Watering the gunite shell is crucial because it keeps the concrete from drying out too quickly. Gunite hardens through a chemical reaction called hydration, which needs moisture to reach full strength. If the shell dries too soon, it can weaken, crack, or become more porous. By spraying it down a few times a day for the first week, you help it cure evenly, prevent shrinkage cracks, and make the shell denser and more watertight — which sets a solid foundation for the plaster finish later. | Austi