What Is The Difference Between Hemlock and Pine Lumber (Strength Test)
In a controlled bending test, clear western hemlock averages about 11,300 psi in bending strength, compared with about 8,600 psi for eastern white pine. Hemlock is also slightly stiffer on average. These figures compare specific clear-wood species near 12% moisture content; they do not rank every pine board or set safe structural loads.
A common myth is that “pine” has one strength value and can be compared directly with hemlock by name alone. It cannot. Pine is a group of species, and their properties vary. Even two boards from the same species can differ because of knots, grain angle, moisture, and grade.
I teach people to separate two questions: how clear wood compares in a controlled test, and how a graded board performs in a real structure. The first helps explain material behavior. The second requires the right species, grade, design values, and code rules.
Species Identification, Test Setup & Safety Preparation
A fair comparison starts with the exact species and a consistent test plan. Here, “hemlock” means western hemlock (Tsuga heterophylla), and “pine” means eastern white pine (Pinus strobus). The test should compare similar clear specimens under matched conditions, not unrelated boards with different defects or moisture levels.
The word “pine” on a sales listing may not identify eastern white pine. Before testing, check the botanical species if known, along with the board’s grade and condition. If you cannot confirm the species, report that uncertainty rather than treating the result as a species-level comparison.
| Property | Western hemlock | Eastern white pine | What it tells you |
|---|---|---|---|
| Bending strength (MOR), clear wood near 12% moisture | About 11,300 psi | About 8,600 psi | Average stress at failure in bending |
| Stiffness (MOE), clear wood near 12% moisture | About 1.29 million psi | About 1.24 million psi | Resistance to bending while loaded |
| Janka hardness | About 500 lbf | About 380 lbf | Resistance to surface indentation |
MOR means modulus of rupture. It is a calculated measure linked to the stress at which a bending specimen fails. MOE means modulus of elasticity. It describes stiffness, or how much the specimen resists bending under load. Janka hardness measures indentation resistance; it is not a bending test.
In the published averages shown, hemlock’s MOR is about 2,700 psi higher, or roughly 31% above eastern white pine. Its MOE is about 50,000 psi higher, or roughly 4%. These are averages, not guaranteed results for an individual board.
Before testing, record each specimen’s dimensions, grain direction, visible defects, grade information, and actual moisture content. Use a calibrated test frame with supports and a load cell suitable for the specimen and expected load. Confirm that the specimen is aligned and that guarding is in place.
Controlled Bending Test and Field-Use Interpretation
A controlled bending test applies a measured load to a supported wood specimen and records how it bends and where it fails. ASTM D143 is used for small, clear specimens; ASTM D198 is used for structural-size lumber. Their results should not be treated as interchangeable because the specimens and test methods differ.
How to keep the comparison fair
For a valid comparison, hold the main test conditions steady. Use matched specimens and the same selected method, conditioning, grain orientation, span, loading arrangement, and loading rate. Follow the chosen ASTM procedure for specimen details and calculations rather than improvising dimensions or setup.
A careful sequence looks like this:
- Prepare and identify. Confirm the species as far as possible. Record the grade, dimensions, defects, grain direction, and moisture content. Inspect the frame, supports, load cell, and guard.
- Condition and set up. Bring both species to the same test condition. Use the appropriate ASTM method, span, and loading arrangement. Check calibration and specimen alignment.
- Load and document. Apply the load as the selected method directs. Keep people clear of the specimen’s likely fracture path. Record load, deflection, failure location and mode, and moisture content.
- Report and compare. State the test method, sample count, conditioning, and variation among specimens. Compare like with like, and do not present an average as a guaranteed board value.
The two ASTM methods answer related but distinct questions. D143 focuses on small, clear wood samples that limit the effect of natural defects. D198 evaluates structural-size lumber, where size and real-world features matter. A D143 result should not be used as if it were a D198 result.
What the numbers mean in use
For a clear-wood comparison, the listed averages suggest that western hemlock has higher bending strength than eastern white pine. Their average stiffness figures are much closer. That distinction matters: a wood can have a higher average failure strength without being dramatically stiffer in ordinary bending.
Consider a homeowner choosing boards for a non-structural shelf. The table can help explain why the species may behave differently, but it cannot tell the homeowner how much weight a specific shelf can safely hold. Board dimensions, support spacing, grade, knots, fastening, and the load all affect that decision.
For a beam or other load-bearing part, do not size or substitute lumber using these clear-wood averages. Use applicable grade-specific design values and building-code requirements, or consult a qualified professional. The real board and its grade matter more than a general species comparison.
Measurement Checks, Failure Review & Data Quality
Good data depends on more than the peak load. Check that measurements are consistent, note where each specimen breaks, and review whether the failure happened in the intended test region. A single board can give a misleading result if a defect or a setup problem controls the break.
A knot, slope of grain, check, or other local defect can dominate failure. If one hemlock sample contains a large knot and one pine sample is clear, the result mainly compares those two pieces, not the species. This is why matched, defect-free samples are useful for a clear-wood comparison.
Record the actual dimensions and moisture content rather than relying on assumptions. Also note the test method, support span, load arrangement, loading rate, and number of specimens. Repeated samples help reveal variation; one test cannot show how much boards vary within a species.
