Balsa wood has enjoyed a longstanding reputation for its remarkable lightweight characteristics and user-friendly qualities in diverse applications. Yet, both enthusiasts and professionals often ponder whether balsa wood possesses the requisite strength for their particular projects.
After a comprehensive examination, delving into the structural attributes of balsa wood, scrutinizing its strength, constraints, and prospective applications, here are my insights to empower you with the knowledge needed to make informed choices for your upcoming projects.
About Balsa Wood
Balsa wood (Ochroma pyramidale), a fast-growing tropical hardwood native to Central and South America, is known for its lightness, low density, has more weight, and strength.
Popular in model making, insulation, and lightweight construction, its straight grain, easy workability, and buoyancy make it a versatile choice for hobbyists and professionals alike.
Below are some of Balsa tree wood’s properties:
|Elastic Modulus:||538,000 lbf/in2 (3.71 GPa)|
|Tree Size:||60-90 feet (18-28m) tall, 3-4 feet (1-1.2m) trunk diameter|
|Common uses are||Used in packing materials, wood artwork like making model planes, and curving|
|Color||White/off-white, yellow, pale straw, light brown|
|Tree growing time||4-8 years|
|Maximum Crushing Strength||4.9- 17.6|
|Density||Around 160 kg/m3|
|Toughness||Low – up to 15 Nm|
|Janka Hardness||67 lbF (300 N)|
Strength and Tensile Strength of Balsa Wood
While balsa woods are classified as a hardwood, it exhibits lower strength than many other hardwoods and softwoods. Nevertheless, its inherent strength is suitable for numerous woodworking endeavors.
The robustness of balsa wood is influenced by specific factors such as density. So, here are the respective values to comprehensively understand how strong balsa wood is.
|Hardness||67 lbf (300 N)|
|Bending strength||2,550 psi – 3,170 psi (370 ksi – 460 ksi)|
|Compressive strength||145 psi (1.00 Mpa)|
Balsa wood has low compressive and bending strengths, resulting in reduced durability. Despite being one of the lightest woods, sandwich panels and their cellular structure improve their mechanical strength.
Balsa wood’s strength is remarkable for its heaviness, with increased compressive strength in the middle area.
Where Balsa Trees Grow
Balsa wood has low compressive and bending strengths, affecting its durability. As the lightest wood, its mechanical properties are boosted by sandwich panels and a cellular structure that enhances strength.
Impressive for its heaviness, balsa wood’s compressive strength is weak laterally but increases significantly in the middle area.
What Is Balsa Wood Best Used For?
Balsa wood is known for its use in model airplanes and sandwich materials. It’s versatile, lightweight, and commercially valuable, lacking strength and durability.
With poor weight support, heat sensitivity, absorbency, and flammability, balsa wood is ideal for model-making but has limited woodworking applications.
How Heavy Can Balsa Wood Support?
Balsa wood, a lightweight and soft hardwood, is known for its ease of workability but has limitations in terms of strength.
It excels in applications like sandwich structures and model airplanes but is not suitable for weight-bearing tasks such as furniture or shelving. To enhance its strength, balsa wood can be reinforced using hardeners.
Is Balsa Wood Strong for Furniture?
Balsa wood, while lightweight and suitable for furniture, is primarily used in film production for breakaway props due to its minimal damage potential. Designers appreciate balsa wood for its sustainability, aesthetic appeal, and rapid growth.
The advantages of balsa wood furniture include its lightweight nature, suitability for model building, affordability, ease of handling, and strength from high water content. However, it is essential to consider balsa wood’s pros and cons.
Is Balsa Wood Strong Enough for Model Making?
Balsa wood’s lightweight nature and ease of cutting and shaping make it ideal for model making, offering a decent ratio of weight and strength. Common balsa wood models include:
Typically, these models are laminated with glass-reinforced plastic for added durability. Although balsa wood is often perceived as weak, its strength is sufficient for the shape to last a long time.
This ensures they aren’t subjected to excessive pressure or stress, as the material is soft, prone to breakage or cracking, and not much of a strong wood.
How About Carving?
Balsa wood is an excellent choice for carving, especially for beginners, as it boasts a remarkable softness that makes it easy to work with.
It allows for detailed carvings and sculpts, but simple designs are recommended due to strength limitations. Using sharp knife tools and materials can help prevent cracking.
