What Is Shrink Wrap? (And How It Differs From Stretch Wrap)

Shrink wrap is a plastic film that is placed loosely around a product and then heated, which makes it contract tightly to the shape of whatever is inside. The result is a sealed, close-fitting skin that protects the item, holds multiple pieces together, and shows clearly if anyone has opened it.

The word “shrink” is doing the work. The film arrives slack and becomes tight through heat, which is precisely what separates it from stretch wrap — a different material that does the opposite job in a different way, and the confusion between the two is the most common question in warehouse packaging.

How shrink wrap works

The film is manufactured by stretching it in one or both directions whilst warm, then cooling it in that stretched state. That locks a memory into the plastic. When it is heated again, the molecules relax back towards their original arrangement and the film contracts.

The process on the floor is three steps:

1. Enclose the product. The item is placed inside a bag, a sleeve, or a sheet folded around it. At this stage the film is deliberately loose — roughly 10% larger than the product is a common guide, because film needs slack to shrink into.

2. Seal it. The open edges are joined, usually with a heat sealer that melts and fuses them, or by using a pre-made bag that needs only one seal. The seal must be complete or the film will not draw tight evenly.

3. Apply heat. A heat gun for low volumes, or a shrink tunnel — a short heated conveyor — for anything continuous. The film contracts within seconds and, on cooling, holds its new shape rigidly.

Two variables govern the result: temperature and dwell time. Too little of either leaves the film loose and wrinkled; too much burns holes or distorts the product. Both are set once for a given film and product and then left alone, which is why tunnels produce more consistent results than a person with a heat gun.

Shrink wrap vs stretch wrap

They are frequently used interchangeably in conversation and they are not interchangeable in use.

The short version. If you are securing a pallet for transport, you want stretch wrap. If you are protecting or presenting an individual product or a multipack, you want shrink wrap. Plenty of operations use both daily and never for the same job — cases shrink-wrapped as retail units, then those cases stacked on a pallet and stretch-wrapped for the journey.

Shrink film materials: PVC, POF and PE

Three film families dominate, and they are not substitutes for each other.

PVC is the cheapest and the oldest. It gives excellent clarity and it has real drawbacks: it emits hydrogen chloride when heated, which needs extraction and is unpleasant in an enclosed space, it leaves residue on sealing equipment that requires regular cleaning, and it is not generally approved for direct food contact. Its use has declined steadily for those reasons.

Polyolefin is the modern default for retail packaging. It is stronger, clearer under stress, approved for direct food contact, and it produces almost no fumes. It costs more than PVC and the gap is small enough that most operations have moved regardless. It is available in cross-linked grades for extra strength and in anti-fog grades for chilled food where condensation would otherwise obscure the product.

Polyethylene is the heavy-duty option. Thicker, tougher and less clear, used where protection matters more than presentation — industrial bundling, beverage multipacks, building materials, and large or awkwardly shaped items. Its recycling stream is also the most established of the three.

Choosing between them: food contact or a clean environment means polyolefin. Heavy, sharp or industrial goods mean polyethylene. PVC remains a cost choice for non-food retail items where ventilation exists and nobody minds cleaning the sealer.

Gauge, clarity and seal strength

Gauge (thickness). Shrink film is specified in gauge or in microns. Common retail films sit between 45 and 75 gauge (roughly 12 to 19 microns); heavier industrial applications run to 100 gauge and above.

Thicker film is stronger and costs more, shrinks more slowly, and needs more heat. The practical approach is to start at the lower end for your product type and move up only if you are getting splits or punctures in handling. Over-specifying gauge is a common and invisible cost — it buys protection nobody is testing.

As a rough guide: small light retail items at 45–60 gauge, general boxed goods at 60–75, heavy or sharp-cornered items at 75–100, and industrial bundling above that.

Clarity. Matters where the product is sold on a shelf and does not matter at all where it is going into a carton. Do not pay for optical clarity on goods nobody will see through the film.

Seal strength. The seal is where shrink wrapping fails. A weak or incomplete seal lets the film pull open as it contracts. Seal strength depends on the sealer temperature, the dwell time and the cleanliness of the sealing wire — which is the main practical argument against PVC, because the residue it leaves degrades seals until somebody cleans the blade.

Shrink ratio. Films are specified by how much they contract, and in which directions. A film that shrinks in both directions conforms to irregular shapes; one that shrinks mainly in one direction suits sleeving and banding.

The benefits of shrink wrap

Protection. A sealed skin keeps out dust, dirt, moisture and handling marks through storage and transit.

Tamper evidence. Shrink film cannot be removed and replaced. A broken seal is visible immediately, which is why it is standard on pharmaceuticals, food and anything where interference matters.

Unitisation. Several items held as one — a three-pack, a boxed set, a case of tins. It creates a single thing to scan, count and pick, which has a real effect on order picking accuracy.

Moisture resistance. A complete seal on all sides, which stretch wrap does not provide.

Presentation. Tight, clear, professional. For anything sold on a shelf or arriving with a customer, the appearance is part of the product.

Low material cost. Film is inexpensive per unit and adds almost no weight, which keeps shipping costs down compared with rigid packaging.

