Plastic Bag Trivia: What’s A Nurdle?

Don’t worry, you read the last word in the title correctly and my computer’s autocorrect didn’t make it up! Nurdle is a bizarre word relating to plastic bags but it can also be used when talking about cricket and even toothpaste. However, I bet you don’t know what it means.

Making Plastic Carrier Bags

How many times a week do you use a plastic carrier bag? Do you just use them once for the weekly food shop, or do you carry them around every day on your lunch? They are so commonplace it’s easy to take them for granted, but to get to the bottom of the nurdle mystery we need to look at how plastic bags are made.

To make a plastic bag you need an extruder you can pour polyethylene pellets into. What’s an extruder, I hear you ask? It’s a large pumping machine about the size of a cow which contains a screw that mixes and melts all those polyethylene pellets.
After being flattened the plastic is called lay flat film. Later on lay flat film can be folded, heat sealed or perforated, for example a plastic carrier bag is made by folding the lay flat film over and heat sealing the edges.


Where does the word nurdle come into it then? Remember the raw plastic pellets that are poured into the extruder? Well, this pea shaped feed specially used for plastics manufacturing and packaging also has another name, the wonderfully weird ‘nurdle’.

So what about cricket and toothpaste, what have they got to do with nurdles? The word nurdle certainly gets about a bit and has ended up meaning all sorts of strange things.

In cricket a player is said to have hit a nurdle when they score a run by gently nudging the ball into an empty bit of the field. Doesn't quite sound as good as a scoop and it probably scores lower as well.

As for toothpaste, think of all those adverts you see for it on TV or in the shops. There’s nearly always an iconic wave shaped blob of toothpaste resting on a toothbrush, and it’s the shape of this blob which is called a nurdle. Of course real life is never as perfect, my toothpaste rarely comes out nurdle shaped.
While the plastic film is inflated it can be treated in certain ways to produce different types of carrier bag. Our varigauge plastic carrier bags are thicker around the base and handle, so a cooling pad is applied to the section of the tube where plastic needs to be thicker. By cooling the plastic quicker a thicker gauge is produced.

The Extrusion Process

Once the resin is ready a brave worker pinches the molten plastic, ties a rope around it and attaches it to a pulley. This pulley hauls the plastic film up in a big tubular tower which eventually tapers off and gets squeezed flat through two nip rolls. By piping air up into the tube the plastic film does not collapse and its shape can be changed. For wider plastic products more air is piped in to expand the film.
Plastic bags are all made out of polyethylene, a kind of resin. Roughly 80 million tons of the stuff are produced every year, no wonder plastic bags get everywhere!

The molten resin ends up in a big vat and at this stage masterbatch can be added to change the colour of the plastic. Masterbatch is the industry term for coloured plastic pellets, so if you want to make a red bag you add red masterbatch. You don’t need to use much masterbatch as it makes up only 5% of the molten plastic in the vat.
One other definition for the word nurdle, it can mean: ‘to gently waffle or muse on a subject which one clearly knows little about’. Hopefully you’ll agree that this article has not been a nurdle!

Until next time,


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