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Material Basics

Barrier Packaging

Barrier Packaging is used for products that require the contents to be protected or separated from the surrounding environment. Barrier packaging serves to prevent transmission of things such as water vapor and oxygen. These are the two most common elements that can degrade or significantly shorten the useful life of a packaged product. Other threats include light or extreme temperatures. Most barrier packaging relies on the inner side of the material to be heat sealed to itself to create a strong hermetic seal.

Barrier Films

In the early 1900’s a clear film was developed for packaging. Using cellulose from wood pulp, this film was known as cellophane. It was 100% biodegradable. Then, during the 1950’s, a variety of plastics were invented to replace cellophane. Plastic films continue to be developed to achieve unique barrier qualities. Special properties can also be created by layering dissimilar films or chemically mixing them before a film is produced.


Layers of different materials are often bonded together, resulting in a barrier material with a specific purpose in mind. The outer layer of a laminate may be selected for its desirable printing qualities, barrier qualities, or both. The innermost layer of a laminate, often referred to as the sealant layer, is most commonly polyethylene (PE) or some chemically similar material.

Foil Laminates

Often, when a near perfect barrier is required, a layer of aluminum foil will be included. This foil layer is typically .000285″ to .0003″ thick and sandwiched between other materials. While an extremely effective barrier, the aluminum layer adds significantly to the cost of a laminate.


A less expensive (and slightly less effective for barrier purposes) alternative to an aluminum layer is clear film that has an even thinner layer of aluminum deposited onto it. While application methods vary, think of this as aluminum sprayed onto the surface.


Tyvek® is a unique material that is often used to make pouches for the health care industry. While it is a “breathable” material, medical grade Tyvek® is an excellent barrier to microbial penetration. It is often used for sterile pouches that are peeled open in a laboratory or an operating room. Flex-Pak is authorized to purchase Tyvek® directly from its manufacturer, DuPont.

Packaging Options

Flexographic Printing

If printing is desired on a package, this must be done on a roll of film or laminate before it is formed into a finished product and filled. Flexographic printing is typically used. Rolls of laminate are printed with a pattern that repeats as required by the package size. Printing can range from simple one color work up to 8 or 10 colors. Our limit at Flex-Pak is 8 colors.

Printing can be simple solid colors printed adjacent to one another (line printing) or process printing, which produces photographic images. Process printing uses millions of tiny dots that are aligned with one another to produce the photographic likeness of what we see around us. An almost infinite number of colors can be achieved with flexographic process printing.


A basic pouch consists of two layers of material heat sealed together to make a three side seal (3SS) package. They are also called pillow pouches. A seal, ranging from 1/4″ to 1/2″, is produced by heat to weld the edges together. There are many features that can be added to a basic pouch.


A package that is made with a heat sealed seam in the center of the back side is a bag. Think of snack food packaging, like that commonly used for potato chips.

Closure Options

Closure by Filler

When finished bags or pouches are ordered, our customers will usually fill them and seal them with a constant heat sealer. Hot wire or impulse sealers do not provide a good enough seal to insure a perfect barrier quality. If one molecule can get through an inferior seal, so can millions more.

Closure by End User

Double faced tape can be used by end users to permanently or temporarily seal a pouch. Using the proper tape and design, this can be an effective barrier.

Recloseable by End User

Reusable closures are usually accomplished with zippers. Convenient repeated use of a product can justify the additional expense.


Expandable Packaging

Pouches and Bags can be made with side gussets. Also, stand up bottom pouches can be produced, allowing them to stand on a retail store shelf and also to consume less space in a consumer’s pantry when the pouch is filled.

Hang Holes

When packages of product will be hung on a retail display, a hang hole can be punched into a wide top seal. Many shapes are available from which to choose.

Tear Notches

A small notch can be placed in the side or the end of a pouch or bag for easier opening by the end user.


Pouches can be designed to have a fitting sealed in place. Fittings can serve a variety of purposes ranging from a screw cap pour spout to tube attachments, and on and on.


An offset of material on a front and back panel of a pouch is often referred to as a lip. This feature is sometimes desired for ease of manual filling. A typical lip offset might be about 1/8″.

Do you need more information? Call us now at 630-761-3335, send us an email or Request a Quote!