Why did my IDF Filter Bag (or Flow-Thru bag) develop small holes during the sample digestion step after the defat process?

In the past, we recommended customers to de-fat in XT4 bags. When the defatting process was completed, the XT4 bags were cut up and placed in the IDF bag. If the XT4 bag is cut into very small pieces, the sharp edges of the cut pieces can penetrate the clear polypropylene IDF bag, potentially causing leaks. We no longer recommend defatting in XT4 bags. We recommend that you refer to official methods that describe the defatting process, such as AOAC 985.29.