Trend-setting coating processes for wide and fast board machines

The traditional contour coating unit is the air knife. Well-known disadvantages of the air knife are the high investment and operating costs and also limitations concerning production speed and solids content Because of these disadvantages the papermakers' demand for new board coating technologies is steadily increasing. This article describes modern alternatives to the air knife concept The film application methods as well as the free-jet application principle by means of JetFlow Fare dealt with. On the basis of trial results it will be shown how the free jet application principle, for example, can be used advantageouly far the pre-coat as well as for the middle and top coat This permits avoidance of She disadvantages of the air knife without loss of quality and with higher flexibility of operation and offers at the same time new perspectives for fast and wide board machines.