THERMAWOOD HEAT TREATMENT
Making Wood More Durable and Very Beautiful !
ThermaWood Heat Treatment is an environmentally friendly method that makes it possible to modify the properties and colour of the wood to suit market demand. During heat treatment, the wood (mostly light colour timber) is treated at high temperatures that can exceed 200°C, causing the sugar in the wood to decompose into compounds that cannot be utilised by decay fungi or insects. The timber achieves a beautiful and deep caramelized tone depending on the treatment temperature. The wood loses some strength and becomes more brittle at higher temperatures.
Heat treatment improves the dimensional stability and durability of wood. The temperature for heat treatment from 180 to 280 ºC can last up to 6 hours. The entire process takes from 2 days to 3 days, depending on the design of cooling system. Due to the thick insulation of the vessel, natural cooling can take up to a day.
It is important to highlight that the heat treatment process produces vapor that are slightly acidic and will have intense furan smell like that of BBQ corn. The process vapour will contain some wood acid, tar, and some volatiles found naturally in wood. The condensed liquid can be dark can slightly acidic and is good for gardening. However, one must be careful to ensure that the wood contains no impregnated wood chemicals. If timber contains resins, like Pine, there will be formation of tar in the chamber and also in the vapour released. Locations with strict emission requirements must engaged approved experts to scrub and neutralise the affluent.
Tritherm specializes in Thermal treatment of timber in a pressurized vessel.The pressure and steam in the vessel allow better control of the humidity in the vessel and gives better treatment colour and prevents the wood from cracking. The treatment pressure can be up to 4 to 6 bar. Therefore it must be made by an approved and certified pressure vessel maker.The vessel must be constructed out of stainless steel due to the acidic vapour inside.
Tritherm can supply treatment vessels for up to 8 m3 capacity, which can be loaded in a 40 ft container. Any larger capacity, the vessel can only be shipped on a flat rack or by conventional cargo. The shipping cost can be very high.
ISPM 15 Heat Treatment
International Standards for Phytosanitary Measures (ISPM) No. 15
The International Plant Protection Convention (IPPC) is an international treaty which deals with protection of plants and plant products by minimizing the spread of potential pests and diseases. Over 100 countries are members of the IPPC where they work collaboratively to set up the International Standards for Phytosanitary Measures (ISPM) No. 15 regulations which were implemented in March of 2004. Under ISPM 15, all non-manufactured wood packaging materials for export – including wood pallets, crating and loose wood dunnage – must be heat treated. Manufactured wood products such as plywood, oriented strand board (OSB) and particle board are exempted as the high temperature manufacturing process and the glue would have destroyed any pests.
Heat treatment involves heating the wood until its core temperature reaches 56°c for at least 30 minutes. This process is widely recognized as an effective means to destroy any pests that could be harmful to forests. Once a wood pallet is heat treated, it is considered suitable for export and re-export, as long as none of the original components are replaced. The pallet or wood packaging must be stamped with the internationally recognized IPPC markings and the license number registered in the country of origin. Tritherm provides ISPM 15 Heat Treatment Datal Logger with 8 and 12 wood core temperature points including the heating equipment and the prefabricated chamber.
Wood Preservation by Impregnation of Chemicals
Wood preservation is the pressure or thermal impregnation of chemicals into wood to provide effective long-term resistance to attack by fungi, bacteria, insects, and marine borers. By extending the service life of timber products, wood preservation reduces the need for harvest of already stressed forestry resources, reduces operating costs in industries such as utilities and railroads, and ensures safe working conditions where timbers are used as support structures.
Our chemical impregnation pressure vessel and equipment employs the Full-cell Process (Bethell Process) but with an additional vacuuming step to drain excess chemical from the wood so that no excess chemical drips onto the factory floor and also to reduce the drying time.
The 6 Process steps :
Step 1.) Loading in of Timber
Step 2.) Initial vacuum (635 mm Hg) for 15-60 minutes.
Step 3.) Filling the vessel with preservative solution.
Step 4.) Pressure (10-14 kg/cm2) for 1-6 hours.
Step 5.) Draining preservative after releasing the pressure. Apply Vacuum to drain excess preservatives in the wood.
Step 6.) Final draining of remaining preservatives and treatment is completed.