Thanks for those replies,
I know the process works well,
I am just looking for a explanation, perhaps more scientific as to what forces the air out, It must be the pressure that causes the air to move in a horizontal direction an go out between the layers of the rubber and then past the rubber and mold frame. But I would think that an air bubble could still get trapped in place under pressure, of course this bubble would shrink in size under pressure but I dont think a vulcanizer is designed ti do that.
If any one knows whats the physics going here, I would love to know.