First, the appearance of inner rubber: this is the characteristic of pure EPDM, which is relatively Matt finish, not bright in appearance and low in strength. Our solution is to change the proportion of our formula and add natural rubber, which will make the appearance smooth and bright, and the strength will be correspondingly improved with greater toughness.
Second, the problem of water leakage
we should increase the process of filtering rubber to prevent impurities in rubber leading to poor adhesion;
Then the inner rubber is extruded ,The inner wall will be even, not uneven;