In this configuration, a knife is set at a specific gap over a roller. The 1) size of the gap, 2) viscosity of the paste, 3) angle and profile of the knife, and 4) the speed of the line, all contribute to the amount of chemical add-on.
In this configuration, a knife is positioned over “air”. The fabric is supported by either rollers on either side of the knife, or by a table. The 1) tension of the fabric, 2) viscosity of the paste, 3) angle and profile of the knife, and 4) the speed of the line, all contribute to the amount of chemical add-on.
A roller, rotating in the opposite direction to the fabric, is used to apply chemical to the surface of a fabric.
This process is similar to Knife Over Roller coating, but instead of coating the fabric with a paste, a foam is used. This is generally used for open or stretchable fabrics. The finished product usually exhibits a softer handle fabric than a paste coat, as the chemical tends to sit on top of the fabric and there is very little penetration. The finished product is usually air permeable and therefore is not a good technique for waterproofing of fabrics, but is suitable for filtration products.