Blown vs Cast Stretch Wrap: What Are the Differences & Benefits?

Stretch film (or stretch wrap) is a plastic film typically manufactured from Linear Low Density Polyethylene (LLDPE), and is used for pallet wrapping, bundling and securing. This wrapping of a product or pallet of products with stretch wrap helps to protect the item from damage and loss.

Stretch film has two main methods of application:

• hand stretch wrap
• machine stretch wrap

Additionally, stretch film is made using two main manufacturing methods: blown and cast.

In this article, we’ll explore:

• How cast stretch wrap is made
• The benefits of cast stretch film
• How blown stretch wrap is made
• The benefits of blown stretch film
• The differences between cast stretch wrap and blown stretch wrap
• The use of PCW within cast and blown stretch wraps
• Conclusion: Which is better?

How Is Cast Stretch Wrap Made?

Cast stretch wrap is manufactured using a cast extrusion process. A granular resin is fed into a heated screw barrel, which melts the resin. This melted resin is then fed through a flat narrow slot (also called a die). The sheet of material this creates is then passed over chilled rollers to quickly cool and solidify the film.

The dimensions of the die, as well as how fast the film is pulled away from it, determines the thickness and width of the stretch film.

The Benefits of Cast Stretch Film

This cast extrusion manufacturing process results in cast stretch film having a range of benefits:

• High transparency
• Glossy appearance
• High tear and puncture resistance
• Protects against moisture, gases and aromas
• Consistent thickness
• Available in a range of thicknesses
• Quiet when unwinding
• Consistent cling

How Is Blown Stretch Wrap Made?

Blown stretch wrap is manufactured using a blown extrusion process. Similar to cast stretch wrap, a granular resin (and any additives) is fed into a heated screw barrel, which melts the resin. This melted resin is then blown through a circular die, creating a bubble.

The volume of air blown into this tube stretches the tube/bubble out to the desired width, while the speed at which it is being blown through the die determines the thickness. This air also slowly cools the film, with this slow cooling process being one of the reasons for the film’s hazy and dull appearance.

Nip rollers can then flatten this material into a tube that can be reeled for creating bags and pouches, or it can be slit and then reeled for creating a flat sheet of film.

The Benefits of Blown Stretch Film

This blown extrusion manufacturing process results in blown stretch film having a range of benefits:

• Very high tear and puncture resistance
• Protects against moisture, gases and aromas
• Very durable and tough for increased protection
• Produces less manufacturing scrap
• High level of cling

Stretch film is one of the most versatile packaging products on the market, discover more about the benefits of stretch film.

The Differences Between Cast Stretch Wrap & Blown Stretch Wrap

These processes give cast and blown stretch wrap key differences.

PCW (Post Consumer Waste) Stretch Wrap

No matter which manufacturing method you opt for, Industrial Polythene can provide more environmentally friendly stretch wrap which contains at least 30% Post-Consumer Waste (PCW).

PCW is waste that is left over after it has served its original purpose as a consumer item. By recycling this plastic into new products, we reduce the amount of waste that is sent to landfill or incinerated; disposal methods that are very harmful to the planet and contribute heavily to climate change.

Find out more about our eco-friendly packaging solutions.

Cast Stretch Wrap vs Blown Stretch Wrap: Which Is Better?

With their unique characteristics and properties giving them different advantages, which stretch wrap is better?

If looking at the industry statistics, one would think cast wrap the clear winner, with 70-80% of organisations opting for it.

However it’s also important to consider the application. Cast stretch film is the best choice for some uses, while blown stretch film is the best choice for others.

For example, blown stretch wrap has higher durability and a high tear and puncture resistance. This makes it the better option for wrapping sharp-edged products and heavier loads.

On the other hand, cast stretch wrap is used more for light products and loads stacked on pallets. It’s clarity makes it the ideal choice when you need to scan barcodes and see labels through the film.

Stretch Wrap Solutions

Looking for stretch wrap for your organisation? Get in touch with Industrial Polythene to request a free sample or discuss your requirements and our friendly expert team will help find the perfect solution for you.