This process relies on a coating being applied to the substrate which then passes through a 'gap' between a 'knife' and a support roller. As the coating and substrate pass through, the excess is scraped off. This process can be used for high viscosity coatings and very high coat weights, such as plastisols and rubber coatings. There are innumerable variants of the relatively simple process which is rugged, hard-working and somewhat inaccurate.
- In this configuration, a suitably designed doctor blade is properly positioned on top of a high-precision roller. The gap between the bottom of the blade and the thickness of the fabric that passes over the roller controls primarily the coating weight.
- The roll may be rubber covered or chromium-plated steel roll. The hardness of the rubber covered roll may vary from 60 to 90 shore, depending upon the type of fabric.
- Resin add-on influenced by fabric speed, surface geometry and construction. Smooth surface of closely woven fabric NEEDS low-add-on and vice versa. First layer which fills in the holes in the fabric construction is important which determines polymer –fabric adhesion DECIDES coated fabric handle.
