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What Is Corrugated Cardboard?

Elisabeth Natter
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Any business that ships or receives merchandise has most likely used a corrugated box. The fluted middle section of this special folded cardboard forms a highly durable container that protects products during shipping. It can be manufactured into many sizes and is reusable and recyclable.

Chances are you see boxes made of corrugated cardboards almost every day. Whether in the local grocery store or used as packaging for the products you send or receive for your business, corrugated cardboard is a staple in the shipping industry. But what makes it so special and highly utilized?


Corrugated cardboard is a multi-layer packing material used for protecting merchandise during shipping. The middle layer is folded, or corrugated, to provide extra strength.

What Makes Cardboard Corrugated?

Corrugation is simply the process of putting folds into another material such as metal, or in this case, a sturdy paper. A strong, fibrous paper known as Kraft paper is run through heated corrugating rollers that consist of a series of ridges and grooves that fold the paper into flutes. The result is similar to when you fold a piece of paper for use as a fan. This folded paper is known as the medium.

The size of the flute roller can be changed to alter the size of the corrugated medium. Corrugated flute standards range in size from an A flute to an F flute. Each medium is a different thickness and will support a different weight of product based on the number of flutes within the medium. For example, a B flute cardboard medium is composed of approximately 47 flutes per foot, is about one-eighth inch in thickness and was originally designed for holding canned goods.

The Structure of Corrugated Cardboard

After the flute is created, the corrugated paper medium is then sandwiched and glued between two layers of Kraft liner paper to create a sturdy corrugated card. This board can then be printed on and manufactured into boxes of any shape or size as might be required for shipping or use in a pop-up display.

Benefits and Uses in Shipping

Corrugated cardboard is widely used for shipping for several reasons. The arched flute design of the board's interior provides an architecturally sturdy material that stands up to the rigors of transportation. It also provides a unique air cushion for added protection. If specified in the manufacturing process, outer liner papers can be specially treated with resins to create an additional moisture vapor barrier to protect especially sensitive materials such as books, food or electronics that need to be protected from excess moisture.

As part of the manufacturing process, some boxes have colorful designs, logos and marketing materials printed directly on the box. For example, a sturdy box of vegetables with colorful labeling can be immediately set out in the produce section once it is delivered and the container becomes part of the marketing display without an additional effort or expense.

Benefits to the Environment

Another reason that corrugated cardboard is so popular is that it is highly recyclable. It is manufactured using trees, which are a renewable resource, and recovered cartons. The industry claims an over 93% recovery rate for its products and aggressively works to promote a sustainable industry. Corrugated cardboard boxes can easily be folded down to lie flat for the next storage or shipping need or recycled through community programs.

Disadvantages of Corrugated Cardboard

Despite its environmental friendliness and the wide variety of corrugated cardboards available to product manufacturers, this type of packaging material may not be ideal for every situation. Although it features a sturdy design, extremely heavy items or large pieces of machinery may not travel well in cardboard cartons. As cargo shifts during transportation, heavy items may break through the packaging and even cause damage to the item being shipped.

Similarly, without special treatment to the outer surface of a corrugated box, the material is subject to weather and moisture. While some products are currently being used in the industry to deal with these shortcomings, there is ongoing research to improve applications that will make corrugated boxes both water-resistant and fire-resistant.