Kebony and Thermory are modified real-wood products designed to improve durability and dimensional stability. Both offer alternatives to conventional timber for decking, cladding, and selected architectural applications.
The main difference is the modification process: Kebony uses furfurylation, while Thermory uses controlled heat and steam. Their appearance, performance, installation requirements, and warranties also vary by product.
Neither brand is automatically the better choice. A useful comparison starts with the exact boards you are considering—not just the names on the quotation.
What Is Kebony Wood?
Kebony is solid wood enhanced through a modification process called furfurylation.
The process introduces a furfuryl-alcohol-based solution into the timber, followed by treatment that polymerizes it within the wood. This changes how the material responds to moisture and improves properties such as durability and hardness.
Kebony is modified timber rather than a plastic–wood composite or a layered plywood product.
Its product ranges include Kebony Clear, selected for a cleaner appearance, and Kebony Character, which features more visible knots. Availability and board profiles depend on the market.
Fresh Kebony typically has a brown appearance. When exposed outdoors without a color-preserving finish, it develops a silver-gray surface.
What Is Thermory Wood?
Thermory produces thermally modified real wood. Its modification process uses controlled heat and steam to change the wood’s properties and reduce its tendency to absorb moisture.
The process does not simply “burn off cellulose.” It changes the wood under controlled conditions, with treatment adjusted for the species and intended application.
Thermory offers several species and product lines, including ash, pine, and spruce. These have different grain patterns, knot characteristics, and performance specifications.
Therefore, describing all Thermory as knot-free would be inaccurate. Thermo-ash can provide a relatively clean appearance, while thermo-pine commonly features visible knots.
Kebony vs Thermory: Quick Comparison
| Feature | Kebony | Thermory |
|---|---|---|
| Material | Modified real wood | Modified real wood |
| Modification method | Furfurylation | Controlled heat and steam |
| Product choices | Clear and Character ranges, depending on market | Multiple species and collections |
| Initial appearance | Typically brown | Brown tones varying by species and treatment |
| Natural outdoor weathering | Develops a silver-gray surface | Develops a silver-gray surface |
| Main applications | Decking, cladding, and selected millwork | Decking, cladding, and selected flooring and interior products |
| Maintenance | Cleaning; suitable coatings if retaining color | Cleaning; suitable coatings according to product and appearance goals |
| Hardness | Product-specific | Species- and product-specific |
| Warranty | Depends on product, application, and market | Depends on species, product, and market |
| Price | Requires a local project quotation | Requires a local project quotation |
1. Durability and Outdoor Performance
Both brands offer products intended for exterior use. Modification improves their resistance to decay compared with the corresponding unmodified timber.
However, durability does not mean immunity to every outdoor problem. Surface weathering, dirt, algae, checking, and damage can still occur.
A deck also depends on its supporting structure, ventilation, drainage, and fasteners. Durable boards installed over a poorly draining substructure can still develop problems.
When comparing products, check:
- Whether the board is approved for decking or cladding.
- Required clearance and ventilation.
- Restrictions on ground contact or persistent wetting.
- Suitable fasteners and fixing methods.
- Maintenance requirements for the chosen finish.
Do not assume that an exterior cladding board is suitable for a walking surface.
2. Hardness and Resistance to Wear
Kebony’s published information lists Kebony Clear at approximately 1,619 lbf on the Janka hardness scale, with a density of approximately 670 kg/m³. These figures apply to that product, not automatically to every Kebony board. See the manufacturer’s Kebony technical FAQs.
Thermory cannot be represented accurately by a single hardness figure because its range includes different species and treatments.
For decking, hardness is useful, but it is only one consideration. Surface texture, splintering, wet slip performance, board thickness, and installation also matter.
Ask for test information for the exact Thermory and Kebony products being quoted. Avoid comparing modified wood with a hardness value for its untreated parent species.
3. Appearance and Grain
Kebony
The Kebony Clear suits projects where a comparatively uniform, low-knot appearance is preferred. Kebony Character provides a more visibly knotty look.
Both can work well in contemporary or traditional designs, depending on board dimensions and layout.
Thermory
Thermory offers a broader species-based choice. Ash, pine, and spruce have different grain patterns and visual character.
This can be helpful when coordinating decking with cladding or interior surfaces. However, different species should not be expected to weather identically.
For either brand, request several samples rather than choosing from one small piece or a photograph.
4. Color Changes and Maintenance
Both Kebony and Thermory change color outdoors. Uncoated exposed surfaces generally move toward silver-gray as they weather.
This is not automatically evidence of rot or product failure.
The practical maintenance decision is whether you want to:
- Allow natural weathering.
- Preserve a brown appearance.
