What are plastic bags made from?

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So what are they made from, these bags that you see everywhere?

In a word, polyethylene, or polythene as it is known in the UK

There are several types of polythene used in bag manufacture. These are the Top Three:

  • HDPE is High Density PolyEthylene. It's used to make supermarket carrier bags and the other types of light bags that are usually not transparent.
  • LDPE is its Low Density sister, used to make soft clear bags like the ones used for packs of vegetables and the bags that toys and clothes are usually packed in.
  • OPP is cousin Oriented Polypropylene and makes cellophane (cello bags) that birthday cards are packed in, or food like pasta. It's not as tough as the other two.

A resealable bag made from LDPE

What's the difference?

The two main differences are strength and transparency.

You know how tough supermarket carrier bags are, even though they are incredibly thin. That's HDPE.
The LDPE transparent plastic bags, although strong, are not quite as tough as carrier bags.
Most bags made from OPP are intended for attractiveness rather than strength.

Apart from strength, the other biggest difference is that LDPE is almost transparent and perfect for clear bags where you want the contents to be visible.

We say 'almost transparent' because the correct term is translucent (lets light through). A single bag may look transparent. Add several more on top of it to make a pile and you will quickly see that the surface beneath becomes less visible as more layers of plastic are added.

A whole bundle looks white, not at all transparent.

OPP is more transparent again with a nice "shiny feel" so it's perfect for packing something to make it look and feel exciting.

See our other articles to find out what polythene is made from.

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