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Packaging 101: A Quick Primer on Packaging, Inside and Out

Updated: Jul 31, 2022

A recyclable mailer made me curious about packaging materials. My takeaway: sustainable packaging has a promising future.

A couple of days ago, UPS made a delivery. While opening the Amazon mailer, I wondered about the packaging. Consisting of stiff brown paper stock and quilted baffling, it looked and felt “green.” A glance on the backside confirmed my observation. Emblazoned in boldface were the words: “Recycle this mailer just like a box.” Curious about the baffling, I cut the paper; couched between the two sheets were semi-regularly spaced splotches of foam. Green indeed.

A recyclable mailer with paper torn to show foam splotches within
Recyclable mailer with foam padding. Steven Long

That got me wondering about packaging and the environment. Anecdotally, it seems packaging is becoming greener—meaning recyclable or compostable. A few years ago, a recyclable mailer would have shocked and amazed me. Now, a percentage of the packaging (and the packaging contained within it) arriving at my household is recyclable or compostable.


Taking packaging for granted, I never thought about the types of materials and their sustainability. Thus inspired by this mailer, I decided to explore the world of packaging.


The basics

When I place an online order, the retailer has three levels of packaging to consider.


The first is primary packaging. Also called retail or consumer packaging, primary packaging is the plastic bottle, the aluminum can, the paper sack, or the laminated bag. Packaging at this level has two purposes: protecting and marketing the product. This is where companies do their best to woo consumers by employing textures, shapes, colors, fonts, and words in scrupulously calculated ways. This packaging can also be challenging to open, like thermoformed plastic, which easily cuts fumbling fingers.

The next level is secondary packaging. This packaging groups the product into a stock-keeping unit (or SKU) and protects it during shipment. Think cardboard box. Next to paper, cardboard is a ubiquitous packaging material and has proven to be revolutionary since its invention in the 1800s. Other secondary materials are plastic or wooden crates and trays, cereal boxes, and beer trays.

Tertiary packaging (or bulk or transit packaging), the final level, is about getting the product from A to Z as efficiently as possible. This is where trucks, trains, and cargo ships filled with stretch-wrapped pallets and cardboard boxes come into the picture. Packaging at this level is expected to be handled and seen by employees, not consumers, so it’s unattractive and utilitarian.


Packaging materials

Another thing the retailer needs to determine before completing my order is deciding on the type of packaging material. The choices are many but not all are appropriate. And sometimes, some materials are more practicable than others. The following are some of the more popular packaging materials:

Plastic bottle, flexible lid, glass gar, aluminum can, and cardboard box
Five common packaging materials. Steven Long

  • Paper, paperboard, cardboard Paper is used for labels, bags, and Kraft paper; paperboard is thicker and can be found in milk and juice cartons, cereal boxes, and ice cream containers; cardboard is several times more rigid yet lightweight.

  • PET, HDPE Polyethylene terephthalate (PET) is commonly used for water and soda bottles, household cleaners, and cosmetics. High-density polyethylene (HDPE) is more rigid than PET, so it’s a great choice for bottle caps, shopping bags, and bottles for acids, bleach, and other caustic substances.

  • LDPE, LLDPE Low-density polyethylene (LDPE) is perfect for squeezable bottles, toys, flexible lids, and retail packaging. Linear low-density polyethylene (LLDPE) is more flexible than LDPE, so it’s used in cling and stretch wrap, trash bags, and other instances that call for plastic film.

  • Aluminum Every year 180 billion aluminum cans are produced globally—it’s no wonder they dominate this category. However, aluminum packaging also protects medical devices, medicines, cosmetics, coffee, and other products sensitive to sunlight, moisture, and air.

  • Glass Like aluminum and some forms of plastic, glass can be used and re-melted indefinitely. This is a good thing, given that the US alone produces about 12 billion tons annually. (Sadly, only a quarter of this glass is recycled.) Bottles for alcohol and other liquids account for the majority, while the remainder consists of glass packaging for food, cosmetics, and home décor.

Filling the void

The next step with my order is selecting the void-fill material. For decades, retailers predominantly used Styrofoam, a type of expanded polystyrene, to protect their shipments. And why not? It’s inexpensive, strong, lightweight, water- and bacteria-resistant, moldable, and an excellent shock absorber. It also quickly breaks into smaller pieces, is prone to static electricity—as evidenced by the foam beads that latch onto your skin and clothing—and is nonbiodegradable.

