Surface bubbles or defects: Surface bubbles or defects may occur during the vacuum casting process.

Possible causes include:

(1) Air bubbles: Air may not be completely eliminated during silicone mixing, stirring, or filling, resulting in bubbles in the silicone.

(2) Rough mold surface: Rough, scratched, or other uneven mold surfaces prevent complete contact between the silicone and molds during the filling process.

(3) Inappropriate mold release agent: The mold release agent used may not be compatible with the silicone material, increasing surface adhesion and causing bubbles or defects.

Here are some methods to address surface bubbles or defects in vacuum casting:

(1) Mixing and degassing: Thoroughly mix the silicone and use a vacuum degassing device to remove any trapped air during the mixing process. Ensure there are no noticeable bubbles in the silicone.

(2) Mold surface treatment: Ensure the mold surface is smooth, clean, and free of scratches. Grinding, polishing, or other surface treatment methods can be used to make the mold surface smoother.

(3) Proper use of mold release agents: Select mold release agents compatible with the silicone material and apply an appropriate amount according to the instructions. Ensure the release agent is evenly coated on the mold surface to reduce adhesion.