Early Bird Nursery Paulownia Logo Early Bird Nursery
Specializing in Paulownia since 1989
TN Certificate# 14140

Properties of Paulownia Wood

Paulownia Wood as Presented by Dr. R. C. Tang at 1996 American Paulownia Association Auburn University.

Unique Characteristics

  • Light weight: Oven-dry specific gravity: 0.17 - 0.37
  • Very easy to dry and less drying defects
  • Very stable in wet/humid environments after being dried(i.e. very low/slow moisture absorption)
  • Highly durable/decay resistance under non-ground contact conditions
  • High fire resistance: Ignition Temperature: app. 425°C (ave. softwood 257°C, ave. hardwood:233°C)
  • High abrasion resistance: slow-wear against sand/soil
  • Soft, but has strength
    • low compression|| to grain strength: 2,800- 3,600 psi
    • good tensile || to grain strength: 5,300 - 8,500 psi
    • Loblolly pine: 8,060 - 10,670 psi
    • Eastern W. Pine: 10,600 psi
  • Excellent sound quality and absorption, less affected by change of weather
    • Excellent ,material for making high quality musical instruments
  • Porosity: 75 - 885
    • Loblolly pine: 62%
    • Aspen: 73%
    • Yellow Poplar: 71%

Density


Density of Light Weight Species

Species Condition Density (pcf (gr/cm3))
P. tomentosa (USA)

OD

10% MC

17.11 (0.274)

 

P. tomentosa

(New Zealand)

OD

AD

18.73 (0.300)

21.23 (0.340)

P. tomentosa

(Korean)

AD 14.98 (0.2400)

P. tomentosa

(China)

AD 20.41 (0.3270
P. kawakamii

OD

Green

15.55 (0.249)

20.23 (0.324)

P. fortunei AD 19.29 (0.309)
Western red cedar 12% MC

19.98 (0.320)

Balsa 9% MC 8.12 (0.130)

Shrinkage Coefficient

Shrinkage Coefficient(%) of Light Weight Species
Species *Specific Gravity Radial Tangential
Cottonwood 0.34 3.0 7.0
NW Cedar 0.31 2.2 4.9
E. W. Pine 0.35 2.1 6.1
Redwood 0.35-0.40 2.2 4.9
Paulownia 0.21-0.27 1.1-2.8 2.1-4.9

* Based on OD weight & 12% MC volume


Absorption Properties

Absorption Properties of Paulownia Wood

Water Absorption (%) Moisture Absorptions (%)*
1-Day 2-Day 40-Day 1-Day 2-Day 40-Day
84 108 253 12 15 19

*OD condition to conditions of 92% RH at 20°C

Species Bound Water Free Water
  24 hr fsp (days) % days
Paulownia 17.8 25.8 (7.5) 148 48
Willow 15.2 28.5 (28) 116 53
Red Pine 12.6 24.8 (24) 189 44

Durability

Durability of Paulownia (tomentosa)Tang 2984

Test Conditions  
1. Constant 65% RH at75°f  
2. Accelerated aging: 4-hr at 106 ± 2°C,Then
  4-hr water soaking, and followed by a
  16-hr under 26°F, repeated 30 days
  reconditioned to 10% MC, and then destructively
 

testing in bending

 

  Strength (MOR) Stiffness (MOE x 10 (to 6 power) psi)
  1" x 2" x 30" 1" x 1" x 16" 1' x2" x 30" 1' x 1' 16"
Test 1 5740 6260 0.758 0.641
Test 2 5420 6010 0.735 0.642
  • Change of strength and stiffness due to aging was insignificant
  • No visual splits, checks or severe twisting and bowing were observed after aging
  • Color was slightly darkened

Thermal Conductivity

Thermal Conductivity Coefficient of (10% MC)
  Radial Tangential Longitudinal
Paulownia 0.0645-0.0829 0.0584-0.0775 0.133-0.155
Sweetgum 0.136 0.121 --------------
Elm 0.143 0.143 --------------
Data sources: Hunan Agriculture College, PRC & USDA

Fiber Properties


Paulownia Fiber Properties
Species Length (mm) Width (µ) L/W Ratio

P. kawakamii

(Taiwan, mature tree)

1.208 20.7 58.4

P. tomentosa

USA, 6 year old tree OD condition

0.970 32.7 29.7

Data Sources: TFRI 1979, & Tang 1980

1 µ = 0.001 mm

     

Bending Properties


Bending Properties of Light Species (at 12% MC)
Species Strength:: MOR (psi) Stiffness: MOE x 10 (6 power) psi
Cottonwood 6820 1.102
N. W. Cedar 6530 0.798
Ponderosa Pine 9430 1.291
Redwood 7830 1.102
Balsa 2800 0.550
Paulownia    
tomentosa 5740 0.758
kawakamii 7020 1.200
fortunei 5700 0.867
Data Sources: Tang, Taiwan Forest Research Institute (TFRI), Sichuan Forest Science Research Institute (SFSRI), Others: FPL-USDA/FS

Mechanical Properties


Mechanical Properties of Paulownia Wood
  Fortunei* Kawakamii**

Bending

Modulus of Rupture

MOR (10 (6 power)psi)

5760 7020

Modulus of Elasticity:

MOE (10(6 power))

0.867 1200

Compression psi (||)

perpendicular

2800

300

3570

440

Shear (||) 800 1150

*SFSRI, PRC

**TFRI, ROC

   

Relative Working Properties


Relative Working Properties
Species Machining

Resistance to splitting in Nailing

Resistance to splitting in Screwing Nail& Screw Holding Ability Adhesive Bonding

S. Pines

Good Fair - Poor Fair   Very Good
Sweetgum Good Fair Fair Fair Excellent

Yellow Poplar

Very Good Excellent Good Fair Excellent
Cottonwood Good Excellent Excellent Fair Excellent
Paulownia Very Good Excellent Excellent Fair Excellent
Data Sources: USDA, TRFI, & Tang        
           

Flake board


Paulownia Flakeboard
Tang 1984
Density (pcf) MC (%) Strength MOR (psi) Stiffness: MOE x 10 (6 power) psi
19.5 8.3 1260 0.19
28.9 8.0 3540 0.98
P.wood (18.5) 12 5740 0.76
Sweetgum flakeboard (45) 8.7 7700 1.26

Out Look

Outlook of Pauolwnia's Utilization

  1. Fast growing species for short pulp fiber supply
  2. Flakeboard, particle board, OSB, or missed with high density species for ceiling, wall & roof panel
    1. reduce weight
    2. improve dimensional stability
    3. improve insulating performance
  3. Solid wood: wall panels, sidings, picture frames
  4. For shipping industries: pallets, crates, boxes & fiber-glass overlaid or metal sheets overlaid container
  5. Low cost and high quality activated charcoal for water pollution use
  6. Sale high grade logs to Japan
  7. Core material for laminated boards/panels
  8. Hair tonics: hair growth and restore hair color
  9. Shampoo contains ingredients of Paulownia extractives
  10. Medicine?