Sawing of Thermo-treated wood does not significantly differ from sawing of untreated wood. Due to the stabilization of the wood after heat treatment process the effect of further distortion after sawing is reduced. As there is no more resinous substance in Thermo-treated wood, the saw blades stay clean reducing maintenance.
Planing of Thermo-treated wood is done using standard surface planers. The surface quality is good. As there is no more resinous substance in Thermo-treated wood, the blades stay clean reducing maintenance.
In order to get a good surface quality blades must be sharp, otherwise tearing may occur. Greater tearing is appeared when the wood is milled across the grains. The bigger problems are at the start and end of the milling, when the blade comes out of wood. The best results can be achieved when there is enough solid wood material behind the blade.
General working is the same as with untreated wood. There is very often no need for sanding, because after planing or milling Thermo-treated wood has good surface quality. Sanding is easy and the sanding paper is not clogging up by resin.
5. Surface treatment
To prevent color changes and surface shakes it is recommended that surface treatment against ultra violet radiation is used. Oil-based substances work as with normal wood. When working with water-solvent substances it has to be taken into account, that Thermo-treated wood has lower water absorption than normal wood. Water-based work well, when they are slowly drying and there is enough time to penetrate into wood.
Use PENOFIN, PROTEGO or HEMP SHIELD OIL to finish thermo-treated wood for outdoor applications.
See details in our Installation Instruction.
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Thermo-treated wood absorbs slowly water and water based glues, such as PVAc. That is why longer pressing times than normal is needed. Some PVAc glues can cause problems is substantially prolonged drying times due to the requirement of the water to penetrate into wood, e.g. the hardening of the glue is based on the water absorption into wood. When working with PVAc glue the water content of the glue should be minimized. PU (polyurethane) glues work well with Thermo-treated wood. Although when using PU-glues, it has to be kept in mind, that the hardening reaction of PU needs water. The water can be absorbed either from the wood or surrounding air. If both wood and air are very dry, gluing may fail. Chemically hardening glues allow unchanged drying times and other gluing parameters compared to normal wood. To prevent cracking it is recommended also to reduce the stress force in gluing machines when joining the Thermo-treated wood parts together.
7. Mechanical joints
Screwing. Heat treatment reduces the splitting strength of wood. The use of self-tapping screws or pre-drilling of holes is required to avoid splitting the material. With Thermo-treated wood it is recommended to use the less threaded screws compared with normal wood. Stainless steels screws with countersunk heads are most suitable in external usage or other humid environments.
Nailing. Recommended tool compressed air gun with adjustable nailing depth on the gun. Using normal hammer increases risk of splitting due to hammer contact with the wood. To reduce the risk of discoloration from nail in exterior application stainless steel are best, however if using compressed air gun fixing, galvanized nails can be used as no metal on metal contact occurs to brake the galvanized seal. Galvanized nails are also working, if Thermo-treated wood will be treated with covering paint after nailing. It is recommended to use small oval head nails to reduce the risk of splitting.
QUESTIONS AND ANSWERS
Our thermo-treatment process uses only water and electricity to create the desired results, minimally impacting the environment. Considering this along with the fact that chemicals are never introduced, you realize that you have real wood that is 100% environmentally safe and people friendly.
Thermo-treated wood (TT Wood) is relatively new to the United States, however it dominates the European market...
About fifteen years ago, the first technology for thermo-treating wood was created in Finland. The process was designed solely to treat softwoods with the intentions of producing an environmentally safe alternative for chemically treated wood. Since then, the technology has been significantly improved upon, but only Westwood's technology has revolutionized the thermo-treatment process making it compatible with both soft and hardwoods.
Is it true thermo-treated wood doesn't shrink and doesn't swell?
Yes, the dimensional stability is dramatically improved by 5-15 times when compared to non-treated hardwoods. The rule of thumb is the darker the color, the greater the stability. However, thermo-treated wood is STILL WOOD and can't be considered as stable as materials like stone. Some dimensional movements have to be taken into consideration.
Can thermo-treated wood be used when constant ground contact is unavoidable?
Research has shown that when thermo-treated wood is kept in constant contact with the ground it does not decay. However, due to the chemical processes that occur in wood kept in constant contact with the ground, there is some lose of strength. For the time being it is not recommended to maintain constant ground contact when using thermo-treated wood.
Is the color of thermo-treated wood consistent throughout the wood?
Yes, the color is consistent to the very center of the board.
What is the difference between thermo-treating Soft and Hardwoods?
Precise control is needed when treating hardwoods because of the exothermal reactions occurring in hardwoods. Westwood's advanced technology utilizes a 3-D Heat Wave control which was specifically created to treat hardwoods.
Can thermo-treated wood be glued?
Thermo-treated wood is suitable for jobs involving glue or paint. If water-based glue or paints are used, a longer penetrating time is required (mostly for softwoods). This is due to the diminished absorption of water and must be taken into consideration. If an oil-based product is used, simply follow the manufactures directions.
Is the smell of thermo-treated wood harmful?
The results of tests show that the smell of thermo-treated wood, similar to the smell of charcoal, is not at all harmful but may be unusual to some people. There is seldom any smell when the products are pre-finished. For unfinished products, this aroma will fade away after 1 to 2 months from the time of treatment. The tests also show that emissions from thermo-treated wood are 3 times less than non-treated.
Does the product have to be finished for outdoor applications?
Thermo-treated wood is still a natural, organic material and will fade in color from UV exposure. The brown tint will fade to a silver/gray over a 1 to 2 year period if untreated with a UV protectant. Although the wood is resistant to checking, it is more likely that checking will occur if a UV protectant is not applied. Checking of the wood has no effect on the long term durability or its resistance to rot and decay. In order to maintain and improve the woods performance against checking, and accentuate the natural grain structure brought out by the process, we recommend the use of a semi-transparent UV protectant. For example, PENOFIN® CLEAR is a commercially available UV protectant that works well with thermo-treated products. The application of a finish on a light-treated material is strongly recommended! Please avoid OVER-EXPECATATIONS related with the weather exposure of unfinished thermo-treated wood.
How often is maintainence rquired for thermo-treated wood Products?
Thermo-Treated wood products have increased dimensional stability which allows it to maintain its size. This ensures the products will not shrink or swell following the application of a protectant. When the product maintains its size it prevents the finish from cracking, which means fewer coats, less often. However to ensure you are receiving the best results from your protectant please follow the directions on the products' label.
Does the product have any guarantee?
The life cycle of thermo-treated wood is determined by the degree of temperature reached during the process and can be recognized by the various colors. A dark chocolate color is class #1 in durability, meaning it has a life cycle of 25+ years. A lighter (honey) color has a Class #2 durability rating and has a life cycle of 15 - 25 years*. Based on these standards, Westwood offers its customers a transferable limited 25-years warranty on thermo-treated wood products. *The life cycles are based on exterior applications.
What is the difference between the “heat-treated wood” and “thermo-treated wood” terms?
In the U.S. the term, "heat treated wood" refers to wood that is heated to temperatures around 130 deg F. The only purpose being to kill bugs larvae within the wood. Thermo-treated wood is a process that increases the temperature of wood beyond 400 deg F which creates a change in the molecular structure, resulting in a new generation of wood material.