Hiili (Carbon)
Hiili is the bold, black classic of the Hiil range. Shaped by fire, its deeply textured grain symbolises transformation and resilience.
Applications
Manufacturing
Hiili product is made by charring the wood surface at over 1000 °C using Hiil’s charring technology. After charring, the product is quenched with water, dried and oiled with clear special linseed oil. The oil alters the char surface structure and binds the carbon into the wood.
Specifications
| Surface | Charred, oiled |
|---|---|
| Wood species | Pine, Kiertopuu® pine |
| Wood certification | PEFC certified |
| Standard sizes | |
| Panel | 27 mm Widths 118, 143, 193 mm Lengths 4110, 5030 mm, end-matched Exterior / interior cladding Coverage −10 mm from the width  |
| Board | 27 mm Widths 118, 143, 168, 193 mm Lengths 4200, 5100 mm Exterior / interior cladding  |
| Country of origin | Finland |
| CE marking | Product is CE marked |
| Fire class | D class C-class indicative. B-class with fire retardant indicative. |
Indicative lead time for the standard range is about 5 weeks from order. Check availability for each product.
Outside the standard range, products can be made to order in thicknesses 20–43 mm, widths 93–193 mm and lengths 2000–6000 mm. Price and lead time are quoted case by case.
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Weather exposure
Weather exposure test for Hiil Oy charred wood products
Natural Resources Institute Finland - 27 March 2025 results - Veikko Möttönen and Nina Pottonen.
Weather exposure test programme: 102 min UV exposure and 18 min UV+rain exposure, repeated over 6 weeks (1008 h). Equivalence: The treatment can be considered to correspond to approximately 3 years of outdoor exposure to rain and sunlight. UV radiation dose in the test was approximately 218 MJ/m².
Installation and maintenance guides
Downloads
Find more on the Resources page.
Example projects using Hiili
Kuusijärvi saunas – exterior cladding and decks in charred wood
Public smoke saunas and service buildings at Kuusijärvi – charred cladding and Noki decks connect the new to an old ritual.
Charred exterior cladding for a wind farm visitor centre
Pahkakoski wind farm maintenance and visitor centre in Yli-Ii – light stone wood and charred wood create a recognisable facade.
Decks and interior surfaces in charred wood at a holiday home
At a holiday home in Kustavi, a Kuura ceiling, Hiili accent walls, Kelo decks and Noki benches continue from indoors into the archipelago landscape.
TRIB3 Helsinki Sture, charred wood building the atmosphere
TRIB3 Sture boutique fitness studio with charred wood – Hiili and Korppi at reception, Kuura in the Pilates room. A shared, community-led atmosphere and a clear material language.
Charred exterior cladding on archipelago rock
A detached house on archipelago shoreline – charred exterior cladding and oiled Hiili make the building a calm part of the landscape.
Halo Igloos Resort – Northern lights and charred wood
Halo Igloos is a glass igloo resort in Rovaniemi where Hiil Kiertopuu products bring an ecological dimension both outdoors and indoors.
Charred exterior cladding for a detached house carport
Charred wood cladding on a carport in a detached house setting – Finnish Hiili and Kiertopuu® in a clear architectural frame.
Charred exterior cladding for Tikkurila fire station
Tikkurila readiness station in Vantaa – a building by P&R Arkkitehdit with Hiili exterior cladding. A calm, recognisable expression.
Saunalautta Hiisi – Charred walls inside and out
Saunalautta Hiisi by the sea – charred wood on the exterior and inside. Necto Design Oy; Hiili stands up to sea wind and sauna moisture.
Sauna Panels and Roof in Charred Wood
A private home sauna with charred wood wall panels and ceiling in Hiili finish. Backrest from the same board material for durability.