Thermally Modified Hardwood
All thermally modified wood products are designed for long-term use in commercial exterior applications, although they can also be applied indoors. Manufactured from hardwoods, typically Oak, Tournesol thermally modified wood is harvested in the Northeast. The wood is milled and thermally processed, naturally producing a deep, rich color. This color is unique to each piece of wood and each batch in the kiln and is subject to variation.
Our thermally modified wood is dimensionally stable and subject to minimal expansion or shrinking. In addition, the altered cell structure keeps the wood from absorbing moisture, which causes typical warping, twisting, cupping, and cracking. Adequate ventilation will help prevent water from being trapped on the surface.
Care & Maintenance
Like any natural wood product, thermally modified wood can show small stress cracks, referred to as “checking.” Surface cracks are due to the surface of the wood expanding and contracting at a different rate than the core, yet do not affect durability.
Thermally modified wood and all wood elements of our planters and site furnishings are treated with Penofin® oil before delivery. Tournesol recommends sealing boards with oils and sealants meant for hardwoods to maintain the rich color and minimize checking. For the first year after receiving the products, seal every six months (depending on your climate) and then once a year. While most sealing products will darken the wood slightly, some leave an undesirable surface color. Test any sealants or oils on an inconspicuous area prior to applying to the entire project. Also, lessen splitting or end-checking with an application of wax (Anchorseal ®) to the ends of the boards. Clean the wood before any application.
Cleaning
- We recommend using a commercial deck cleaning product that is effective against biological growth and mold spores. Again, test products on the wood in an inconspicuous location before applying them to the entire project.
- The wood will develop a natural patina as it ages, especially when left unsealed. The grain of any unsealed wood may naturally become more pronounced. Despite surface changes, the wood will remain strong and decay resistant for the project’s lifespan.
- The wood is treated with a light Penofin oil, and pressure washing is not recommended as it may cause surface damage to the wood.
Wood Color Changes Over Time
Each piece of thermally modified wood has its own unique color, shaped by the specific batch and kiln cycle—no two are exactly alike. Over time, all wood species naturally change color when exposed to UV light, gradually developing a silver-gray patina. Our products arrive with a UV-protectant oil to help slow this aging process, though it won’t stop it entirely. While the surface color evolves, the wood’s durability and resistance to decay remain unchanged. If desired, sanding can restore the original tone beneath the weathered surface.
Download the Care, Maintenance & Warranty Guide (PDF)
