Adding an inner liner to the big bag is the only way to completely assure container impermeability. With an inner liner, the product is totally protected from external humidity, as well as avoids leaks through the seams or fabric –for fine powder users. The inner liner can be incorporated in various ways:

• Free inserted. If the FIBC has a discharge spout, the liner is tied with it in the bottom.
• Placed and pre-blown. Before packaging big bags as a handling operation is done in which the liner is blown up and then incorporated to the big bag so that the product filling will be easier.
• Glued. The liner is glued to the inside body with a PP-appropriate adhesive called “hot-melt”. This fixing type avoids liner movements during the filling and discharging of the product.
• Sewn to big bag’s body. The liner is stitched to the top or lateral seams by inner welded fold which are sewn in the same seams as the big bag.

The inner liner would be in different shapes, raw materials and thickness depending on the further use. Usually, this liner is made in Low Density Polyethylene (LDPE), but it can be manufactured in HDPE, PP, aluminum or special composites as well. For each kind of goods we’ll study the best raw material to be used (alimentary goods, dangerous goods…).