Why temper chocolate?

Tempering is the key to making small chocolates, bars, molded chocolate, and decorations. Merely melting a bar of chocolate is not enough for it to retain its qualities when used in another form, such as orangettes and mendiants. Only if the tempering is properly carried out will chocolate snap briskly, melt in the mouth pleasantly, and retain its gloss.

This fatty matter is complex and capricious. Insofar as a human attribute can be given to it, it can be described as “lazy!” Once it has melted, it cannot regain its stable crystalline form. This means that its component crystals are scattered. One result of this phenomenon is the “bloom”—the whiteish streaks—you sometimes see on slabs of chocolate.