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December 2005 & January 2006 - The Logging and Sawmilling Journal



A Wood Preservation Alternative

The thermowood preservation method has been marketed as an environmentally friendly alternative to chemical use, but the process has now been further moved forward by an Ontario company with an advanced dryer design.

By Tony Kryzanowski


A Northern Ontario company has spent in excess of $1.2 million and put in four years of research and development to introduce a proven Finnish wood preservation technology to North America, a technology that uses extreme heat instead of chemicals. Called Superior Thermowood, the company has just recently commissioned its first “ecodryer” near Thunder Bay, making it the first producer of thermowood on this continent.

In addition to turning a profit for the company’s 32 private investors, company president and chief operating officer Arvo Tyrvainen says they hope the forest industry recognizes this process as one way to add value to commodity grade softwood and hardwood products, and a way to create forest industry jobs right here in Canada. “We believe that value-added processing should happen here,” says Tyrvainen, “and because it is a valueadded product being exported from Canada, our understanding is that Superior Thermowood will be exempt from softwood lumber duties.”

The company’s desire to create forestry-related employment in the region is well timed, as Northern Ontario has recently endured considerable job losses in the forest industry due to mill closures in such places as Dryden, Opasatika, Chapleau and Kirkland Lake.

Tyrvainen adds that Superior Thermowood wants to work with existing sawmills by purchasing raw material from them, which the company will use to produce thermowood. Superior Thermowood can also license primary and secondary wood producers so that they can use this method to manufacture thermowood products, as well as supply them with the Eco-dryers and accompanying control systems. These highly specialized units will be built and assembled at the company’s headquarters at Kakabeka Falls, west of Thunder Bay.

Arvo Tyrvainen (right) and Mike Joseph (left) of Superior Thermowood (pictured this past summer), with a thermowood kiln under construction.

Using extreme heat to treat wood is not a new concept. However, Finland has invested significant amounts of research and development money into advancing the thermowood process as an environmentally- friendly alternative to the use of chemical preservatives, such as chromated copper arsenate (CCA), amine copper quat, ammonia cal copper zinc arsenate and copper azoles.

Finland’s thermowood association presently has 12 members, each with their own recipes of using high temperature heat, moisture, and time in a variety of dryer styles to create what is considered a thermowood product.

The thermowood process is essentially an aging or petrifying process that enhances wood’s natural properties. Using extreme heat—reaching as high as 230 degrees Celsius—in combination with moisture in a highly controlled kiln environment for up to 48 hours, the wood’s molecular structure is realigned and moisture content is reduced to less than eight per cent. This allows the wood to better withstand fluctuations in humidity and temperature, improves its durability against attacks of fungus and rot. It also improves its stability, thereby reducing distortion, swelling, and shrinkage.

Naturally occurring protective agents found within the wood are activated and together with the reformation and realignment of the cells, a natural moisture barrier is created. In addition, the sugar content is broken down and is rendered unusable to rot fungi.

For the moment, thermowood is intended strictly for aboveground, non-structural use. Superior Thermowood says it will meet the standards established for thermowood in Finland, producing Thermo S- and Thermo D-rated products.

Advances in computer automation have made it possible to both monitor and make minute adjustments to the drying process to ensure that the process works consistently and according to specifications. Superior Thermowood has perfected and taken full advantage of this technology to control the process and manage the oxygen within the unit.

In addition to changing the molecular structure of the wood, the process also changes the colour of the wood and can be controlled to deliver various shades of grey, light tan, dark brown, and everything in between. The colour change permeates the wood material entirely.

Since the wood enters the Eco-dryer in rough green condition, any planing, ripping and sawing is done after the drying process.

Not only is this process touted as an environmentally-friendly alternative to using chemicals as a wood treatment, Superior Thermowood says that the heat treatment process itself is environmentally friendly. No off-gasses are created, as the design of the kiln circulates these gases back to the burner where they are incinerated. “You could be standing 15 feet away and there is virtually no odour telling you that a thermowood drying process is underway,” says Tyrvainen. “There is nothing more than trace elements going into the atmosphere in terms of smoke or pollutants.”

The concept is to construct a series of Eco-dryers on one site and to recycle the heat and water from one dryer to the next, so that it operates as a highly efficient closed loop system.

Superior Thermowood definitely believes there will be significant market demand for its product.

Arvo Tyrvainen and Mike Joseph with thermowood equipment. One of the main attractions of thermowood is that the colour of the wood can be changed by changing the drying recipe (inset photo).

According to a publication put out by the Canadian wood preservation industry, approximately 827 million board feet of Canadian lumber was treated with some form of chemical in 2004, of which approximately 50 per cent, or 414 million board feet, was treated with CCA. Most of that material was used in residential applications such as decking and fencing.

Total revenue from treated wood sales was estimated at $1.4 billion.

With the company in start-up mode, Superior Thermowood intends to direct its marketing efforts to wholesalers. Among the product applications where thermowood can be used are decking, cladding, windows, doors, fencing, flooring, trim and furniture.

In terms of target markets, the company believes it has tremendous potential in areas where chemical wood preservative usage is being discouraged or banned, yet manufacturers still need to offer durability performance guarantees to customers in environments where use of treated wood is essential.

