Latest process for thermowood

- very durable and cost-effective with low temperatures -

WTT has modified its thermowood process: the thermowood process developed few years ago is now employed successfully with new heat transfer.

Initially, the heat transfer was released with the aid of steam, which was very effective but it lead to problems with sensitive hard wood. The newly developed heat transfer is carried out through a stainless steel pressure boiler with double jacket. The process is quick, especially gentle and effective in heat transfer. Parts subject to wear and tear, for example ventilators, are not used in the boiler, only the pressure-resistant stainless steel container and the stainless steel trolleys are used for transporting the material.
A specialty of this process is that the wood is not entirely dried during the process but a residual humidity of about 6% HF remains preserved. The high rate of rejection in the traditional process that fully dries the wood, is thus minimized. This is good mainly for the sensitive woods and reduces the costs.

WTT has confirmed another advantage scientifically. The assumption that a pressurized thermal process reaches its full performance in the temperature range of 160-180°C , has been checked in the meantime and thus offers another significant advantage against traditional process that achieves this durability only at temperatures above 200°C . Any practitioner can imagine the effects, mainly with hard woods.

The wide colour spectrum is a positive side effect from this temperature range. Not only dark, almost black wood, but even light and medium-brown colour shades are possible with these low temperatures.

In the meantime, the WTT process has also verified the durability as per the normal standards EN 350-1, EN 113 and DIN-84. For some time, extensive static and biological tests have been carried out for six types of wood (oak, beech, ash, pine, spruce and fir) at the University Freiburg in Breisgau, Germany. In this connection comparisons to pressure-impregnated wood and other tests as per EN 807 were carried out.

The complete experiment report will be available shortly, but already at this time durability has been verified for (classification 1, very durable) beech, ash and spruce as per EN 350-1, EN 113.

After the operators have now some experience, statements can also be made on the processing costs. Normally, hard and soft woods are processed up to 60 mm within 24-40 hrs, whereby the complete costs from energy, depreciation costs and interests lie at the cost level of “normal” high-pressure impregnation. The WTT thermo treatment plants are ready for use within 48 hours, including heat generator, automatic charging and fully automatic control. Plants with an annual capacity of 1500-5000 m³ can be delivered. The plants are placed in a hall and ready to operate after being connected to main power supply, water and drainage.