What Is a Skirt on a Flat Bag?

Sometimes a flat foil pouch has a small amount of material extending beyond its bottom seal. This is called a skirt, and it is more commonly seen in large format bags. Skirts are generally no more than 2-5mm and their presence does not affect the bag’s performance.

Why is there a skirt at all?

The manufacture of flat pouches begins with rolls of film (or webs) that are sealed and cut into individual bags. Most large flat bags are produced with three sealed sides and one open side. After the bottom seal is made, a cut is made under that seal to separate individual pouches. There is a risk that this cut might be too close to the bottom seal if not precisely aligned. Cutting into the bottom seal would not only compromise that seal’s integrity - it would also mean that the top of the next bag would be sealed rather than open.

In order to avert this disastrous outcome, bags produced in this way are usually cut slightly under the bottom seal, which thereby creates a “skirt”. This extra material is harmless, and usually goes unnoticed.

Can a skirt be avoided?

Of course, bags are frequently produced with no skirt at the bottom, particularly when a pouch has to conform to strict parameters. This requires employing a production technique that will create a precise edge at the bottom of the seal in question. In other words, if you would like for a pouch produced for you to have no skirt, this must be specified!

To learn more, contact IMPAK to discuss custom pouch production. Our experts will be happy to explain what is required for making a pouch with or without a skirt.