There is a crack in rubber products
It is possible that the sulfur is too fast, the outside is ripe and the inside is slow cooked because of the uneven expansion
The additive time temperature and pressure of semi-finished shapes semi-finished semi-finished products placed as far as possible when placed speed gap semi-finished size can be more appropriate to put five percent to ten percent semi finished mixing can put some help curing
I personally think and vacuum should be given no relationship, if it is the bubble, and vacuum will have relationship
