Bags with a lip? No, they’re not particularly chatty. But you have almost certainly used one, without even realising it. Ever had an easy-open mailer bag arrive through your letterbox? Yep – that was a bag with a lip! But there’s so much more to them than postage; like evidence bags for police, specimen bags for medical use, banking bags, and tamper-proof pouches protecting high value items.
So, let’s start off with… what exactly are they?
What are bags with a lip?
At its simplest, a polythene lip bag is just like any other polythene bag – but one side of the opening is deliberately manufactured to be longer than the other.
Read more – How Are Polythene Bags Made?
This extended flap or “lip” makes a world of difference to how the bag is used. It creates a convenient tab that makes the bag incredibly easy to open, even when your hands are full or you’re wearing gloves. Very important for evidence collection, dropping in a medical specimen, or handling a delicate, high value item.
That lip also provides a dedicated, strong surface for sealing the bag shut – and the options for sealing are plenty: with tape, a heat sealer, or an adhesive, self-sealing strip manufactured onto the bag itself.
The benefits of bags with a lip
The beauty of the design for bags with a lip is the sheer practicality of it.
Filling standard polythene bags can be a fiddly, frustrating experience – especially if you’re packaging your goods manually. Imagine you’re a bank cashier trying to get a fistful of freshly counted £20 notes into a fiddly bag without a lip. Annoying? Yes! Now imagine you’re a forensics expert on a crime scene, wearing gloves, a mask, and a full cleanroom suit. Annoying isn’t the half of it; fumbling evidence could destroy a criminal investigation, and a bag with a lip makes the job so much easier.
That’s because the extended lip acts as a natural opening, giving you something to grip and pull apart. It’s a small act of design kindness that makes the packing process faster.
The sealing is the main benefit. The lip gives you a clean, unobstructed surface for a secure closure. Many bags with a lip feature a strip of adhesive on the lip itself, often covered by a removable paper liner (lip and tape bags). You simply pack your items, peel off the liner, and fold the lip over to seal the bag shut. It is quick, secure, and can be designed to be tamper-evident, making it perfect for sensitive contents. But heat sealing, simple staples, or just some sticky tape will do the job, too – and if security isn’t a major concern, the lip can simply be tucked into the opening over the contents, for rudimentary but effective wrapping.
The lip also makes the unpacking experience far more pleasant. A bag with a lip is so much easier to open than a standard bag, thanks to that unobstructed surface – there’s a lot of area to grab, tear, or peel away, and you can see very clearly if it’s been tampered with or compromised before use.
Common uses for lip bags
Bags with a lip have found a home in a huge range of industries – some you’ll be familiar with, and others we hope you’ll never have to be!
Bank bags and night deposit bags
One of the most classic uses for a polythene lip bag is in the banking sector, where security and tamper-evidence are paramount. Bags with a lip can be used as night deposit bags, where cash and cheques need to be dropped off securely at a bank after hours. The tough polythene and secure sealing system, often combined with tamper-evident features, provide an extra layer of protection and accountability. They are also used internally, for transporting cash and valuables between branches, and can be printed, written on, and labelled for tracking and sorting.
Evidence bags and tamper-proof bags
In law enforcement and forensic science, the integrity of evidence is everything. Compromised physical evidence means dangerous criminals can potentially walk free. Keeping everything safe from the point of collection is the core concern. And so, bags with a lip are the industry standard for evidence bags.
They are designed with tamper-evident seals, and any attempt to open one leaves visible damage. Printing and labelling areas provide a clear chain of custody, ensuring that evidence cannot be tampered with at any stage without it being immediately obvious. The same principle applies to other tamper-proof bags used in secure logistics.
Learn more about temper-evident packaging
Mailer bags and ecommerce
If you’ve ever bought clothes, books, or other non-fragile items online, you have almost certainly received them in mailer bags, and almost all of these are bags with a lip. Ecommerce giants love them because they are lightweight, durable, and incredibly fast to pack.
A self-adhesive strip on the lip allows a packer to fill the bag and seal it in seconds, making them a perfect fit for busy fulfilment centres. They are also opaque, offering privacy for the contents within.
Medical device and biological specimen bags
Medical professionals work in a high-pressure environment, so any packaging for the medical devices they use in life-or-death situations must be intuitive to use, easy to open, and provide quick access in the heat of the moment. Bags with a lip are all of this and more.
Polythene is durable but non-shedding, so no particles or fibres contaminate the device when torn open, and tamper-evidence once again gives a clear indication of whether the device is good to use.
Specimen bags are an excellent application for bags with a lip, too. They’re easy to open and seal with gloves, and provide protection for healthcare professionals and the specimens themselves during transit and handling.
Get custom polythene lip and tape bags, from NPF Packaging
The polythene lip bag is a perfect example of how a small, thoughtful design feature can create a packaging solution that is efficient, secure, and easy to use. Need help ordering custom polythene bags with a lip? Get in touch now. Contact us or call 01773 820415.