Three images in one showing a bottom weld machine and finished bag samples

Bottom Weld Polythene Bags Explained

What is a bottom weld polythene bag?

Machine image of our in-house bottomweld machine producing a blue polybag
A bottom weld polythene bag is simply a polythene sack. It is made from a flattened polythene tube, this type of film is referred to as LFT in the industry. This tube is then passed through a machine which is sealed by a heated bar after a certain length of film has been passed through it i.e. the length of your bag. The bag is then cut from the remaining tube two to five millimetres after the seal. This type of bag can’t have tape or glue but if you heat seal the top of your bag as well, you’ll have yourself an air tight bag.

Benefits of bottom weld polythene bags

The biggest benefit of these bags is the potential size they can be made to. As the machine seals at the bottom you can feed as much polythene film through as you like before the seal. This means that the length of your polythene bag can be huge. So far we’ve made bags with lengths going up to 2.5mtr. There is a minimum draw of 100mm that you should be aware of however.

Another benefit is the strength of the bag. The heated bar leaves a 2mm seal at the bottom of the bag which in turn allows it to hold a lot of weight, we can even produce a double weld bag for extra strength.

A further significant benefit of this type of bag is the fact that we can run two or three polythene reels at once, reducing our conversion time and making our delivery date to you much faster.

Who are bottom weld bags useful to?

Bottom weld bags are ideal for a vast range of things including pet food, bedding, industrial wipes, building supplies, pharmaceuticals, or anything that needs protection from the elements. Let’s not forget the film can also be printed beforehand so if you need your company logo, some warning text, or a custom message then we can provide that. We currently print up to 8 colours. For more details on printing to polythene film check out our printed mailing bags.

If you need any more information regarding any of the above, or you would like a quote, please get in touch with our friendly team who will be happy to help.