HALF-GROUT — In mosaics, half-grout refers to a layer of cement-based tile adhesive or a mixture of cement and sand. It is applied to the base with a depth of approximately 5mm, although this can vary depending on the thickness of the tesserae.

The purpose of half-grout is to provide a surface into which the tesserae can be pressed if they are not suitable for standard grouting. This technique allows for better adhesion and ensures a secure placement of the tesserae, resulting in a more stable and visually appealing mosaic design.