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Multi-Wall Kraft Paper Bags and Sacks in Caloocan City Metro Manila - Sky Industrial Bags, Inc.

Types of Sacks (Paper Bags)

The first basic division of paper sack types is into open mouth and valved designs. Each of these may be sub-divided into pasted or sewn closure types and into further subdivisions by the sack body being either gusseted or flat. Further minor variations can also arise from the inclusion of certain other design features.

Open Mouth Sacks

There are four basic open mouth sack designs depending on the type of closure.

Open Mouth, Sewn, Flat Sack

The name ‘pillow sack’ is sometimes used to describe this design, which has an inherent disadvantage in that, when filled, corners tend to jut out. These can give rise to difficulties after palletizing by snagging against objects to cause tearing and leakage.

Open Mouth, Sewn, Gusseted Sack

By having gussets inserted at the sides of the sack, the user is ensured of a rectangular block shape after filling.

Open Mouth, Pasted, Flat Sack

The pasted bottom closure will automatically give filled sacks a rectangular end, and a sewn closure at the top will allow them to be either butted or overlapped when stacked into pallets.

Open Mouth, Pasted, Double Folded, Flat Sack

A pasted bottom closure may be achieved on a flush cut multiwall paper tube by simply folding the bottom edge over twice and gluing. To ensure a strong closure, and to resist any tendency for the bottom to unfold, the outer ply is slit on the edges to form a flap which is adhered to the body of the sack above the folding. These sacks are also known as ‘Double Fold over’ and ‘Rollover Bottom’ sacks.

Valved Sacks

A valved sack is closed at both ends during manufacture and includes an entry device for filling purposes in one corner.

Valved, Sewn, Flat Sack

The valve of this sack can only be inserted by a complex manual operation during manufacture and the filled sack shows the disadvantage of protruding corners. It has been super ceded almost totally by the valved, pasted, flat sack.

Valved, Sewn, Gusseted Sack

This design of sack also requires complex manual corner folding for the valve insertion stage of manufacture. Although the presence of the gussets overcomes the protruding corners problem, the demand for this type of sack is negligible and it has largely been replaced by valved, pasted, sack designs.

Valved, Pasted, Flush-cut, Flat Sack

The use of a flush-cut tube is the simplest way to achieve a folded and pasted closure. Sacks made in this way are usually given an additional paper capping strip on each end to strengthen the closure and resist sifting.

Valved, Pasted and Sewn, Flat Sack

This design of sack enables a pasted valve to be used for filling and allows the final customer easier access to contents through the sewing line.