Stop guessing at stretch film specs. This guide explains 10 essential terms—from gauge to pre-stretch—so you can choose the right film, boost efficiency, and cut costs. Read now to master your material selection.

Ever feel lost reading a stretch film specification sheet? What’s the real difference between “80 Gauge Blown Film” and “20 Micron Cast Film”? And how can “Pre-stretch” directly impact your bottom line? Choosing the wrong film doesn’t just waste money—it can lead to load collapses, damaged goods, and safety hazards.

Understanding the term is the first step to making smart, cost-effective purchasing decisions. We’ve broken down the key concepts into a simple guide.

In this part, you will learn:

• The DNA of Stretch Film: Material & Structure (Cast vs. Blown, LLDPE, Co-extrusion)
• Measuring the Muscle: Performance & Testing (Gauge, Pre-stretch, Strength Tests)

Part 1: Material & Structure — The “DNA” of Stretch Film

This is all about what the film is made of and how it’s built, which determines its core characteristics.

1. Stretch Film (or Stretch Wrap): The Core Concept

• The Core Definition: A highly stretchable plastic film made primarily from Polyethylene (PE). It secures loads not with adhesives, but through Elastic Recovery—the physical force it exerts as it tries to return to its original, unstretched state after being stretched. This creates a tight, unifying hold.

2. Blown Film vs. Cast Film: Your Ultimate Choice Guide

The manufacturing process is the most fundamental differentiator. Here’s a quick comparison to make the choice clear:

特徴	Blown Film	Cast Film
Process	Like blowing up a balloon	Like making a pancake
Key Strength	耐パンク性	耐引裂性 & Clarity
Best For	Loads with sharp edges or protrusions	Most applications; the versatile, high-performance choice
Noise Level	Noisier when unwinding	Quiet operation
明瞭性	Higher haze (less clear)	High gloss (excellent clarity)

The Bottom Line: While blown film is a specialist for sharp loads, cast film is the preferred, most versatile choice for the majority of packaging applications. All YD PACK films are produced using advanced cast film technology for superior all-around performance.

3. LLDPE: The Magic Behind Modern Stretch Film

• The Core Definition: Linear Low-Density Polyethylene (LLDPE) is the primary resin used in modern, high-performance stretch films.
• Why It Matters: LLDPE provides the outstanding toughness, stretchability, and strength that make high pre-stretch levels and a secure, tight hold possible. It’s the foundation of today’s high-efficiency films.

4. Co-extrusion: The Power of a Multi-Layered “Sandwich”

• The Core Definition: An advanced manufacturing process that merges two or more different raw materials through a single die to create a multi-layered film.
• The Core Value: This “sandwich” structure allows different layers to specialize, combining benefits like high strength and high cling into one superior film. YD PACK utilizes sophisticated 5-layer co-extrusion technology, where each layer is precisely engineered to achieve the optimal balance of strength, toughness, and cling, resulting in a film that outperforms simpler single-layer alternatives.

Part 2: Performance & Testing — Measuring the “Muscle”

This section covers the key metrics used to objectively measure a film’s capabilities.

5. Gauge vs. Micron: Don’t Get Tricked by Thickness

• The Core Definition: Both are units for measuring film thickness.
  • Gauge is an imperial unit.
  • Micron is a metric unit (1 micron = 0.001 mm).
• The Conversion: 1 Gauge = 0.254 Microns. For example, an 80 Gauge film is approximately 20 Microns thick.
• Pro Tip: Thickness is a basic cost indicator, but it’s not the whole story. Don’t fall into the “thicker is better” trap—a high-performance, thinner film can often outperform a cheaper, thicker one, saving you material and money.

6. Pre-stretch & Elastic Recovery: The Dynamic Duo for Cost Savings

• Pre-stretch: The process of mechanically stretching the film to a predetermined ratio (e.g., 250%) before it is applied to the load, using a stretch wrap machine.
• Elastic Recovery (Film Memory): The film’s ability to try and return to its original state after being stretched. This is the force that keeps the load tight.
• The Synergy & Cost Value: Pre-stretch is the method; Elastic Recovery is the engine. Pre-stretch can increase film yield by 200-300%, dramatically reducing your cost per wrap. Elastic Recovery ensures that the stretched film maintains constant, tight force on the load, preventing it from loosening during transit.

7. Tensile Strength vs. Yield Strength: What “Strong” Really Means

• Tensile Strength: The maximum force a film can withstand before it breaks. It answers “how strong is it at its breaking point?”
• Yield Strength: The stress level at which the film begins to deform permanently and cannot return to its original shape.
• Practical Meaning: For stretch film, we care more about a film’s ability to handle high tension while staying elastic (high tensile strength), not just its ultimate breaking point. A film with high tensile strength can be pre-stretched highly without snapping.

8. Dart Drop vs. Elmendorf Tear: Puncture vs. Tear Resistance

• Dart Drop: A standard test that measures a film’s 耐パンク性 by dropping a weighted dart onto it. This is a key strength of Blown Film.
• Elmendorf Tear: A standard test that measures a film’s 耐引裂性—the force required to propagate an initiated tear. This is a key strength of Cast Film.
• The YD PACK Advantage: Thanks to our cast film process and Nano 55-layer structure, YD PACK films show exceptional tear resistance, effectively preventing “zippering”—where a small nick turns into a long tear during shipping or handling, which compromises the entire load.

9. Cling: The Secret to a Self-Sealing Wrap

• The Core Definition: The property that makes the film stick to itself (without adhesives) but not to the products being wrapped. This creates a secure, self-sealing hold.
• The Technical Point: YD PACK films are formulated with excellent inherent cling for standard conditions. For challenging environments like winter or cold storage warehouses, we offer specialized grades with added tackifiers to ensure reliable, long-lasting performance without unwinding.

Conclusion: Turn Knowledge into Savings

Understanding these core terms allows you to see beyond the basic specs: from the fundamental cast film genetics, to the performance-enhancing 55-layer co-extrusion; from the direct cost-saving power of pre-stretch, to the transport-safe assurance of high tear resistance. Every term translates directly into packaging performance and cost control.

At YD PACK, every technological choice is made with one goal: to provide you with the optimal balance of performance and value.

Ready to Put This Knowledge to the Test?

We’ll help you select the perfect YD PACK film for your specific loads. Get a free, no-obligation sample and see the difference that engineered performance makes.

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