Styrofoam is still used, but fortunately, other kinds of greener void-fill materials are gaining ground:

  • Paper Though not a new invention, paper still works great as a filler. Whether newspaper or dedicated packing paper, it's superb in filling corners and cushioning fragile things, especially when it's crinkled or twisted. It can also be shredded, increasing its void-filling capabilities.

  • Corrugated bubble wrap This is a simple solution to recycling cardboard. Discarded cardboard is fed through a machine that spits out sheets that look more like woven mats than cardboard. When no longer needed, this filler is recyclable or compostable. Though not technically bubble wrap, die-cut Kraft paper has a similar feel and purpose.

  • Cellulose packaging Found in the walls of plant cells, cellulose is the most abundant organic material on Earth. It gives plants their stiffness and helps trees grow tall. For packaging, cotton, hemp, and wood fibers are processed to produce cellophane, a sustainable, biodegradable, and compostable film that is moisture- and oil-resistant. Developed before World War I, cellophane packaging is primarily used for food, cosmetics, and personal care.

  • Cornstarch packaging Corn is the most widely planted crop in the US. One of its many by-products is cornstarch, which comes from fermented corn kernels. The kernels are fed through a mill that pulverizes them and releases dextrose, a sugar starch. Next, the dextrose is fermented in vast tanks, and the end product is polylactic acid, a material as versatile as petroleum-based polymer resins. Resistant to oil, fats, and aromas, cornstarch packaging makes excellent to-go containers for food. It’s also compostable, but only under optimal conditions, which is to say it’ll take months to degrade in your backyard compost bin.

  • Mushroom foam packaging There are two main parts to a mushroom: the fruiting body aboveground and a dense network of mycelium belowground. How dense? Paul Stamets, a recognized authority on mushrooms, suggests one cubic inch of soil can contain up to eight miles of mycelia! Mushrooms grow fast—some varieties, like oyster mushrooms, are harvested in less than four weeks. And they are super easy to propagate. To produce mushroom foam, mycelia are mixed with agricultural waste (like husks or straw from corn, hops, rice, and hemp), pressed into molds, and then placed in a warm, dark room. Within as little as a week, the foam is ready for packaging. On the other end, when it has served its purpose, you can bury it in your flower beds or compost bin. The foam is fully decomposed in less than a month.

Close-up of mushroom foam packaging lying in grass
A biodegradable wine shipping container made by Ecovative Design. Mycobond via Wikimedia Commons

Rosy outlook for green packaging

Nowadays, I’m more subdued when packages containing green void-fill arrive at my door. Still, the child in me loves dissolving cornstarch packing peanuts and running my hands over corrugated bubble wrap and die-cut Kraft paper. And mushroom foam still makes me giddy. I’m a sucker for these kinds of materials.


Setting aside my exuberance for sustainable packaging, it appears my anecdotal observation is accurate. In 2009 this portion of the global packaging industry was worth $88 billion. This year it will surpass $290 billion, and by 2030 it will easily top $467 billion.


What does that mean for me? The days of collecting statically charged Styrofoam peanuts and beads are numbered. Plastic bubble wrap might also disappear, which I’m mixed about. Bubble wrap is an environmental nuisance. It’s also fun to pop—so much so that psychologists publish studies on its stress-relieving benefits.


So, while I might be a tad more stressed down the road, that stress may be tempered by packaging whose final destination is my garden rather than the trashcan.

Further reading

A Guide to Eco-friendly Void-fill.” The Packaging Insider, June 1, 2020.

BrentR. “5 of the Most Common Packaging Materials in the World.” Packaging Blog, March 27, 2017.

Flagel, Jordan. “Mycelium: Using Mushrooms to Make Packaging Materials.” Matmatch, April 3, 2020.

Hartman, Shelby. “Mycelium Technology: What Materials Will Mushrooms Replace?” FreshCap Mushrooms, March 29, 2021.

Nicasio, Francesca. “9 Environmentally Friendly Packaging Materials to Help Your Business Go Green.” noissue, September 13, 2021.

Royte, Elizabeth. “Corn Plastic to the Rescue.” Smithsonian Magazine, August 2006.


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