How Hard Is Balsa Wood?
Although classified as a hardwood due to its cellulose structure, balsa wood is lighter, weaker, and the softest wood compared to most hardwoods and softwoods.
Its Janka Hardness scale test value, a measure of wood hardness based on resistance to wear and tear, is a mere 300, ranking it significantly lower than other durable wood types.
The Janka hardness test ratings of popular and good wood types help illustrate balsa wood’s strength compared to other varieties.
|Wood Species||Value of Janka Hardness|
|Balsa Wood||67 lbf (300 N)|
|White Cedar||320 lbf (1,423 N)|
|Red Cedar||350 lbf (1,557 N)|
|Sugar Pine||380 lbf (1,690 N)|
|Engelmann Spruce||390 lbf (1,735 N)|
|Redwood||420 lbf (1,868 N)|
|Silver Maple||700 lbf (3,100 N)|
|Douglas Fir||710 lbf (3,158 N)|
|Red Maple||950 lbf (4,200 N)|
|Black Cherry, Imbuia||950 lbf (4,200 N)|
|Cherry||995 lbf (4,430 N)|
|Black Walnut, North American Walnut||1,010 lbf (4,500 N)|
|Teak||1,155 lbf (5,140 N)|
|Yellow Birch / Baltic birch||1,260 lbf (5,600 N)|
|Red Oak (Northern)||1,290 lbf (5,700 N)|
|American Beech||1,300 lbf (5,800 N)|
|Ash (White)||1,320 lbf (5,900 N)|
|White Oak||1,360 lbf (6,000 N)|
|Hard Maple, Sugar Maple||1,450 lbf (6,400 N)|
|Hickory, Pecan, Satinwood||1,820 lbf (8,100 N)|
|Golden Teak||2,330 lbf (10,400 N)|
|Brazilian Cherry, Jatoba||2,350 lbf (10,500 N)|
|Red Mahogany, Turpentine||2,697 lbf (12,000 N)|
|Brazilian Walnut||3,684 lbf (16,390 N)|
Why Is it Considered a Hardwood When It’s Not Strong?
Contrary to popular belief, the classification of softwoods and hardwoods is not based on their physical properties but rather on factors such as seed production.
Balsa wood comes from angiosperm trees, which produce seeds enclosed in a shell. In contrast, softwoods like pine are gymnosperms , generating seeds without a protective shell.
How Quickly You Can Break Balsa Wood?
Balsa wood breaks easily, even with minimal force, making it unsuitable for crafting furniture. When assessing breakability, it is important to differentiate between sudden impact force and elasticity.
Balsa wood’s modulus of elasticity is 538,000 psi, compared to white oak’s 1,762,000 psi. In terms of force required to break the wood, balsa scores 2,840 lbf/in2, while the latter scores 14,830 lbf/in2.
Balsa wood will readily break under sudden force, such as striking it with a hammer. However, its elasticity is distinct from its strength in woodworking project applications.
Is It Expensive?
A sheet of balsa wood, measuring 3/16-inch in thickness, typically falls within the price range of approximately $10 per square foot. It’s worth noting that thicker sheets command higher prices.
Unlike most types of wood, balsa is commonly found in the form of manufactured plywood or veneers rather than solid blocks. This distinction in availability is essential for those considering its use in their projects.
Consequently, the price depends on the thickness of the balsa lumber being purchased. Thin sheets are also being sold for pounds per square inch.
Balsa Wood vs Basswood
Basswood is stronger than balsa wood, though balsa wood boasts a superior and better strength-to-weight ratio. Balsa wood’s lightweight nature makes it ideal for model airplane and boat construction and carving.
The compressive and bending strengths of both basswood and balsa wood can be compared through specific measurements.
|Type of Wood||Compressive Strength||Bending Strength|
|Basswood||4, 730 psi||8, 700 psi|
|Balsa wood||145 psi||2,550 psi – 3,170 psi|
Balsa wood, while not the absolute pinnacle of strength in the realm of woodworking, does exhibit a commendable level of durability. What truly sets it apart is its exceptional strength-to-weight ratio, making it an ideal choice for particular applications.
In scenarios that demand lightweight attributes, such as crafting model airplanes and intricate carvings, balsa wood’s distinctive properties shine brightly. It demonstrates its versatility and practicality, proving to be an invaluable asset when matched with the appropriate projects and materials.