Dear Mr.ADOLFO QUISPE B,

Did you preheat the splice area prior to joint?

Regards, ■

Air bubbles (sometimes called blisters as well) are typically caused from moisture remaining in the splice area prior to cooking. During the cooking process that moisture turns to steam and causes the bubble. Over time this bubble will spread larger throughout the splice area as it is stretched over pulleys and impacting from product and will eventually find its way to an edge or break causing carcass or cable exposure. ■

I moved your thread to a more appropriate forum where you will get more responces form the great members on this site. ■