Choosing the right poly bag (film) for your packaging application can be a confusing process. If you’re not familiar with packaging films, you may think they are basically all the same but nothing could further from the truth. A Poly bag can come in different styles, materials, thicknesses, blends, barrier properties and available in loose pack and rolls.

What Are Poly Bags?

Poly bags are flexible packaging bags made primarily from polyethylene. They are used to protect, store and ship products such as food, clothing, hardware, chemicals and consumer goods. Poly bags are available in different sizes, thicknesses and styles, including layflat, gusseted and reclosable bags.

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Bag Types

Poly bags are also known as polyethylene bags or plastic bags. They are commonly used in a wide range of packaging applications, including food packaging, produce, dry goods, magazines, chemicals and products intended for storage or shipping.

The term “poly” commonly refers to polyethylene, the primary material used to manufacture these bags. Packaging bags and films are available in several materials, including LDPE, HDPE, PP and PET, with each offering different levels of strength, flexibility, clarity and moisture resistance depending on the application.

The most common poly bag styles include layflat bags, gusseted bags and reclosable zip-lock bags. Choosing the right material and bag style helps improve product protection, storage efficiency and packaging performance.

Types of Plastic Bags

• Layflat poly bags
• Gusseted bags
• Reclosable (zip-lock) bags
• Poly bags on a roll
• Poly tubing
• Anti-static bags

Poly Bagging for Automated Packaging Lines

Many manufacturers use automated poly bagging systems to improve packaging speed, consistency and labor efficiency. Poly bags on a roll are specifically designed for automatic bagging equipment, allowing products to be loaded, sealed and prepared for shipping with minimal operator involvement.

Automated poly bagging is commonly used in ecommerce fulfillment, medical device packaging, hardware, industrial components and retail applications where productivity and repeatability are critical.

If your operation requires higher throughput, Pyramid Packaging also supplies Autobag automatic bagging systems designed to work with poly bags on a roll for efficient packaging operations.

Learn more about our Autobag packaging systems.

Bag Materials

A Poly bag can come in an array of materials that including but not limited to LDPE, HDPE, PP and PET. Variables like the films clarity, oxygen and moisture barrier rates will help decide on which film type is best for your packaging application.

Linear Low Density Polyethylene (LDPE)

These packaging films are inexpensive, have good clarity and often are used to package fresh produce, frozen foods, and baked goods. Artwork can be added to give the produce a customized look.

High density polyethylene (HDPE)

These packaging films are found in many of the same applications as LDPE and LLDPE. It is stiffer and more rigid than many other PE films. HDPE has good moisture barrier properties and is resistant to grease and oils. HDPE is often used inside a box to preserve its contents, such as cereal bags or cake mixes.

Polypropylene (PP)

These films are soft, clear have good moisture barriers and high oxygen transfer rates. Therefore, PP films are commonly used with bakeries and food markets. These films are similar, but less flexible than LDPE films.

Polyethylene Terephthalate (PET)

PET films are durable, heat resistant films with very good oxygen barrier properties. When PET films are laminated with metal foil (MET PET), it will increase the oxygen-water barrier and block UV rays. Metalized films for flexible packaging are essential when the product requires extra protection to ensure a longer shelf life. MET PET films provide protective properties for food requiring restricted visibility.

Frequently Asked Questions

What are poly bags?

Poly bags are flexible bags made from polyethylene used to protect, store and ship products.

What are the most common types of poly bags?

The most common types include layflat bags, gusseted bags and reclosable zip-lock bags. Each style is designed for different product shapes and packaging requirements.

What materials are poly bags made from?

Most poly bags are made from polyethylene materials such as LDPE, LLDPE or HDPE. Other flexible packaging applications may use polypropylene or PET films.

About Pyramid Packaging
Established in 1968, Pyramid Packaging is a value-added supplier of flexible packaging films, equipment & services. We create value by working with clients who need help in selecting and customizing their packaging films.

Browse our full range of poly bags — including layflat, gusseted, reclosable and custom options — to find the right bag for your application.

Pyramid Packaging can customize your plastic packaging films & barriers according to your blend, size & graphic design. Call us at 847-272-3400, fill out our Contact Us form, or [email protected].