Dental The porosity formed due to simultaneous nucleation of solid grains and gas bubbles at the first moment that metal freezes at the mold walls is called: A Pinhole porosity B Gas inclusion porosity C Micro porosity D Subsurface porosity. 💡 Explanation The porosity formed due to simultaneous nucleation of solid grains and gas bubbles at the first moment that metal freezes at the mold walls is called: ✓ Correct Answer: D. Subsurface porosity.