It conforms to awkward shapes. Irregular items that would need a custom box can be wrapped as they are.

It reduces pilferage. Sealed multipacks are harder to break into quietly than loose items.

Applications by industry

Food and beverage. Multipacks of cans and bottles, trays of chilled goods, produce, and bakery items. Polyolefin for anything in direct contact, often in an anti-fog grade so chilled products stay visible.

Pharmaceuticals and healthcare. Tamper evidence is the primary reason rather than protection. Cartons, bottles and medical devices, where a broken seal must be obvious to the person opening it.

Retail and ecommerce. Boxed goods, gift sets, books, cosmetics, electronics. Protection through the supply chain plus a presentable arrival, and a barrier that stops sets being split on a shop floor.

Industrial and building materials. Heavy polyethylene bundling for timber, pipe, insulation and fixings — protection from weather and handling rather than presentation.

Print and publishing. Books, magazines and stationery, where dust and edge damage are the enemies.

Distribution and 3PL operations. Kitting, multipacking and repackaging as a value-added service, frequently done to a client’s specification on receipt rather than by the manufacturer.

The equipment, and a quick how-to

What you need at minimum: a roll of centre-fold film or pre-made bags, a heat sealer, and a heat source.

At low volume, an impulse sealer and a heat gun. Inexpensive, entirely manual, and fine for tens of units a day.

At moderate volume, an L-bar sealer — a hinged arm that seals two edges in one motion — feeding a small shrink tunnel. This is the common step up and it changes both speed and consistency.

At high volume, an automatic or semi-automatic wrapper with an integrated tunnel, fed by conveyor.

The method, with a heat gun:

1. Cut or select film roughly 10% larger than the product in each direction. Too tight and it will not shrink cleanly; far too loose and you get wrinkles and folds.
2. Enclose the product and seal the open edges, holding the sealer for the full dwell time rather than releasing early.
3. If the product traps air, pierce the film once with a pin. Trapped air forms a bubble that the film cannot shrink against.
4. Apply heat evenly, moving continuously and keeping the gun 100–150mm away. Work the corners and edges first, then the flat faces.
5. Let it cool before handling. The film sets as it cools, and moving it warm distorts the finish.

The common faults and their causes. Wrinkles usually mean insufficient heat or too much film. Holes mean the heat was held in one place too long. A seal that opens means the sealer was too cool, released too early, or the wire needs cleaning. A milky finish usually means the film was overheated.

Where to go deeper

• What is dunnage — the void fill and cushioning that works alongside it.
• What is a pallet — what stretch wrap is actually for.
• What is order fulfilment — where packing sits in the process.
• What is kitting — the multipacking that shrink wrap usually finishes.
• What is reverse logistics — why packaging that survives transit reduces returns.
• Warehouse processes — the flow this stage belongs to.

The one-line takeaway

Shrink wrap is plastic film applied loosely and then heated so it contracts tightly around a product, giving protection, tamper evidence and a retail-ready finish. It is not stretch wrap, which uses tension rather than heat and secures pallets rather than products — and the film you choose matters, because polyolefin is food-safe and clean-burning whilst PVC is cheaper and neither.

Frequently asked questions

What is shrink wrap? A plastic film placed loosely around a product and then heated, which makes it contract tightly to the product’s shape. It provides a sealed, tamper-evident, close-fitting skin used for individual items, multipacks and cartons.

What is the difference between shrink wrap and stretch wrap? Shrink wrap is tightened by heat and used on individual products and multipacks. Stretch wrap is tightened by tension as it is wound on, needs no heat, and is used to secure pallet loads for transport. They are different materials for different jobs and are not interchangeable.

Is shrink wrap food safe? Polyolefin film is approved for direct food contact and is the standard choice for food packaging. Polyethylene is available in food-grade specifications. PVC is generally not approved for direct food contact and also releases hydrogen chloride when heated, so it needs ventilation.

How does shrink wrap work? The film is manufactured in a stretched state, which gives it a memory. Heating it lets the material relax back towards its original dimensions, so it contracts around whatever it encloses and sets rigidly as it cools.

What gauge shrink wrap do I need? As a guide: 45–60 gauge for small light retail items, 60–75 for general boxed goods, 75–100 for heavy or sharp-cornered products, and above that for industrial bundling. Start at the lower end for your product type and increase only if you see splits or punctures in handling.

What equipment do I need to shrink wrap? At minimum a heat sealer and a heat gun, which is adequate for low volumes. Moderate volumes justify an L-bar sealer feeding a small shrink tunnel, which is faster and far more consistent. High volumes use automatic wrappers with integrated tunnels.

Why is my shrink wrap wrinkled or full of holes? Wrinkles usually mean not enough heat or too much film for the product. Holes mean the heat was concentrated in one spot for too long. Seals that open mean the sealer was too cool, released too early, or the sealing wire needs cleaning.

Can shrink wrap be recycled? Polyethylene film has the most established recycling stream and is widely accepted where soft plastics are collected. Polyolefin is recyclable in principle and less widely collected. PVC is the most difficult of the three, which is another reason its use has declined.

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