The CIOL product is handled like standard pressure-treated wood, but it uses a mixture of sorbitol, citric acid, and water instead of the traditional copper-based green treatment. To allow the chemicals to form a matrix within the wood structure, the wood samples must be heated at 140°C for 9 hours.
When impregnating, the CIOL product is processed similarly to standard pressure-treated wood, using a formulation of sorbitol, citric acid, and water in place of conventional copper-based treatments. To enable the chemicals to create a matrix within the wood structure, the wood samples must be heated to 140°C for 9 hours.
When impregnating Norwegian pine, which consists of a mix of heartwood and sapwood, the sapwood can be effectively treated, while the heartwood absorbs the treatment to a much lesser extent. Additionally, the CIOL treatment causes the sapwood to expand in volume by 10-15%, leading to variations in dimensions. To restore the wood to the desired dimensional stability, machine planing is normally required after treatment.
The highly protected shavings produced during the machine planing process are collected and either sold or further refined separately. izers, addressing both technological and environmental barriers.
Impregnation vacuum/pressure process
Curing at 140°C for 9 hours, 10-20% bulking (Larnøy et al. 2018)
Planing of treated boards
Fibers/particles can be re-used in wood-based panels
Pilot testing at NIBIO Ås
Demonstration plant and production of CIOL® at NIBIO. Impregnation vessel 6 m long x 0,8 m diameter. Photo: Erik Larnøy.
Demonstration plant and production of CIOL® at NIBIO. Impregnation vessel 6 m long x 0,8m diameter. Photo: Erik Larnøy.
Curing oven installed for post treatment to the right. Photo: Erik Larnøy.
Pilot production in autoclave. Photo: Erik Larnøy.
Upscaling for industrial size production at Moelven Østerdalsbruket AS
Autoclave at Moelven Østerdalsbruket AS before refurbishing. Photo: Erik Larnøy.
Welding the autoclave. The diameter is 1,8 meters inside. Photo: Erik Larnøy.
The autoclave after refurbishing vacum pumps, ventils and tube. Photo: Erik Larnøy.
Finished proof of concept batch, produced at NIBIO and planed at Moelven Østerdalsbruket. Photo: Erik Larnøy.
Research towards commercialization
NIBIO’s Department of Wood Technology is continuously working to bring CIOL® to the market. Testing includes material properties, areas of use, and process optimization towards commercialization.
ARD Innovation and NIBIO are collaborating on the Polysorb project, a commercialization initiative funded by the FORNY program at The Research Council of Norway. The project runs from 2022 to 2024. By the end of this period, we will start full-scale production with our first customer and optimize the chemistry for different applications and wood products. We will also initiate full-scale share offerings and commercial negotiations with potential customers to secure commercial contracts.
The goal of the Polysorb project was to document the use of CIOL® wood for cladding and terrace boards, as well as high-demand installation materials such as poles and structural elements. Eventually, we aim to bring this product to the market.
The process of treating wood with sorbitol and citric acid has been known since 1938. In 2018, an article first explored the polymerization of citric acid and sorbitol. However, no one has yet professionalized and industrialized the process to make the product available to consumers. After years of studies and testing, we finally have a product that is soon ready for commercialization.
Lab testing
Erik Larnøy in lab. Photo: Andreas Treu.
Testing different CIOL® mixtures. Photo: Erik Larnøy.
Finished CIOL® batch in lab before planing. Photo: Erik Larnøy.
Planing and preparing CIOL® treated wood for different purposes. Photo: Erik Larnøy..
Erik Larnøy inspects marine tested CIOL®. Photo: Andreas Treu.
Marine testing of CIOL®. Photo: Andreas Treu.
Research publications
Larnøy, E, Karaca, A, Gobakken, L. R., & Hill, C. A. S. (2018). Polyesterification of wood using sorbitol and citric acid under aqueous conditions. International Wood Products Journal, 9(2), 66–73.
Treu A, Nunes L, Larnøy E. Macrobiological Degradation of Esterified Wood with Sorbitol and Citric Acid. Forests. 2020; 11(7):776
Beck G. Leachability and Decay Resistance of Wood Polyesterified with Sorbitol and Citric Acid. Forests. 2020; 11(6):650.
Research projects
Norwegian Research Counsil / BIONÆR-Bionæringsprogram Increased valorisation of domestic timber by a novel wood modification system Project periode: 2020 – 2022
Norwegian Research Counsil / FORNY20-FORNY2020 PolySorb – verification, industrialization and commercialization Project periode: 2020 – 2022
Norwegian Research Counsil / FORNY20-FORNY2020 CIOL – product expansion towards a larger market Project periode: 2023 – 2025
Norwegian Research Counsil / BIONÆR-Bionæringsprogram CIOL – sustainable impregnation for the future Project periode: 2022 – 2025
Research publications
Larnøy, E, Karaca, A, Gobakken, L. R., & Hill, C. A. S. (2018). Polyesterification of wood using sorbitol and citric acid under aqueous conditions. International Wood Products Journal, 9(2), 66–73.
Treu A, Nunes L, Larnøy E. Macrobiological Degradation of Esterified Wood with Sorbitol and Citric Acid. Forests. 2020; 11(7):776
Beck G. Leachability and Decay Resistance of Wood Polyesterified with Sorbitol and Citric Acid. Forests. 2020; 11(6):650.
Research projects
Norwegian Research Counsil / BIONÆR-Bionæringsprogram Increased valorisation of domestic timber by a novel wood modification system Project periode: 2020 – 2022
Norwegian Research Counsil / FORNY20-FORNY2020 PolySorb – verification, industrialization and commercialization Project periode: 2020 – 2022
Norwegian Research Counsil / FORNY20-FORNY2020 CIOL – product expansion towards a larger market Project periode: 2023 – 2025
Norwegian Research Counsil / BIONÆR-Bionæringsprogram CIOL – sustainable impregnation for the future Project periode: 2022 – 2025
