The best storage temperature for chocolate is a constant 60–65°F/15–18°C, without fluctuations that would encourage the melting and recrystallization of the cocoa butter fats. Sometimes stored chocolate will develop a white, powdery-looking coating on its surface. This “fat bloom” is cocoa butter that has melted out of unstable crystals, migrated to the surface, and formed new crystals there. Fat bloom is normally prevented by proper tempering of the chocolate in the first place. Its development can be slowed down by the addition to the melted chocolate of some clarified butter, which makes the mix of fats more random and so retards the formation of crystals.