Answer: to fill a crack on a wall.
The calico is a non-woven, nylon or fiberglass strip, used to fill large cracks in a wall. Once enlarged and cleaned, the crack must be generously filled with a filling plaster on which you apply the calico. It must follow the path of the crack and go far beyond it to be effective. If the crack is zigzagged, it is better to cut several pieces of calico and make them overlap. The filling coating must penetrate and overflow onto the calico which must then be invisible. With a coating knife used to smooth, you will get an almost flat surface, and the calico will be gone, drowned in the coating. It is only when everything is dry that you can sand. There are specific reinforced banners for the corners of the walls. You too, send us your DIY question.