Korppi (Raven)
Korppi combines the rugged texture of a charred surface with the mystical beauty of a glossy blue tint. Interior use only.
Applications
Manufacturing
Korppi 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 blue-tinted special linseed oil. The oil alters the char surface structure and binds the carbon into the wood.
Specifications
| Surface | Charred, oiled, tinted blue |
|---|---|
| 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  |
| 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 Korppi
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 wood panelling for an Aufguss sauna
Ikaalisten Spa’s Aufguss sauna with Hiil Korppi – a charred surface with a blue sheen that shifts with the light.