Vallejo: Wet Palette SetIt consists of an airtight container containing a moistened sponge covered with a special sheet of paper that allows moisture to pass through. The container is composed of a lid and a base with a rubber seal that ensures watertightness and keeps the internal humidity for a long time. The sponge and the water needed to keep it moist are placed in the base. The hydration sponge is one of the key components of a wet pallet. Its primary function is to