fossils discovered in North America

Tree Size:

30-65 ft (10-20 m) tall, 2-4 ft (.6-1.2 m) trunk diameter

Color/Appearance:

Heartwood typically a pale brown, sometimes with a reddish or purplish hue. Pale white sapwood not clearly demarcated from heartwood.

Rot Resistance:

Reported to be durable regarding decay resistance and decent weathering characteristics.

Workability:

Given its straight grain and lightweight, Paulownia is extremely easy to work. Takes a wide variety of glues, stains, and finishes well.

Odor:

No characteristic odor.

Allergies/Toxicity:

Besides the standard health risks associated with any type of wood dust, no further health reactions have been associated with Paulownia.

Common Uses:

Plywood, veneer, furniture, boxes, millwork/siding, musical instruments (electric guitar bodies), clogs, carvings, watercraft, and other specialty items.

Lumber Properties 

  • Empress wood is about 2/3 the weight of the lightest commercial wood grown in the US. 
  • It weighs an average of 14 to 19 lbs per cubic foot. 
  • It is almost 1/3 the weight of Oak (44 lbs p/cubic ft) and half the weight of Pine (30 lbs p/cubic ft).
  • It has one of the highest strength to weight ratios of any wood.
  • Empress wood 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 – 1/32 inch thickness.
  • Intricate patterns can be cut with a jig saw or band saw without splitting easily and has been a favorite for many carvers in the US.
  • Furniture, doors, and windows can be made with close tolerances.
  • All normal finishing materials can be applied and it bonds well with glue.
  • Air-drying takes as little as 30 days.  Boards can be kiln dried at high temperatures in as little as hours to 10% moisture content with no warping.
  • Reported shrinkage from green to oven-dry is only 2.2% radial and 4.0% tangential.  It 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, as well as more fire resistant due to the moisture content of the tree during growth. 
  • Empress log homes are said to have twice the R factor as pine or oak logs and are a very good insulator.
  • This temperature resistance also serves to give the wood a high fire resistance.
  • Ignition temperature for Empress Wood is approximately 420 – 430 degrees Celsius (Other hardwoods ignite at 220-225 degrees Celsius).

Technical specification

Density

Density @10% moisture content: 14.37 – 18.75 lbs/cuft 
Density @10% moisture content: 18.17 lbs/cuft 
Density @ oven dried: 17.11 lbs/cuft 

Chemical Composition

Alpha-Cellulose content: 40.72%; 38.50%-41.46%
Pentosan: 24.78%; 20.56%-25.35% 
Lignin content: 20.87%; 21.24%-24.28%
Leaves: ursolic acid, C30H4803; matteucinol, C18H1805
Xylem: Paulownium, C20H18O7@CH3OH; d-Sesamin
Bark: syringin, C17H24O9@H2O; Catapinoside

Bending & Compression Properties

Modulus of rupture (mor): 5420-5740 psi
Modulus of elasticity (moe) x 10 to 6th: 0.735-0.758 psi
Compression parallel to grain: 2800-3560 psi 
Compression perpendicular to grain: 300-440 psi 
Shear parallel to grain: 800-1150 psi

BTU (British thermal unit) 

7600-8400 per pound 

Hardness

Janka Hardness Scale: 260-290
Shrinkage Coefficient (%)
Specific gravity: 0.251 – 0.274 (23 to 30% of the density of water)
Specific gravity @ 10% MC: 0.265 
Radial: 1.1 – 2.7
Tangential: 2.1 – 4.9
Green to Oven Dry: 5.9

Moisture Absorption 

(92% Relative Humidity @ 20 degrees C)
1-day; 2-day; maximum 
12%; 15%; 19%

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