Arbor Wood Co. has ordered a second thermal modification kiln from Jartek for its plant in St. Joe, Indiana. The new kiln has a working volume of 45 m³ (approx. 19,000 BF) per batch.
The order follows the first Jartek kiln delivered to St. Joe under an agreement announced in December 2024 — the first thermal modification kiln of its kind in the United States.
The second kiln connects to the existing thermal energy plant and control system installed with the first kiln, which was dimensioned from the outset to serve more than one modification chamber. This is a deliberate design principle in Jartek deliveries: a producer can begin with a single kiln and add capacity in steps, without rebuilding the surrounding infrastructure or moving operators into a new control environment.
"A second kiln is the strongest endorsement a technology supplier can receive," says Tuuli Luoranen, Chair of the Board at Jartek. "The first St. Joe kiln showed that the process runs reliably on North American hardwood and softwood species at industrial scale. The second one builds on the same energy plant and the same control platform, which is exactly how we design our installations — to grow with the producer, one kiln at a time."
Thermal modification uses only heat and steam — no chemicals — to improve the durability, dimensional stability and thermal performance of wood. Each wood species requires its own treatment recipe, and Jartek maintains a dedicated testing facility in Finland for developing and validating recipes for species that are new to industrial modification.
Jartek's thermal modification technology is fully compatible with the ThermoWood® process, and Jartek is the only technology supplier among the members of the International ThermoWood® Association (ITWA). Arbor Wood Co. joined the association in 2025 as the first U.S.-based permanent member, giving it the right to market its products under the ThermoWood® trademark.
"The first kiln has performed well and production is in good shape, which made the decision on a second one an easy one. As the first U.S. member of the International ThermoWood® Association, we're in a position to grow the domestic ThermoWood® supply, and this kiln does exactly that on infrastructure that has already proven itself here," says Jon Heyesen, CEO of Arbor Wood Co.
Read the reference story and watch the video about the first kiln >>
Photo: The first Jartek kiln at Arbor Wood Co.'s St. Joe plant. © Arbor Wood Co.