Corrugated Box – The Master Guide

stay of corrugated boards

When discussions about packaging arise, it’s easy to get confused.

We’re all used to hearing the standard word “cardboard” in this context, and generally, we don’t think much further than that.

However, when you’re thinking about your product and what kind of packaging it needs, it comes more into focus.

Cardboard isn’t just one kind of packaging material; there’s more to it.

Cardboard is one type of material, and corrugated cardboard is another. They are often confused for one another but serve different purposes depending on the product.

Example of corrugated box
Source: PakFactory

Corrugated cardboard has a lot of benefits that make it an excellent packaging choice.

This post will explore the differences between cardboard and corrugated cardboard and some of the benefits and use cases for this packaging.

This post can help you decide what kind of packaging you need and how working with corrugated packaging companies can help ensure your product packaging is an excellent experience for your customers each time.

We’ll first look at the corrugated definition, its history, and some of the key differences between a corrugated box and cardboard boxes.

Corrugated Boxes – An Overview

The conventional cardboard box has 3 fiberboard layers in its structure. 

The outer layers are called linerboards, and the wavy layer of paper sandwiched in between the linerboards is called flute. 

In some cases, to add extra protection to the products, corrugated sheets can be doubled-up, combining different grades of fluting. 

The everyday corrugated box is the most common as a shipping and mailing option. The walls provide the much-needed protection for even the roughest handling, and the material is relatively cost-effective. 

Most companies use corrugated boxes to efficiently ship and deliver enormous amounts of products over long distances. In contrast, some companies opt for printing on their corrugated boxes.

Although these boxes are ubiquitous within our everyday lives, little is known about them.

Corrugated vs. Cardboard – What’s the difference?

As we delve further into corrugated packaging and its uses, it’s essential to set the scene first and talk about the key differences between cardboard and corrugated and why it’s crucial to distinguish between the two.

Cardboard is generally made of thick paper stock or heavy paper pulp.

It’s typically used for smaller product packaging and containers.

It can also be used as structural support in packaging to keep items from losing their shape during transit.

Corrugated boxes and cartons are not made from the same materials.

Made from three layers of paper; corrugated boxes consist of an inside liner, outside liner, and fluting that runs between the two.

Corrugated packaging is used for shipping boxes, as corrugated sheets are sturdy and durable!

Key differences between the two include:

  • Raw materials used for the packaging
  • Weight: Corrugated is lighter than cardboard
  • Durability
  • How the packaging is used

Knowing the difference between the materials is essential in deciding what kind of packaging will work best for your products.

If you’re thinking about using corrugated boxes, a corrugated packaging company can work with you on the design and prototype process to create the right option for you.

We’ll now look at why corrugated is such a popular choice across different industries.

In this post, we discuss everything you need to know related to corrugated packaging.

The Corrugated Industry

Whether your company is shipping out large volumes of packages or sending a few products, corrugated boxes are among the best options.

The reason why it’s so popular is because of its durability, stability and versatility.

You can trust that products will remain safe in the packaging, and it can be designed in a way that customers love.

It’s a win-win packaging material!

This has become more apparent during the pandemic as e-commerce sales continue to rise.

Corrugated packaging is used across the retail industry and is becoming more needed as e-commerce sales shoot up.

In 2021, the e-commerce industry is projected to increase to 2.14 billion shoppers, leading to a higher demand for this kind of packaging in retail.

We’ll now take a look at some of the types of paper grades that go into creating corrugated boxes.

Types of Paper Liners

Kraft Liners

Manufactured from softwood trees, Kraft paper consists of 70-80% “virgin” chemical pulp fiber, which results in a top paper grade that is very stiff and durable. Kraft paper is the most sustainable option out of all the types of paper available. However, Kraft paper is also the most costly option.

Example of kraft liners
Source: PakFactory
  • Brown Kraft may vary in natural brown color depending on the different fibers used, the pulping process, and the location of the paper mill
  • White Top Kraft is very strong and affordable and offers excellent printing characteristics
  • Mottled Kraft aka Oyster Kraft, similar to White Top Kraft with a mottled appearance
  • Fully Bleached White is a white Kraft liner with a natural look that is put through an additional bleaching process to create a white surface. This paper grade is not as environmentally friendly as unbleached kraft. 

Test Liners

Test paper is a less costly option than Kraft. 

There is a higher percentage of recycled-fiber content, resulting in a less durable paper liner. The higher recycled fiber content also makes the paper more difficult to print on. Which makes it very common to use Test paper as the inner linerboard of a corrugated box.

  • Test 2 is partly recycled liner paper
  • Test 3 is fully recycled liner
  • White Top is a white-coated recycled liner
  • Oyster is a mottled test liner

Flute Paper

  • Semi Chem is made using virgin fibers and a neutral sulfite semi-chemical process
  • Waste Based Fluting is made from 100% recycled fibers

Flutes Grades

Corrugated box fluting refers to the arches sandwiched between the linerboard. 

