Plain mylar bags, and custom mylar bags that are printed during the production process, are now the packaging of choice for many consumer products. They are cost effective, take up minimal storage space, are unbreakable and light to ship, and provide a lot of room for branding. Additionally, to make them tamper evident, they can be easily heat sealed with low-cost equipment. Finally, custom printed mylar bags can generally be ordered in low quantities relative to other custom packaging solutions, especially with the advent of digital printing. All in all, it’s easy to see why they are such a popular form of product packaging.

So, what exactly is a custom mylar bag. Mylar has become the generic name for a wide range of plastic bags, but very few are made only from mylar. The truth is that almost every bag is produced with a variety of different films. These individual films have their own special characteristics and are laminated to make up a single compound film designed to provide the best storage medium for the product being sold.

Compound films, specific to the item being sold, are used for a variety for reasons. Some products may need environmental protection from air and moisture exfiltration and infiltration. This would apply to most food products that in addition to a “normal” film, also need a “food grade” layer of film on the inside of the bag. The other extreme are plastic items that are not affected by the same environment factors. A plastic item would typically not be affected by air or moisture which is why most are sold in single film “baggies”. What make a custom mylar bag custom is the ability to laminate various films in various thicknesses to make the perfect protective barrier for the intended product. Additionally, if it’s multi use product like candy, zipper bags can be made with an area above the zipper for heat sealing to make it tamper evident. Another recent innovation is the child resistant custom mylar bag. New zipper designs have made it possible to produce bags that meet the Consumer Product Safety Commission requirements for child resistant packaging.

Compound films are the key to product preservation. Clearly one of the most challenging products to package is cannabis. It has a naturally high level of highly evaporative volatile organic compounds called terpenes These terpenes are what create the distinctive aroma that end users associate with high quality. Additionally, cannabis contains a percentage of water weight that keeps it from being harsh when smoked. If the cannabis dries out on the retail shelf, not only will the smoking experience be bad, but the weight will be less than advertised, which is critical for a product sold by the gram.

Using cannabis as an example, the type of film necessary to keep moisture and terpenes in and air out requires a “tight chain” molecular structure. All films have an Oxygen Transmission Rate (OTR) and Moisture (Water) Vapor Transmission Rate (MVTR/WVTR). What that means is that over time, oxygen and water vapor will work its way through the film material.

Depending on the material, the rate of transmission can vary dramatically. There are several factors that affect transmission, but the two major ones are the thickness of the material and the alignment and configurations of the molecular chains that make up the film. Typically, films with a tight chain molecular structure are more difficult to manufacture and as a result, cost more, but have superior moisture and vapor transmission rates. Since films are sold by weight, to make a cost-effective bag the ideal solution is to use the right thickness of the tight molecular chain film and laminate it with thicker, lower cost, loose molecular chain film so that the end result is a bag that has a good feel in the hand, but also performs well as a barrier bag that protects the contents.

While barrier bags look simple, a lot of engineering goes into determining the best mix of films necessary for a particular product. There are always tradeoffs in the cost versus performance equation. That means that while two different bags may look and feel the same, the actual performance can be quite different. This is a prime example of “cheaper is not always better”. While cheaper packaging may lower the overall cost of the product, a lower quality bag will contributes to product degradation and unhappy customers that won’t buy again. Investing in a slightly more expensive custom mylar bag will typically insure a much better end user experience and lead to repeat sales.