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Infra-red drying of coatings on wood

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WOOD is treated with a wide range of different coatings that need to be dried quickly but with care, to ensure there is no damage to the wood.

This requirement can be achieved with Heraeus infra-red technology.

Infra-red heat dries much faster than conventional hot air methods, because infra-red acts specifically on the coating.

Radiation, which is precisely matched to the absorption characteristics of the of the coating, is rapidly converted into heat, so that water or other solvents are evaporated, while the coated material and the immediate surroundings remain cool.

When compared with conventional heating methods, such as convection ovens, the gelling of powder coating, for example, with Heraeus infra-red heating is significantly accelerated. Rapid melting improves the coating quality and speeds up throughput.

Powder coatings can be baked into MDF and HDF plates with Heraeus short wave or CIR infra-red emitters, according to the absorption characteristics of the coating.

In the manufacture of laminated boards, there is a requirement to dry the edges of the boards. The front edges are coated with a water-based coating, which must then be dried as quickly as possible.

This is best done using a short wave high power emitter, which allows production speeds to be increased up to 180m per minute.

This careful heating of the material avoids stress on the surface of the wood. With a shorter heating time, the wood is not heated enough for the wood fibres to change their alignment because of the heating effect.

Moreover, because of the rapid heating, very little water can penetrate from the coating into the wood surface to soak the fibres. The infra-red heating also allows an improved quality of coating, no matter what the season, as it is independent of the storage temperature of the wood.

Heraeus offers testing in its in-house Applications Centre or on-site, to determine which infra-red emitters will provide the fastest drying and curing while providing optimum care of the material to be coated.

In this way, Heraeus matches infra-red emitters precisely to the requirements of the particular process, in terms of optimum wavelength of radiation and the length and power rating of emitter.

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