The slightly out-of-focus-pottery known as Flow Blue has gone in and out of fashion for two hundred years. Europeans tried to copy the porcelain coming from China but lacked the formulas for both the clay and the glazes. Imagine the disappointment those first potters experienced when they saw that their crisp blue designs were hazy---a chemical reaction between the cobalt-based decorations and the chlorides in their salt-glazed pottery. Somehow, this misty look caught on, but only to a degree. The "seconds" were sent to America, where you can sometimes see the flowiest of Flow Blue, with flowers barely discernable within the fog of cobalt.