Mongrel Investments has trained and experienced engineers and technicians that are certified for work in all Areas of Engineering.

Areas of service include;
• Installations of Wood Treatment Technology plants
• Repairs and maintenance
• Inspection, testing, reporting and customer training

Some of the plants included in Mongrel’s portfolio include:


The WTT creosote impregnation plant

WTT creosote plant is designed for the protection of building elements with particular heavy demands, and where special requirements to durability of wood in open area in earth (or water) contact are to be met.

This modern creosote oil process taking place in the plant is tailored for the new types of creosote, which are to be processed at the temperature of 130°C.

Due to the special construction with placing of the autoclave in the storage tank, the filling and emptying timings are extremely short and the loss of heat is very small. This guarantees an optimal penetration and impregnation. An optimal heat transfer is also ensured via a heat exchanger that constantly keeps the impregnating material warm.

The computer-controlled plant is safe for operation and eco-friendly, using a closed cooling system and integrated heating system

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ThermoTreat 2.0 – the most competitive solution on the market 

This unique thermo treatment plant is designed for heat treatment of 2 to 3 batches per day, depending on thickness and wood species. The plant is therefore equipped with a high performance energy and heat transfer system.

The heat is produced by a gas- or oil-fired boiler that heats thermal oil. The oil is used as heat transfer media in both the heating and cooling phase. In the cooling phase the heat is ejected in a dry cooler.

The product is pressurized in a controlled, oxygen free atmosphere during the heating and cooling phases, and with only a small amount of water steam.

The plant is controlled by the unique WTT ExoT control system which enables an unchallenged degree of control of the modification process.

The plant is the most advanced and most competitive solution on the market today.

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WTT vacuum-drying plant: quick drying and natural wood colors

WTT invented modern vacuum drying in the late 1970’s and has supplied more than 250 units over the years.

The vacuum-drying (VD) has 3 unique qualities which differentiate it from traditional kiln drying.

Firstly, it dryes 3 to 5 times faster than conventional kilns and at a lower energy consumption. In this way, VD offers high flexibility in meeting customer demands because of the short cycle time. VD is especially competitive for drying difficult hardwoods such as (pre-dried) oak and is primarily marketed in the hardwood industry where high and uniform quality is important, e.g. in furniture, flooring, kitchen, musical instruments etc. but also for construction. WTT recently dried WRC beams quickly and with good results.

Secondly, it does not darken the wood as traditional drying so that the e.g. beech wood remains completely white after drying; as demand for light rather than dark wood increases, demand for VD will increase.

Thirdly, VD is a closed system; a sawmill using traditional drying typically emit between 1.000 and 5.000 metric tons of VOC annually; in the VD, most of the turpentine is captured in the condensate. As environmental regulation increases in the future, VD will become more competitive.

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Ammonia treatment for beautiful dark wood

Ammonia (NH3) reacts with the natural tannins of the wood to create beautiful brown and even black colors, which give the wood a fine and authentic look. The colouring of the wood has the side benefit that it provides a better resistance against aging and light exposure. Additionally, the wood is plasticized, i.e., it becomes elastic, less brittle and thus easy to process.

WTT has developed a closed system for this, based on a standard vacuum dryer; thus, the NH3 unit can do both ammonia treatment and vacuum drying.

Ammonia is obviously hazardous and so the WTT closed system ensures that all HSE related hazards are controlled. Surplus ammonia from the process is neutralized with sulphuric acid to create a safe condensate which can be used as a fertilizer.

Ammonia treatment is used mainly in the hardwood industry (although it also works on softwoods – depending on their natural level of tannins) for flooring, furniture etc.

There has been a steady increase in this market over the years and WTT has supplied units to Germany, France and lately India.

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Hot Oil Treatment-Durable outdoor wood, treated with linseed oil

This process uses hot linseed oil as an after treatment of traditional biocide treated timber used for siding and other outdoor uses.

With added pigment, the process results in a ready to use product which is exceptionally dimensionally stable and will not require any after treatment (painting) for 5 – 25 years, depending on the actual climatic conditions.

After traditional pressure treatment with biocide, the water content is around 30%. The treated wood is taken directly to the hot-oil tank, where in an over a 8 hour process is dried down to a ready to use product with 8 – 12 % moisture. At the end of the process, the 1-2 mm penetration of linseed oil into the wood creates an envelope which effectively seals the surface of the wood. This reduces the fluctuation of the moisture content over the seasons significantly, thus giving the wood exceptional dimensional stability.

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Timber impregnation with contemporary technique

The goal of the modernized WTT compact high-pressure impregnation plant is to manufacture a complete turn-key plant in our workshop and thus a plant that is operational on the client’s site in a very short time.

More than 500 WTT impregnation plants have been delivered worldwide and work on a daily basis to treat wood, providing a first class protection against wood enemies, including rot and fungus attack.

The autoclaves have a recognized quality as per EN 13445 pressure devices-directive and EG guidelines for machines. The technical operation is performed as per the German WHG Water Resources Act. All plants are delivered with CE certificate.

The compact impregnation plant T10 can be supplied with one or more storage tanks placed below the autoclave.

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