Textured paste. The Fine-grained sand effect mortar is a heavy-textured paste. It is often used to create a textured ground for painting or to create relief effects of fine-grained sand. The paste dries to a hard surface (within a few days) which the artist can cut and carve once it is thoroughly dry. It can be also used as a surface texture material and be over-painted with acrylic paints after 24 hours of application.