process of moistening leather in preparation for some other process
Casing
Moistening the surface and part of the thickness of veg-tan leather in preparation for tooling is often called “casing”.
Tempering
Moistening veg-tan leather through its entire thickness, then allowing a substantial amount of the moisture to evaporate, is often called “tempering”. Insole leather is often tempered before forming to the bottom of a last, such as by submerging entirely in water until fully saturated, then left wrapped in paper or fabric for several hours.