Initiation of Crystallization - Nucleation Phase

Conversely, seed crystals can be introduced shortly after the system has become supersaturated, but well before the border of the metastable zone has been reached. This seeding avoids effectively spontaneous nucleation. 

This spontaneous nucleation has several drawbacks that are all about not actively controlling the crystallization process  

Although the control on the crystallization process by spontaneous nudeation is limited, this nudeation process is often used throughout the industry. 

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