Kebony and Thermory are the two most prominent thermally modified wood brands in North American markets. Both deliver Class I–II rot resistance without chemical preservatives. Both are FSC-certified. But they are not the same product.
The Core Process Difference
Thermory: pure heat at 185–215°C in steam or inert gas, no chemical additions. Kebony: combines thermal modification with furfuryl alcohol impregnation — a bio-based compound from agricultural waste (sugarcane bagasse, corn cobs) polymerized within cell walls during heat curing. Technically Kebony is "chemically modified" wood using bio-based chemistry — the key distinction for food garden growers wanting to avoid all chemical additions.
Species and Product Lines
Thermory: Scots pine (most available), ash (premium — hard and figured), poplar/alder for protected applications, across multiple modification levels. Kebony: radiata pine from FSC-certified plantations in Chile and Colombia, in two grades — "Kebony Character" (natural variation) and "Kebony Clear" (defect-limited premium). Simpler to specify than Thermory's range.
Performance and Pricing in 2026
Durability: Kebony achieves consistent Class I. Thermory's higher modification levels achieve Class I–II; lower modification levels are Class II. Janka hardness: Kebony-treated pine ~800–1,000 lbf (specific gravity increases from ~0.45 to ~0.60 after treatment). Thermory ash retains ~1,100–1,200 lbf (natural ash is 1,320 lbf, reduced ~15% by treatment). Thermory ash is the harder surface for wear-resistance applications. Pricing: Kebony decking $8–$14/lf (Character vs. Clear grade). Thermory pine $6–$10/lf. Thermory ash $9–$14/lf. At the lower end, Thermory pine is the most accessible entry point. See our full thermally modified guide for current sourcing.
Which to Choose
Kebony: best when consistent Class I durability matters or simple specification is preferred. Thermory: best when you want pure heat treatment, ash's hardness and figure, or lower entry price. For raised beds: Thermory pine at mid-modification levels is the best value — adequate durability, no chemical additions, FSC-certified. For decking needing maximum dimensional stability, Kebony's furfurylation advantage is real. Full comparison at our premium outdoor lumber guide.
Frequently Asked Questions
- Is Kebony's furfuryl alcohol safe for food gardens?
- Kebony testing shows furfuryl alcohol below regulatory detection limits in finished wood; the compound polymerizes within cell walls and is not in free form. For maximum precaution, Thermory's pure heat treatment is the simpler choice.
- How do these brands compare to ipe in actual durability?
- Ipe (Class I, 3,510 lbf Janka, 40–75+ year lifespan) outperforms both in absolute terms. Kebony and Thermory target 25–35 year lifespans at lower prices from more sustainable supply chains.
- Can I install either brand as a DIYer?
- Yes — both work with carbide-tipped blades and bits, harder than untreated pine but significantly easier than ipe. Pre-drill for fasteners; stainless steel or coated screws work well.
- Does either brand weather to gray if untreated?
- Yes — both silver-gray over time without UV protection. Annual penetrating oil maintains brown color; third-party teak or decking oils work as well as brand-name products.
- Are there domestic thermally modified alternatives?
- Yes — Arbor Wood (Minnesota) and other emerging producers process North American species with shorter supply chains. Quality benchmarking is less rigorous than European brands but the category is improving rapidly.