What is TMT
TMT, or Thermally modified timber, is wood that goes through a 3-stage kiln process using high temperature and taking from 24-72 hours to complete a full cycle. During the high temperature phase, the wood is protected from combustion by using steam. In that time, the moisture of the wood is almost completely removed and added back to a precise amount. The natural acids and sugars are modified from the extreme heat which changes the physical structure of the wood. The wood’s ability to absorb moisture is declined making it less prone to rot and decay. The equilibrium moisture content (EMC) of the wood decreases. This means the swelling and shrinking of the wood material due to moisture variations can be reduced by up to 60% as compared to unmodified wood. The most apparent change is that the wood darkens throughout, giving domestic wood the look of desirable imported wood.
The temperature in the kiln is raised rapidly to around 100˚C (212˚F), affecting thenatural composition of the wood. Steam is introduced to prevent the wood from checking in the high heat. The moisture content of the wood is reduced from 15-20% down to nearly zero.
One peak temperature is resulting in a light cook, 190˚C (374˚F), and the other is the dark cook at212˚C (415˚F). The higher and longer the heat, the darker the wood becomes throughout. Steam is used to prevent the wood from burning in the high temperatures.
Cooling & Re-Conditioning
The temperature is reduced by spraying water onto the wood and cooling. Conditioning and re-moistening take place to bring the wood moisture content around 4-6%