Functions and Differences of Flexible FIBC Coatings
Flexible FIBCs are woven from polypropylene tape. Due to this weave, very fine materials, such as fine sand and powder, can leak through gaps in the weave or seams. If you use an uncoated FIBC to store powders, tapping one side of the bag will result in a cloud of dust leaking out. While this may not be a concern in some situations, it is unacceptable in others.
The construction of a coated FIBC is identical to that of an uncoated FIBC. However, before the bag is sewn together, an additional layer of polypropylene film is applied to the fabric to seal the gaps in the tape. The coating is common inside the bag to prevent powders from becoming lodged in the woven tape during unloading. If you are unfamiliar with FIBC, the coating may be difficult to detect. A simple method is to fold and squeeze the woven cloth to see if the flat wire is loose and moving. Remember to try it inside and outside the bag. If the flat wire does not loosen and move, then it can be determined that the bag is coated.