Tempering (also known as pre-crystallization) is probably the most frustrating aspect of chocolate making, until you understand how it works. The principles are really very simple, and once mastered it is a very straightforward procedure. It is a bit like learning to drive: the sort of thing that you have to do by yourself a few times until you have mastered the technique. There definitely is a technique. The good news is that you can re-temper chocolate over and over again, so long as it has been melted correctly and does not have a sugar or humidity bloom (see Storing chocolate).