Glass to Plastic Conversion
Discover the pros and cons of glass versus plastic packaging and how to successfully convert your brand from glass to plastic packaging.
By: Berlin Packaging Specialist
Date: September 29, 2022
Consumer packaged goods companies face multiple decisions prior to launching a new or revamped product. One of those decisions involves the packaging material, such as glass versus plastic.
As consumers and policymakers increasingly scrutinize the merits of packaging, it's critically important for brand owners to evaluate all facets of their packaging materials. Let's compare glass and plastic packaging substrates, looking at their advantages and drawbacks.
Glass is transparent, heat resistant, has excellent barrier properties, and will not react chemically or physically with the product. Consumers like glass packaging for its premium appearance and feel, product quality, reusability, and recyclability.
But glass is heavy, and it adds to freight costs. Because of its weight, fewer glass containers can be shipped per truckload — both inbound and outbound (pack out) — than plastic containers.
Glass breakage on filling lines can result in considerable downtime for cleanup prior to restart. Breakage is also a concern for consumers, especially children.
Glass capacity remains tight in North America and around the globe. As a result, about 25–30% of glass packaging is imported into the U.S. Lead times are longer for glass than plastic packaging. Glass containers from overseas carry the cost burden of premium ocean freight surcharges and rates, and glass packaging from China is subject to a 25% tariff.
While glass can be infinitely recycled, its recycling rate in the U.S. is about 33%, comparable to PET and HDPE containers (29%). In states with bottle deposit laws, glass recycling rates are higher (63%) than in non-deposit states (24%). Darker glass typically contains more recycled content.
Plastic packaging is lightweight and generally less expensive than glass. PET provides clarity similar to glass. Clarifiers can be added to PP to improve clarity between the container surface and the product inside (e.g., ketchup), but some opacity or milkiness will remain. Opaque milk jugs are made of HDPE, and the material can be easily colored (e.g., laundry detergent bottles).
Hot-fill PET plastic bottles typically can be filled up to 185 degrees Fahrenheit, but testing is always recommended to see if it will work for a specific product.
Brand owners have multiple options in the shapes and sizes of plastic packaging, while glass sizes and contours are limited. In addition, many blow molders are available throughout North America to produce plastic packaging, enabling the manufacturer to be closer to the filling operation. This proximity minimizes fuel and freight costs.
Glass manufacturing has fewer locations, increasing the likelihood that the distance between the manufacturer and the customer may be an issue.
Due to plastic waste and environmental pollution, some consumers and groups have negative perceptions of plastic packaging. But life-cycle analyses have shown that PET and HDPE packaging with 25% PCR is more sustainable than glass packaging with 25% PCR because of less fossil fuel use and greenhouse gas emissions.
With our vast expertise in custom tooling, global sourcing, quality assurance, structural package design, life cycle assessment, sustainable packaging, and branding strategy, Berlin Packaging possesses the know-how to efficiently and economically change your packaging substrate to improve your bottom line.
Converting from Glass to Plastic
For brand owners looking to move from glass to plastic packaging, the first step is to gain insights from their target audience. How will it impact the brand reputation, consumption or usage, and other touchpoints?
The switch from glass to plastic packaging is not a simple 1:1 replacement. Brand owners should examine several parameters — fill temp, package/product interactions, product shelf life, container size/footprint, type of plastic material, labeling, neck finish, closure, line equipment, and more to ensure they have a smooth changeover.
Because of the larger wall thickness of glass, plastic packaging that holds the same amount of product as glass is typically smaller — about 70–80% of its counterpart's size. That means the plastic package will require a new label and closure and will have a different footprint on the store shelf.
Many glass containers use a metal lug-style closure. Since most plastic containers feature a threaded neck, they cannot accommodate a lug closure. The existing cap applicator for glass containers may require adjustments for plastic packaging.
Moving from glass to plastic packaging is not as straightforward as it may seem. It requires much thought and effort, which will pay dividends in the long run. Partnering with a material-neutral packaging supplier like Berlin Packaging can help brand owners objectively assess the pros and cons of making the switch from glass to plastic packaging.
To support our customers in their conversion from glass to plastic packaging, Berlin Packaging has developed an evaluation tool that assesses a variety of factors — material cost, recyclability, shipping, lead time, carbon footprint, consumer preference, etc. — to help guide and inform the decision-making process.