In pottery, leather-hard is the condition of a clay or clay body when it has been partially dried to a consistency similar to leather of the same thickness as the clay. At this stage, the clay object has approximately 15% moisture content. The clay is still visibly damp (normally a darkish grey, if it began whiteish) but has dried enough to be able to be handled without deformation. The body is able to be gouged or incised without breaking.
The leather-hard stage is the easiest place to add on extension material that cannot be dried with the rest of the pot without causing some issues to occur. For instance, in some cases when handles are added before the base and sides have been dried, the handle can dry before the sides do and cause cracking, as the weight of the dried portion is no longer at the same equivalence with the wet side. The same goes for other additions to the pot that will not dry at the same rate as the rest of the pot. These include bases that are not the same shape as the rest of the vessel, hand-built additions, or decorations on the sides.