The exterior shell covers and protects an inverted cup shell where you put the butter in. The inner cup is placed upside down after having added water to the exterior shell, up to the level marked outside. Add a pinch of salt to the water. When you place the cup down, it creates a vacuum-seal kind of effect, and this keeps the butter fresh and spreadable. I change the water every 4 to 7 days. I keep the crock on my kitchen bench, away from the sun and from any heat source; no mould so far! The container outer shell is quite large, but the amount of butter you can put inside the storage cup is about 150 grams. It washes easily by hand or in the dishwasher. I love this crock!
