Say what?!

A glossary of terminology related to packaging supplies, bags, bulk totes, and stretch film.


A reinforcement applied to the corners of bulk totes (or FIBC bags) that help prevent bulging and allow them better retain their shape when filled.

Biaxially oriented polypropylene (BOPP)

This is a polypropylene film that has been stretched in both directions during the manufacturing process to create a film that is stable, has high tensile strength, is essentially waterproof and has extremely low toxicity. It is glossy, takes printing exeptionally well and is also easy to laminate onto other material, such as polywoven fabric. It can be made to be crystal clear, translucent, opaque or metalized.

Bleached paper

Paper that has been chemically treated to turn naturally brown fibers white or nearly white.

Cast film

An affordable, quality stretch wrap that is exceptionally clear, glossy, quiet and resistant to tearing.


A unit of measurement for fibers. The larger the number, the larger and heavier the strand of fiber. A strand of silk is roughly 1 denier.

Four-panel construction

A bulk tote with the four sides made from four separate panels sewn together.

Kraft paper

A smooth, brown, strong style of paper made using the kraft process of papermaking (the term “kraft” comes from the German “kräftig,” which means “strong,” “sturdy” or “stout” )

Pasted valve bag

A paper bag that has its bottom and top pre-sealed while the bag is still empty. But the bag also has a valve installed in one corner, which is used later to fill the bag.

Polypropylene (PP)

Light, durable thermoplastic with a high melting point that is often used to make packaging.

Polypropylene resin (PP resin)

The thermoplastic substance used to make many common products. Polypropylene resin can be virgin or recycled. Recycled resins can have less consistency than virgin resin and end products made from recycled resin may be more brittle and slightly less strong.

Polywoven fabric (also, PP woven fabric, PPW fabric, polypropylene woven fabric)

A textile made of polypropylene strands in a standard weave. It is extremely strong and resistant to tearing and punctures.

Pre-stretched film

Film that has been stretch before going on the roll. It ends up requiring less tension to apply and usually results in less film being used on any given wrap job.

U-panel construction

A method of making a bag using three pieces of fabric, one that forms two opposite sides and the bottom (the “U”), and two other panels to fill in the other two sides.