Concept:
During glass melting, gases may remain trapped in the molten glass as bubbles. Removing these bubbles is an important stage.
Step 1: In glass melting, batch materials melt and form molten glass.
Step 2: During melting, gases such as \(CO_2\), \(SO_2\), and air bubbles may remain inside the glass melt.
Step 3: These bubbles reduce the quality and transparency of glass.
Step 4: The process of removing bubbles and making glass homogeneous is called refining or fining.
Therefore, making glass bubble free is called:
\[
\boxed{\text{Refining}}
\]