The fats in cocoa butter can crystallize in six different forms (polymorphous crystallization).[54][55] The primary purpose of tempering is to assure that only the best form is present. The six different crystal forms have different properties.
Crystal Melting temp. Notes
I 17 °C (63 °F) Soft, crumbly, melts too easily
II 21 °C (70 F) Soft, crumbly, melts too easily