Most bags and packaging film are made from one of three plastics. They look alike at a glance and behave quite differently, so choosing the right one is most of what makes a bag fit for its job.
Two of them, HDPE and LDPE, are kinds of polyethylene, which is what "polythene" means. The third, PP, is polypropylene: a different polymer, used where its clarity or heat resistance is wanted.
What is HDPE?
High-Density Polyethylene. It is strong for its weight, so a thin HDPE film carries a surprising load, and it is the crisp, rustling film most shopping bags and many garbage bags are made from. It is stiffer than LDPE and stretches less.
What is LDPE?
Low-Density Polyethylene. It is softer, more flexible and stretchier than HDPE, and can be made clear. That makes it the usual choice for food bags, garment bags, liners and general packaging film, where the bag has to give rather than split and the contents should be visible.
What is PP?
Polypropylene. It is not polyethylene at all, though it is used for similar things. PP film is very clear and crisp and stands more heat than polyethylene, so it is used where a product needs to be shown off or packed warm.
HDPE vs LDPE vs PP
| Property | HDPE | LDPE | PP |
|---|---|---|---|
| Full name | High-Density Polyethylene | Low-Density Polyethylene | Polypropylene |
| Is it polythene? | Yes | Yes | No: a different polymer |
| Feel | Thin, crisp, rustles | Soft and smooth | Crisp and glossy |
| Flexibility and stretch | Lower | Higher | Lower |
| Stiffness | Higher | Lower | Higher |
| Clarity | Usually cloudy or coloured | Clear to slightly hazy | Very clear |
| Heat resistance | Moderate | Lower | Higher |
| Typical uses | Shopping bags, garbage bags | Food bags, garment bags, film and liners | Clear display and food packaging |
Which is right for your packaging?
Start from the job, not the material: what goes in the bag, how heavy it is, whether it must be seen, whether it will be printed, and how it will be handled. Strength for weight points to HDPE; softness, stretch and clarity to LDPE; sparkle and heat resistance to PP. Thickness (gauge) matters as much as the material.
If you are not sure, tell us what you are packing. Specifying the film is part of what we do.
What we make from them
See all polythene products, or how the film is made in our factory.