Packaging engineers rarely get credit when a tray of fresh meat, a dairy cup, or a sterile medical device arrives intact — but the thin, transparent film sealed across the top of that container is doing more engineering work than most consumers realize. This film, known as lidding film, is a purpose-built barrier material that seals trays and containers made from plastic, aluminum, or paperboard.
What Is Lidding Film?
Lidding film is a flexible, heat-sealable top-web material used in tray-sealing and thermoforming lines. Once heat-sealed to a pre-formed tray, it creates an airtight, tamper-evident closure that protects the contents from contamination, moisture loss, and oxygen exposure. Unlike rigid lids, lidding film conforms to the tray geometry, uses less material per pack, and allows for full-surface branding and product visibility — which is why it has become the default sealing method across fresh food, healthcare, and personal-care packaging.
Film Structure and Barrier Chemistry
Most high-performance lidding films are co-extruded multilayer structures rather than a single plastic sheet. A typical build combines:
| Layer Function | Common Materials | Purpose |
|---|---|---|
| Seal layer | EVA, LLDPE, ionomer | Bonds to the tray flange (PE, PP, PS, or PET substrates) |
| Barrier layer | EVOH, PVDC | Blocks oxygen and gas transmission |
| Structural/outer layer | PA (nylon), PET, PE | Provides puncture resistance, clarity, and printability |
| Anti-fog coating | Surfactant additive | Prevents condensation fogging under refrigeration |
The EVOH or PVDC barrier layer is what separates true lidding film from ordinary shrink wrap. It is this layer that keeps oxygen and nitrogen exchange low enough to preserve color, moisture, and shelf life in refrigerated meat, seafood, and dairy packaging.
Key Technical Specifications
When evaluating a lidding film, converters typically compare films against standardized test methods so results are apples-to-apples across suppliers. The table below reflects the type of data sheet used to qualify a high-barrier lidding film for fresh food applications:
| Property | Unit | Test Method | Typical Value |
|---|---|---|---|
| Thickness | μm | — | 25 |
| Tensile Strength (MD/TD) | MPa | ASTM D882 | 70 / 70 |
| Elongation (MD/TD) | % | ASTM D882 | 80 / 80 |
| Shrinkage at 100°C | % | ASTM D2732 | 15 / 15 |
| Oxygen Transmission Rate | cm³/(m²·24h·0.1MPa) | — | 15 |
| Water Vapor Transmission Rate | g/m²·24h | — | 20 |
| Haze | % | ASTM D1003 | 4 |
| Clarity | — | ASTM D1746 | 90 |
| Gloss @ 45° | — | ASTM D2547 | 100 |
| Roll Width | mm | — | 300–650 |
| Roll Length | m | — | 1600 |
Data reflects typical values for high-barrier lidding shrink film as published on the Lidding Barrier Shrink Film product page. Actual values vary by structure and gauge; request a current certificate of analysis for lot-specific data.
How Lidding Film Is Sealed to a Tray
Lidding film is applied using tray-sealing or thermoforming equipment, where the film unwinds from a roll, is heated at the seal head, and is pressed onto the tray flange under controlled temperature, dwell time, and pressure. Because these three variables interact with the tray substrate and the seal-layer chemistry, most suppliers provide parameter guidance rather than a single fixed setting. Two closure styles dominate the market:
Peel seal — a controlled, weaker bond that allows the consumer to open the pack by hand without tearing the film.
Weld seal — a permanent, high-strength bond used where tamper evidence and leak resistance are the priority, such as liquid-containing trays.
Industry Applications
| Industry | Typical Use Cases |
|---|---|
| Food & Beverage | Fresh meat and seafood, ready-to-eat meals, dairy, produce, baked goods |
| Healthcare | Sterile medical device trays, surgical kits, diagnostic trays |
| Personal Care | Disposable cosmetics, wet wipes, skincare single-use trays |
| Retail & Consumer Goods | Hardware kits, housewares, refill packs |
See our full breakdown of use cases by sector on the Application page.
Choosing the Right Lidding Film
Specification should start with the product being packed, not the film itself. Fresh, oxygen-sensitive proteins need a low OTR barrier film; steam-table or microwave-ready meals need heat-resistant, oven-safe films; and refrigerated produce needs strong anti-fog performance to keep shelf appeal at retail. Key questions to work through with a supplier include:
What tray substrate (PE, PP, PS, PET) will the film be sealed to?
Does the pack need a peelable or a permanently welded seal?
What shelf-life target and OTR/WVTR ceiling does the product require?
Is microwave or oven use required downstream?
Does the brand require recyclable or mono-material film for sustainability compliance?
Sustainability Considerations
Regulatory and retailer pressure has pushed lidding film development toward recyclable and mono-material structures that maintain barrier performance while simplifying end-of-life recycling. Buyers evaluating sustainable options should ask specifically whether a film is recyclable in existing polyethylene or polypropylene streams, or whether it requires specialty collection — the distinction materially affects whether a package can legitimately carry a recyclability claim.
About Zhejiang Zhongcheng Packing Material Co., Ltd.
This article is published by Zhejiang Zhongcheng Packing Material Co., Ltd., a manufacturer of barrier shrink film and lidding film based at No. 1, Taishan Road, Huimin Street, Jiashan, Zhejiang, China 314100. Our technical and R&D background is detailed on our Technical Innovation page, and our manufacturing history is documented under Development History. To learn more about our company and quality standards, visit About Us, browse our full Product range, or read industry updates on our Blog.
Frequently Asked Questions
Is lidding film the same as shrink film?
No. Shrink film wraps and contracts around a whole product; lidding film is a flat, heat-sealed top-web applied to a single tray or container opening.
Can lidding film go in the microwave?
Certain formulations are microwave- and oven-safe; this must be confirmed against the specific film's temperature rating before use.
What causes seal failure?
The most common causes are incorrect seal temperature, insufficient dwell time, contamination on the tray flange, or a mismatch between the film's seal layer and the tray substrate.