Thermowood is already marketed in Canada in a limited way, but is an imported product.

Superior Thermowood is the first company to build a production facility in North America, and owns the licensing rights on this continent to a process developed by a Finnish company called Suomen Ecopuu Oy and Thermo Timber.

Tyrvainen says that over the past four years, the company has been conducting research and development in conjunction with Lakehead University (see sidebar story). It believes it has a more advanced dryer design versus what currently exists among Finnish thermowood producers. “Our Eco-dryer units and our process have been substantially refined and advanced compared to what is currently available,” he says. “We’ve probably gone five steps forward of what we’ve seen out there.”

The company is working with Mathew Leitch at Lakehead University, who has taken a personal interest in the technology. He is providing the critical third-party review that Superior Thermowood believes is essential to gain market acceptance. Leitch is assessing the impact the thermowood process has on wood with research funds provided by the Ontario Living Legacy Trust program and the federal government.

Some of his findings are contained in a report called, “The Market Preview Plus Report For: The Heat Treat Process.”

Tyrvainen says before the company could provide assurances that its process was legitimate, it needed the science to back its claims in terms of the product’s durability, stability, and machineability. It also needed to know how common Canadian softwoods and hardwoods would react to the thermowood process.

That was part of the research program, where a prototypical thermowood kiln based on the Finnish template was manufactured to study the reaction of common Canadian species to the thermowood drying process. Those results are now available and the thermowood process has been validated, which prompted Superior Thermowood to proceed to the commercial production stage. At present, its testing has focused on rough sawn lumber that is one and two inches thick.

Tyrvainen says performance guarantees will be offered with the product, depending on how it is used and installed. He adds that fire ratings based on research from Finland basically meet the standards of traditionally dried lumber.

The company is also working with Lakehead University to secure funding for a smaller test kiln. The university would use this kiln to continue to study the reaction and performance of many different species to the thermowood process, including widely available and fast growing under-utilized species such as black ash, tamarack and poplar.

Using the Finnish design as a template, Superior Thermowood estimates that a single Eco-dryer will cost about $1.15 million, with each dryer capable of processing 22,000 board feet per cycle.

The Eco-dryer consists of an oxygenfree controlled and managed environment with heat provided by a specialized fuel oil burner provided by Maxon Corporation of Muncie, Indiana. The burner is fed compressed air to facilitate the burning of fuel. It is also capable of burning natural gas or propane.

Superior Thermowood estimates that the energy and labour in the thermowood process will add about $106 to the cost of a thousand board feet of softwood and $134 to a thousand board feet of hardwood.

A number of investors located in northeastern Ontario, British Columbia and Minnesota have expressed a keen interest in establishing a thermowood manufacturing facility in their respective communities. Wholesalers have also expressed serious interest in purchasing the product, including a wholesaler that supplies a major big box store chain that is interested in becoming the exclusive distributor of the company’s product. However, company management understands that commercialization of their thermowood product has reached a critical point that requires very careful forward movement.

“Obviously, you have to walk before you run,” says Tyrvainen. “We want to have this perfected here in our facility before we take it to other places. Then we can basically cookie cutter it, taking what we have and replicating it. We have investors just waiting for a phone call from us telling them we’re prepared to move forward.”


Testing shows thermowood process works

“Our results show that the thermowood process very clearly does work.” That was the conclusion of Mathew Leitch, assistant professor in Lakehead University’s Forestry and Forest Environment faculty, after extensive testing of the mechanical properties of various species treated using Superior Thermowood’s drying process in a prototype kiln.

“They’ve also made improvements on Finnish systems,” he adds. Leitch says that the Finns ran into a problem where thermowood actually had reduced mechanical properties versus standard untreated wood, such as becoming more brittle.

“The Superior Thermowood people put a lot more effort into controlling the process and, as a result, their product came out equal to or better than standard untreated wood in terms of their properties,” says Leitch.

In addition to its echanical properties, he sees the product’s selling point as being a cheaper alternative to popular, visually attractive wood species used in interior applications. For example, it is possible to take a pale coloured wood like poplar and deepen its colour to as deep as black walnut.

“The time that you run the kilns at the top temperature is how you control the colouration of the wood,” he says. “So, if you want a really deep colour wood, you run it a bit longer at the highest temperature. We’ve got samples of poplar that you would swear are walnut or western red cedar.” He sees tremendous potential in using the process to add more value to under-utilized species such as poplar, certain species of cedar, tamarack, black ash and birch. “It is possible to take something that is considered a less commercial species and add a high value to it, rather than it being wasted or chipped for pulp,” he says.

The drying technology also has the potential to have a major impact on the manufacture of wood flooring. The thermowood drying process reduces the wood’s moisture content to between six and eight per cent. Flooring manufacturers now demand wood with moisture content of no higher than eight per cent. This process dries the wood down to that magic moisture content much more quickly.

“You can take green wood and the drying is done in 32 hours using the thermowood process,,” says Leitch. “Using traditional kilns, it can take four to five weeks in a kiln running at 105 degrees Celsius. So there are energy savings to be had.”


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