1. Uneven rubber mixing and irregular operators.
2. The parking of rubber films is not standardized and the environment is unsanitary. Management is not standardized.
3. The material has moisture (add some calcium oxide when mixing)
4. Insufficient vulcanization, unfamiliar looks like bubbles.
5. Insufficient vulcanization pressure.
6. There are many impurities in the vulcanizing agent, the impurities of small molecules become decomposed in advance, and the bubbles remain in the product
7. The exhaust design of the mold itself is unreasonable, and the air cannot be exhausted in time when the rubber is punched!
8. The product is too thick, the rubber material is too small, and the rubber heat transfer is slow. After the surface is vulcanized, the fluidity of the rubber decreases, resulting in a shortage of materials, so air bubbles may be generated.
9. The exhaust gas was not exhausted during the vulcanization process.
10. For formulation issues, the vulcanization system should be improved.

Solution: improve the vulcanization pressure and time
1. Extend vulcanization time or increase vulcanization speed.
2. Pass several times before vulcanization.
3. Exhaust more frequently during vulcanization.