Process and apparatus for coating a porous substrate with a coating liquid

A process for applying a uniform coating of a coating liquid to a surface of a porous substrate, comprising:

• (a) providing an apparatus having a platform for placement of the porous substrate disposed in a coating vessel, said apparatus also having an engagement head including a sensor array and a plurality of extendable and retractable pins for engaging, retaining, and releasing the substrate evenly into the coating vessel, wherein the plurality of pins are arranged in a plurality of parallel pin rows at a predetermined pin angle, wherein pins of immediately neighboring pin rows are arranged such that pin angles for the pins in a pin row are inversely symmetrical to pin angles for the pins in a neighboring pin row;
• (b) placing the coating vessel containing the substrate on the platform of the apparatus;
• (c) extending the pins of the engagement head to engage a surface of the substrate;
• (d) lifting the engaged substrate out of the coating vessel;
• (e) verifying that the substrate is evenly engaged using the sensor array;
• (f) pouring the coating liquid into the empty coating vessel;
• (g) after the coating liquid has been poured into the coating vessel, lowering the evenly engaged substrate to a release position, and
• (h) retracting the pins of the engagement head to release the substrate evenly into the coating vessel thereby enabling uniform coating of a surface of the substrate.