Lock back — special feature found in dust-pressed tiles that facilitates their secure attachment to mortar or cement. It involves the presence of under-cut indentations on the back of the tile. These indentations create a locking mechanism when the tile is pressed into the mortar or cement during installation.

The lock back feature enhances the bond between the tile and the substrate, preventing the tile from shifting or dislodging over time. The under-cut indentations provide additional surface area for the mortar or cement to adhere to, increasing the overall stability and durability of the tile installation.