In production coating, the web must first pass through a wetting station and then to the
metering rod in order to be coated with a uniform liquid film[3]. The coating liquid can be
applied to the web by different methods. For example, the web can be immersed directly
into a tank as shown in Figure 2; or an applicator can be rotated in the reservoir to transfer
the liquid to the web at the top of its rotation as shown in Figure 3. The metering rod
usually rotates in the same or opposite direction to the web movement to even out the wear
on the wire and to loosen any dirt particles caught between the web and the rod that could
cause streaks. Whichever direction the rod rotates to produce the best coating, the wire
should be wound in such a way that rotating the rod tightens the wire [4]. The web should
pass above the rod, to allow the excess liquid to fall back into the tank. However, the web
does not need to be perfectly horizontal, as long as the surplus coating can return to the tank
through gravity