- Use a specific factory or site-applied finish.
Maintaining brown tones usually requires an appropriate pigmented, UV-protective coating and periodic renewal. Exposure, climate, and coating choice affect the schedule.
Even a naturally weathered deck needs cleaning. Remove leaves and debris, keep drainage gaps open, and follow the manufacturer’s cleaning instructions. Do not assume aggressive pressure washing is acceptable.
5. Installation and Workability
Both materials can be worked with woodworking tools, but they have product-specific installation requirements.
Modified boards need careful handling, especially around thin edges, ends, and fixing points. Use the specified drilling, fastening, and spacing procedures.
Some products offer concealed fixing systems or end-matched profiles. These can affect appearance, installation time, and waste, but they are not interchangeable between brands.
For example, an end-matched board does not automatically allow unsupported joints. Follow the instructions for that exact profile and system.
Also distinguish decking boards from structural members. Neither brand name alone establishes suitability for joists, beams, or other load-bearing components.
6. Warranty: Compare the Details
A long warranty can be valuable, but the headline number does not describe every condition.
Kebony Clear’s US decking information advertises a 30-year residential warranty against rot. Other Kebony products or applications may have different terms.
Thermory USA’s published limited warranty lists 20 years for Scots pine and radiata pine, and 25 years for ash, red oak, and spruce, subject to its conditions. The Thermory USA warranty document also includes registration requirements, exclusions, and limits on remedies.
Before ordering, confirm:
- Which warranty applies to your location and product.
- Whether registration is required.
- What types of decay or defects are covered.
- Whether normal weathering and appearance changes are excluded.
- Whether removal and installation labor are covered.
- Whether compensation reduces over time.
A durability classification, an estimated service life, and a written warranty are three different things.
7. Which Is More Expensive?
There is no dependable rule that Kebony always costs more than Thermory.
Thermory ash, pine, and spruce may have different prices. Kebony ranges, dimensions, and profiles also affect the quotation.
Compare the installed cost, including:
- Boards and usable coverage.
- Clips, screws, and accessories.
- Substructure requirements.
- Delivery and waste allowance.
- Labor.
- Initial finishing and future maintenance.
A lower board price may not produce a lower project cost if installation is slower or more material is wasted.
8. Sustainability and Material Claims
Both brands position modified wood as an alternative to other exterior materials. Responsible timber sourcing and a useful service life can support that argument.
However, neither should be described as “100% environmentally friendly.” Production, transport, coatings, maintenance, and end-of-life handling all have impacts.
Ask for the sourcing certification and environmental documentation relevant to the product you are purchasing.
Thermory’s heat-and-steam process and Kebony’s furfurylation process are different approaches. That difference alone does not establish which finished product has the lower overall environmental impact.
Kebony Advantages and Disadvantages
| Advantages | Limitations |
|---|---|
| Clear and Character appearance options | Initial brown color changes outdoors without suitable protection |
| Published technical information for specific products | Performance figures cannot be generalized across the whole range |
| Decking and cladding systems available | Installation details and approved accessories must be followed |
| Rot warranty available for qualifying products | Premium project cost and regional availability require checking |
Thermory Advantages and Disadvantages
| Advantages | Limitations |
|---|---|
| Several species and appearance options | Properties vary between species and product lines |
| Heat-and-steam modification | Careful handling and installation remain important |
| Decking, cladding, and selected interior ranges | Not every product is suitable for every application |
| Concealed fixing and end-matched options on selected products | Color retention requires an appropriate maintenance plan |
Which Is Better for Decking?
Both can be suitable when you choose a decking-rated product and install it correctly.
Consider Kebony Clear when its appearance, board profile, technical data, and local installation system suit your project.
Consider Thermory when you want to choose between species, grain patterns, or particular decking profiles and fixing systems.
For a barefoot area, also assess the actual surface finish, expected sun exposure, and maintenance needs. No wood deck should be assumed permanently splinter-free, cool, or slip-proof.
Which Is Better for Cladding?
For cladding, appearance, fixing details, ventilation, and weathering often carry more weight than indentation hardness.
Compare full-size samples where possible. Check how corners, window openings, board ends, and transitions will be finished.
Fire performance and wind resistance must be verified for the specific product and assembly where required. A general durability claim does not establish those properties.
Kebony vs Thermory: Which Should You Choose?
Choose between specific products rather than declaring one brand universally better.
Start with the intended application, compare samples and technical documents, then obtain complete installed quotations. Pay particular attention to the appearance you want after several years—not just on installation day.
Both brands can provide attractive modified-wood surfaces. The better choice is the product whose specification, installation requirements, maintenance plan, and local support fit your project.