As we can see, there will be no bubbles in the appearance of a good quality paper bag. So in case that happens, we should be careful when in the process of lamination.
There are some tips as following:
First, increase the amount of glue instead of powder. Then the glue can mix with powder as much as possible.
Second, the paper should be cleaned up before lamination in case of some chemical reaction.
Third, the temperature should be high when dry the paper .
Fourth, check if the glue is still good or not,some factories don't care about the quality of glue, they think it is not a problem. Actually they are wrong. Good glue is the important key for making paper bags. We can not igore it.
Well, in order to produce good quality paper bags, we should be carefel with every process.