Difference Between Gas Voids & Vacuum Voids

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Difference Between Gas Voids & Vacuum Voids

Last updated on Jul 22, 2026

Key Summary

Voids are mainly divided into two categories: one formed by entrapment of large volumes of gas, and the other caused by resin shrinkage in thick-wall sections. The former is defined as Gas Voids, while the latter is Vacuum Voids (Shrinkage Voids).

X-Ray Images

Normal (No Voids)

Abnormal (With Voids)

Gas Voids Mechanism

Gas → Accumulation → Void formation

Vacuum Voids Mechanism

Solidification → Outward Shrinkage → Void formation

🔍 Root Cause

Gas Voids: Entrapped gas congregates within molten resin to form cavities.

Vacuum Voids: Resin in thick sections shrinks outward during solidification and creates cavities.

👁 Visual Characteristics

Gas Voids: Relatively scattered voids with irregular sizes.

Vacuum Voids: Mostly located at the center of thick-wall areas, with relatively regular shape.

📑 Judgment Method

Gas Voids: Identified via X-ray inspection, cross-sectioning or dissection analysis.

Vacuum Voids: Identified via X-ray inspection, cross-sectioning or dissection analysis.

Figure 2: Distinction between Gas Voids and Vacuum Voids

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Difference Between Gas Voids & Vacuum Voids