Cast vs blown stretch film: how they differ and when to use which
Two ways to make the same kind of film
Both types are made mainly from linear low-density polyethylene (LLDPE), often with metallocene grades (mLLDPE) and a share of recycled material in the core layers. The difference is how the melted plastic is turned into film.
- Cast film. The melt is pressed through a flat die onto a chilled roll. It cools in a fraction of a second. Fast cooling gives a clear film with an even thickness.
- Blown film. The melt is pushed through a round die and blown up into a large bubble that cools slowly in the air before it is flattened and wound. Slow cooling gives a stiffer film with different strength properties.
Modern machine films are built from several layers: an outer cling layer, a slip layer that stops rolls and pallets sticking together, and core layers that carry the strength. More layers give the producer more freedom to tune the film for a job.
How they behave on the pallet
| Property | Cast film | Blown film |
|---|---|---|
| Stretch | Softer, stretches further | Stiffer, stretches less |
| Film yield | More pallets per kilo | Fewer pallets per kilo |
| Memory and load retention | Lower: holds through correct pre-stretch and layers | Higher: pulls back harder after stretching |
| Tear resistance | Medium | High |
| Puncture resistance | Medium | High |
| Clarity | Clear, glossy | Hazier, less gloss |
| Noise when unwinding | Quiet | Loud |
| Price per roll | Usually lower | Usually higher |
Two more points that the table does not show:
- Cling varies by product, not only by process. Many modern multi-layer films cling on one side and slip on the other, so pallets do not stick together. Check the data sheet rather than assuming.
- Clarity matters more than it sounds. Warehouses and retailers need to scan labels through the film.
Cast film is the usual choice for machine wrapping. Blown film is the specialist: chosen where toughness and load retention matter more than yield.
Which loads suit which film
Cast film usually fits:
- regular, well-shaped loads such as cartons on a full pallet,
- high-speed lines and powered pre-stretch carriages,
- customers who want to use less film by running it at its rated pre-stretch.
Blown film often fits:
- loads with sharp edges or corners that can puncture film,
- irregular loads where the film meets points and protrusions,
- applications where tear resistance matters more than film yield.
These are rules of thumb. Thickness, the film’s rated pre-stretch, the wrapper and the wrapping pattern often matter more than the process the film was made in.
Hand film and machine film
Both processes are used for hand film and machine film. The bigger difference for film use is how the film is applied. Hand film is made to stretch at the force a person can apply. Machine film is made for pre-stretch between rollers, to ratios no one can reach by hand, so the same weight of machine film usually wraps more pallets. Running machine film by hand gives poor stretch and high film use. Read more in the right pre-stretch and types of pallet wrappers.
Do not compare films by price per roll
A cheaper roll can cost more per pallet. Two films with the same thickness can perform very differently, and a well-built thinner film can beat a poorly built thicker one once both are stretched on the customer’s wrapper. The fair comparison is grams of film per pallet on the same load, at the pre-stretch each film is designed for, with a check that the load still holds.
That is the test Palletseal runs at the customer’s wrapper: the current film first, then yours, on the same load, followed by load stability tests. See also the right pre-stretch.
Questions we often get
Is cast or blown stretch film stronger?
It depends on what you mean by strong. Blown film usually resists punctures and tears better. Cast film can be stretched further and reaches its strength through correct pre-stretch.
Why is cast film quieter?
Cast film unwinds smoothly from the roll. Blown film is noisier when it unwinds, which some warehouses notice on high-speed lines.
Which is more common?
Cast film. It is the usual choice for machine wrapping of pallets: it is cheaper to make, clear, quiet and wraps more pallets per kilo. Blown film is chosen where toughness and load retention matter more.
Does blown film hold the load better?
Blown film has more memory: after it is stretched it pulls back harder, which helps hold awkward or heavy loads. Cast film reaches its holding force through correct pre-stretch and the right number of layers.
Which film is better for high pre-stretch?
Cast film is generally made to run at high pre-stretch on powered pre-stretch carriages.
Can I switch from blown to cast film?
Often yes, but test it on the same load. Check the film used per pallet, how the film handles corners, and that the load still passes a tilt test and a containment force check.
