Contact Us On: 01773 820415 or Enquire Online

What are Skirt Side Weld Bags?

In packaging, design is often more important than material choices. Polythene bags might seem simple – and they can be – but when they need to do more than your average garden variety polybag, the material won’t change drastically; the design will.

Of the many iterations of polythene bags in the world, skirt side weld bags are a variation that came into existence out of necessity. And necessity, as they say, is the mother of invention.

This versatile solution offers enhanced strength due to a unique sealing technique, which gives it characteristics unlike simple seam welded bags. The applications of skirt side weld bags are wide-ranging, and they have become indispensable in many industries.

So – what are skirt side weld bags?


A side skirt weld bag photographed from inside, giving a bueish hue and an abstract appearance


A stronger kind of polybag

Skirt side weld bags offer all the strength of a bottom weld bag, with the versatility of a standard side weld bag. This enables self adhesive strips, one-sided tear perforations, and so on. Strength-wise, skirt side weld bags are on a par with bottom weld bags, but stronger than a traditional side weld bag.

Generally speaking, polythene films and bags are welded as they’re cut – especially for light duty applications where strength isn’t paramount.. For instance, layflat tubing is often heat sealed, which cuts the polythene and creates a welded seam behind it, sealing the film and the contents within. This is fine for general and light duty packaging – but it doesn’t create a reliable watertight seal and can easily be torn.

Skirt side weld bags stand out due to their distinct welding method, which creates an extremely reliable and strong seam that’s usually harder to tear or notch than the surrounding material.

A side weld extends beyond the bag’s edges, creating a more extensive surface area for sealing. Picture a crisp packet: the edge you open up is a side weld, where two long, wide and flat surfaces of the packaging are welded together. Of course, those are designed to be opened easily – otherwise you’d be getting into fights with crisp packets on the regular!

But the principle is the same. More surface area = a better seal.

The extended weld adds strength and creates a watertight seal. This means that if you’re packaging items for shipment that need total safeguarding from moisture, skirt side weld bags are probably the most reliable and cost-effective solution. The secure seals also make it possible to package liquids reliably – and are also useful for transporting live fish in large quantities of water. They are commonly used in koi trading and eventing, where water-filled bags also need to be pressurised with oxygen.

Read more: How To Transport Koi With Polythene Bags

Side welds in automated packaging systems

Skirt side weld bags are particularly valuable when dealing with highly customised packaging. On fully automated packaging lines, bags are often created from single wound sheeting – folded, welded, filled and sealed on-site. 

When intricate or unique shapes are needed, such as additional gussets or a new shape for a specific product, single wound sheeting offers the flexibility required. These can sometimes compromise the bag’s strength at the seams – and this is where skirt side welds come into play. They reinforce the bag’s structure, compensating for any potential weaknesses at the seams, or adding structural integrity without copious amounts of material.

Uses for skirt side weld bags

Skirt side weld bags find themselves in use in practically every industry. Their versatility makes them suitable for a wide range of purposes, from protecting goods during transit to maintaining the freshness of dry, longlife foods. Here are just a few examples:

Heavy duty mailer bags

When it comes to mailing heavier items like books or hardware, durability is paramount. You also need to keep books and hardware dry in transit – and skirt side weld bags excel in this regard. When made from heavy duty polythene, even weighty contents are securely packaged, minimising the risk of damage in the post.

Inner packaging for longlife foods

Moisture is the enemy of preserved goods. And so, maintaining the quality of dry foods requires a totally watertight seal. Skirt side weld bags offer an excellent solution for this purpose – keeping all your favourite snacks and pantry staples in tip top condition. You’ll find everything from panko breadcrumbs to dried fruit and nuts in skirt side weld bags (as well as the aforementioned crisps!).

Medical packaging

The medical industry demands packaging solutions that are sterile. Skirt side weld bags offer the necessary strength and seal reliability for medical packaging, including sterilised instruments, dressings and surgical equipment.

Read more: How To Choose Medical Packaging

The unique welding method and versatility of skirt side weld bags makes them a valuable choice for industries where product integrity is all that matters. Whether you need to protect heavy goods during shipping, keep those tasty roasted peanuts fresh, or secure medical supplies – skirt side weld bags offer the strength and seal reliability that standard bags can’t match.

These watertight polythene bags provide peace of mind, leaving you safe in the knowledge that your items are protected from the moment they are sealed in. If your packaging supplier can’t give you that – then maybe it’s time to talk to us…

Get polythene packaging that works

Professional packaging solutions, custom-designed for your business. Get a quote now, or call us on 01773 820415.