Definition - What does Curtain mean?
A curtain is a long horizontal run in a coating film that occurs on vertical surfaces when a coating is applied too heavily. This is a defect in the coating process.
Curtains make the surface look uneven and increase the probability of the inner material being exposed to outside elements, thus facilitating the corrosion process.
Corrosionpedia explains Curtain
The curtain coating process has been developed to prevent certain specific coating defects.
A curtain coating is a process where a substrate or other object is channeled through a falling film of coating.
There are two conveyors used in this process and the curtain of fluid is located between a gap in these two conveyors. The coating falls down in between the two conveyors. A tank containing the coating is used to supply the mechanism from which a thin coating film falls between the two conveyors. The coating’s thickness is often measured by the conveyor system’s speed and the rate that the pre-metered coating is drawn from the storage tank.
A curtaining appearance or the appearance of a long horizontal run after the coating process is completed is considered to be a coating defect. To prevent such defects the curtain coating process has been developed.
The converting industry commonly uses the curtain coating technique to coat a substrate.