Review the failure location after each test. A specimen that breaks at a grip or support, or outside the intended test area, may not provide a valid comparison under the selected method. Follow the method’s rules for deciding whether to retain or reject that result.
Useful records include:
- Species identification and grade details, if available
- Specimen dimensions and moisture content
- Visible defects and grain direction
- Test method, setup, and calibration status
- Load, deflection, failure location, and failure mode
- Number of specimens and spread of results
If the results differ sharply from the expected averages, check the species identification, conditioning, dimensions, setup, and defects before drawing a conclusion. The published values are reference averages, not pass-or-fail thresholds for individual samples.
Specimen Conditioning, Storage & Seasonal Moisture Effects
Wood moisture affects its measured properties, so both species should be tested at the same moisture condition. The reference values here are near 12% moisture content. That does not mean every board reaches or stays at 12%; actual moisture changes with storage and surrounding conditions.
A dry indoor board and a damp board may not produce a fair species comparison. Measure and report moisture content for each specimen, and condition the samples consistently before testing. Do not assume that two boards stored in the same room have identical moisture content.
Keep specimens protected from rain, standing water, and sudden changes in storage conditions before the test. Record how they were stored and conditioned. If the moisture readings differ, bring the specimens to a comparable condition using a controlled process, then measure again.
Moisture variation also helps explain why a field board may not match a published clear-wood average. Seasonal changes, exposure, and the board’s own history can affect its condition. A test report should make its moisture conditions clear so readers understand what the comparison does and does not show.
What the Strength Test Means for Real Boards
A clear-wood test isolates material behavior; a structural lumber decision considers the actual board, its grade, and its use. That difference is central to applying this comparison. A species average can explain a trend, but it cannot replace design values or a board inspection.
Example: comparing two sample boards. Suppose a person tests one clear hemlock specimen and one clear eastern white pine specimen at similar moisture content. If the hemlock specimen reaches a higher MOR, that is consistent with the published averages. It still does not prove that every hemlock board is stronger than every pine board.
Example: choosing lumber for a repair. A repair may involve graded boards with knots and different dimensions. The appropriate comparison is between the grade-specific design values and requirements for that use, not between a structural board and small-clear test figures. If the “pine” species is unknown, the label alone is not enough to choose a substitute.
Example: an unexpected break. If a test specimen breaks at a knot, the result may reflect that knot more than the average clear-wood property. If it breaks at a support, the setup may have affected the result. Review the failure mode before using the number.
These examples show how the test applies in practice without turning average values into promises. For structural work, use the relevant design information and code requirements.
Conclusion and FAQ
Western hemlock averages higher bending strength than eastern white pine in the stated clear-wood comparison, while their average stiffness values are fairly close. The result applies to those species and conditions, not to all lumber sold as pine. Identify the wood, control the test, and use grade-specific design values for structural decisions.
Is hemlock stronger than pine?
In the stated comparison, western hemlock has a higher average clear-wood MOR than eastern white pine: about 11,300 psi versus 8,600 psi near 12% moisture content. “Pine” includes many species, so this does not establish a ranking for every pine board.
Which is stiffer, hemlock or eastern white pine?
Western hemlock has a slightly higher published average MOE in this comparison: about 1.29 million psi versus 1.24 million psi for eastern white pine. MOE measures stiffness, not the load a particular board can safely carry.
What does MOR mean in a lumber test?
MOR, or modulus of rupture, is a calculated measure related to the stress at which a wood specimen fails in bending. It is useful for comparing test results under stated conditions, but it is not an allowable design value for a graded board.
What does MOE measure?
MOE, or modulus of elasticity, describes a material’s stiffness under load. In a bending test, it relates to how much the specimen deflects as load is applied. A higher MOE does not by itself establish safe capacity.
Does Janka hardness show bending strength?
No. Janka hardness measures how much force is needed to press a steel ball into wood. It describes resistance to indentation, not bending strength. The listed values are about 500 lbf for western hemlock and 380 lbf for eastern white pine.
Can I use these averages to size a beam?
No. Clear-wood averages are not structural design values. Beam sizing depends on species, grade, dimensions, span, loading, and code rules. Use applicable grade-specific design information or seek qualified help for a structural decision.
Is “pine” one specific wood species?
No. Pine is a common name used for multiple species. A comparison should identify the actual species, such as eastern white pine, rather than assume that all lumber sold as pine shares the same properties.
Which ASTM method applies to a bending test?
ASTM D143 is used for small, clear specimens. ASTM D198 is used for structural-size lumber. The methods use different specimen types and procedures, so results from one should not be treated as directly equivalent to results from the other.
Why might a board test weaker than the published average?
A board may differ because of species, moisture content, knots, slope of grain, checks, or other defects. Test setup and specimen dimensions also matter. Published figures are averages, not guaranteed minimums for individual boards.
What should I record during a comparison test?
Record the species, dimensions, grade or defect status, grain direction, and actual moisture content. Also report the test method, setup, sample count, load, deflection, and failure location and mode. These details make the result easier to interpret.
(This article was written by one of our staff writers, Evan Bradley. Visit our Meet the Team page.)
