Infrared heat dries stain on wood panels faster

Infrared radiation dries wood panels treated with water-based paint stain faster than other drying methods. Medium-wave infrared radiation is an optimal match for water-based coatings.

In the production of furniture, panels of untreated wood are color-stained and then coated with a UV varnish. The stain must be completely dry before the UV coating can be applied. Water-based color stains can cause problems here because water dries relatively slowly. One solution is infrared emitters that are precisely matched to the drying of water-based coatings.

A Scottish company compared different technologies in their search for an efficient drying method. They initially considered gas convection ovens, but rejected them because they would have required a footprint of about 20 m and a dwell time of about 30 minutes for complete drying. Finally, the decision was made to use two medium-wave infrared modules from Heraeus Noblelight. They are only about two meters long and, with an output of 12 kW each, dried the plates completely, even at a line speed of 10 m/min. The infrared modules reach the required temperature in less than two minutes, so they can be switched off at lunchtime and during longer breaks, unlike gas ovens that have to be kept at temperature throughout the working day. This helps make paint drying extremely energy-efficient.

Since the introduction of the VOC regulation, many companies in the woodworking industry are switching away from solvent-based coatings and towards water-based coatings. However, the more environmentally friendly paints and varnishes require further thinking when it comes to varnish drying, because water evaporates more slowly than solvents. As a result, existing convection ovens are no longer sufficient for drying. If the drying distance remains the same, the throughput speed must be reduced.

Extending the hot-air drying section is not always possible, if only for reasons of space. In any case, this can lead to a production bottleneck that no coater can afford. One measure to counter this can be to switch to infrared heating technology. Heraeus Noblelight offers infrared emitters that are precisely matched to the drying of water-based coatings. Compactly designed infrared modules make it easy to upgrade existing dryers. (OM-09/23)