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About | Decking
| Framing | Fencing
| Siding | Technical Info
What is Thermally
Modified Wood?
Thermal modification is the process
of gradually heating any species of lumber to temperatures
of 410 - 450º F in a special chamber that has had the
oxygen completely removed from the system. Steam is introduced
during this process to help stabilize the wood at these
temperatures. These conditions are needed to prevent the
wood from combusting, which takes place at temperatures
over 300º F.
Why Use Thermally
Modified Wood?
- Durability: 25
- 30 year life span can be expected for exterior applications
- Moisture Repulsion:
The process seals the cellular structure of the wood making
it impervious to water and moisture
- Stabilizaton:
Swelling and shrinkage is reduced as well as cracking
and checking
- Color: Consistent
brown color all the way through to the very center of
the board
- Chemical Free:
Chemicals are not used in the thermal modification process
which makes this product an environmentally friendly alternative.
Milling:
Sawing: Sawing does
not differ much from sawing untreated wood. Because of the
stabilization from the heat treatment, distortion of the
wood is greatly reduced after sawing. Since the thermal
modification eliminates the resins in the wood, machines
require little cleaning after milling.
Planing: Machines
well using all normal methods. Sharp Cutters provide the
best results, as with all woods.
Milling: Blades
must be sharp, otherwise tearout may occur. Milling across
the grain may increase tear out. Tearout is most likely
to take place at the end of a board where there is a thick
piece of wood behind the blade. Careful planning should
be taken into consideration.
Sanding: Material
sands generally the same as untreated wood. Due to the absence
of resins in the wood that has been crystalized in the process,
the sand paper does not load up like it does with untreated
woods.
Surface treatment:
Use surface treatment that will protect against Ultra Violet
radiation in order to prevent color changes and surface
shakes. Take into account that thermally modified wood has
lower water absorption than normal wood and needs a longer
time to penetrate the wood. Oil-based substances work just
as well as they would with normal wood.
Gluing: Longer
Processing time is needed for the glue to be absorbed by
the thermally modified wood, especially when using water
based glues. Because the thermally modified wood has a low
moisture absorption, penetration and drying time of the
glue is increased.
Screwing: Heat treatment
reduces the splitting strength of the wood. The use of self-tapping
or predrilling hardware is recommended. Also, the use of
stainless steel screws with less threads and countersunk
heads is recommended for external use and in humid environments.
We recommend not using galvanized fasteners as they tend
to leave bleed marks on the woods surface over time.
Nailing: It is recommended
to use a compressed air gun with depth control since hammer
contact with the wood promotes splitting. To reduce the
risk of discoloration from metal nails, the use of stainless
steel nails is recommended. Small oval head nails help to
reduce the risk of splitting as well.
For more information on
thermally modified woods, please visit this website.
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