Before pouring the cast iron into the mold, a silicon-based subconium nucleator is added to the melt to control the solidification process. This nucleator creates the desired microscopic structure and mechanical properties in the cast iron.

The nucleator works by the following two mechanisms:
1- Adding the nucleator creates nucleation sites during solidification of the melt and creates a uniform distribution of graphite particles and the desired structure inside the part.

2- By reducing the undercooling range in the melt, it prevents the formation of chill and brings the solidification onset temperature closer to the eutectic stable temperature, which results in the formation of graphite instead of cementite.

The nucleator is mostly added into the ladle with a grain size of 2-6 or into the mold during the melt (in stream) with a grain size of 0.6-0.2.

However, in a completely specialized way, to improve and increase its effectiveness, it can be applied in a block and directly (in mold) inside the mold.