The term "multi-wall" refers to multiple plies of kraft paper and other materials used to construct paper shipping sacks. Multi-wall sacks are flexible containers made of two or more plies (walls) of paper or other protective barriers. The most common types of these bags are shown below:

Sewn Open Mouth Gusseted Sack (SOM) - The bottom closure for this sack is made in the factory, and the top closure is applied after the bag is filled. The top is usually sewn by the users after filling with automatic or semi-automatic machines.

Pasted Valve Sack (PVSE) - This bag is completely fabricated in the factory with an opening or valve in one corner through which the sack is filled. The valve is made with an inner flap which functions as a self-closing check valve after filling. It is available with a plain valve or with an extended inner sleeve of paper or film. It is also offered with a "tuck-in sleeve" which can be tucked into the bag after filling for positive closure. Sleeves that are thermoplastics coated can be heat sealed for a sift-proof closure.

Pasted open mouth "stepped-in" sack (PBOM - Pinch) - A pasted bottom open mouth sack manufactured with stepped walls at the top. After the sack is filled, these walls are folded to form a multi-ply, sift resistant closure by reactivating a factory applied hot melt glue.

For estimating the size of a bag based on bulk density please click on ESTIMATE.

To calculate sack size by product density: Calculate