These flutes are made of paper just like the liner boards. The difference lies in the way they are constructed.

Flutes are essentially corrugated shaped liner boards that provide cushioning, strength and compression resistant qualities. 

Let’s take a look at some of your thickness options.

  1. Liner board: This is essentially the ‘face’ of the fiberboard sheet. Corrugated sheets are glued on to this.
  2. Single face: This refers to a single corrugated fiberboard. It is glued to one flat sheet of linerboard and shows the fluting on one side.
  3. Single wall: This is probably what you’re most used to seeing, as this is fluted fiberboard glued between two sheets of linerboard. Single-wall corrugated boxes are a lighter form of packaging and considered one of the “weaker” options.
  4. Double-wall: This uses three sheets of linerboard and two corrugated fiberboards in between rather than just one.
  5. Triple wall: The amounts are increased, with four sheets of linerboard and three corrugated fiberboards in between. These can withstand heavier weights, going up to almost 300 lbs!

Single Wall

Single-wall corrugated box styles vary in material strength and durability. This can be tested with the Edge Crush Test, as discussed later in this guide.

Single-wall corrugated boxes can carry weights from 23 ECT to up to 55 ECT. It weighs less and “weaker” single-wall corrugated boxes may hold up to a minimum weight of 20 lbs

A-Flute – 1/4” is the first type of corrugated flute. This flute grade has the highest protection and cushion qualities. Very good at handling compression and stacking, it is often used to package fragile items.

B-Flute – 1/8” this type of flute appears much thinner than others, but do not let its appearance fool you. B-Flute is quite strong, and it is typically used for counter displays and canned food products. 

It also has a flatter surface for higher quality printing and is excellent for die-cutting. 

B-Flute has excellent puncture and crush-resistance properties while also consuming less space. It has excellent all-round performance for all types of packaging, but is also commonly used as padding, dividers, partitions, and other forms of additional packing material.

C-Flute – 3/16” is flexible and one of the most versatile flute grades in corrugated boxes. It has average crush resistance, stacking strength, and printing properties. You have likely seen this type used for shipping boxes but also used to package glass, dairy, and furniture products.

E-Flute – 1/16” is not typically used for shipping. As one of the thinner flute grades, E-Flute is often used as an alternative for paperboard folding cartons. 

E-Flute is also designed to be thinner and more condensed to reduce the outer box dimensions, which saves on storage space. E-Flute has excellent compression strength, crush resistance, and a relatively flat surface for high-quality printing applications. You may use E-Flute for cosmetics, fragile glass, ceramics, and other small and delicate products.

F-Flute – 1/32” has protective qualities similar to E-Flute but with an even smoother surface for high-quality printing. It is common for you to use F-Flute for clamshell packaging to use in the US fast-food industry. On the other hand, Europe has adopted this grade of corrugated fluting as a standard option for specialty and retail packaging.

SINGLE WALL
Max. Weight Box/Contents (lbs.)Min. Burst Test (lbs. per sq. in)Min. Edge Crush Test (lbs. per in. width)
2012523
3515026
5017529
6520032
8025040
9527544
12035055

Double Wall & Triple Wall

Because there are at least two walls of corrugated sheets in this style of corrugated box, double-wall, and triple-wall boxes are, of course, more durable. The downside to this is that the box is less flexible. 

However, in some cases, this trait may be necessary for certain products.

Double wall boxes have three sheets of linerboard with two corrugated fiberboards in between.

Triple-wall boxes have three stacked corrugated sheets and four liner board facings. 

Although it is possible to form many different combinations of double-wall or triple-wall corrugated boxes, here are a few standard double-wall combinations found within the industry:

AC Flute is a combination of the two most protective corrugated grades. 

This is an excellent option if you need extra protection in preparation of the harsh shipping and handling processes. 

With A-Flute stacking and compression resistance, this combination also makes for an excellent storage option.

BC Flute is an excellent all-round performer, this combination provides high-level transit protection and is most often seen in shipping boxes.

EB Flute provides excellent transit strength and protection, while the outer E-Flute allows for an excellent high-quality printing surface.

DOUBLE WALL
Max. Weight Box/Contents (lbs.)Min. Burst Test (lbs. per sq. in)Min. Edge Crush Test (lbs. per in. width)
8020042
10027548
12035051
14040061
16050071
18060082
TRIPLE WALL
(minimum puncture test, oz. per in. of tear)
Max. Weight Box/Contents (lbs.)Min. Burst Test (lbs. per sq. in)Min. Edge Crush Test (lbs. per in. width)
24070067
26090080
280110090
3001300112

Quality Control Tests

Corrugated boxes are common for shipping and mailing purposes. 

They are subject to different kinds of stress and impact during the packing, shipping, and storage process. 

Corrugated packaging aims to resist damage as much as possible to protect the products inside. 

There are different ways to test the strength of corrugated material. But which test should you use when selecting material for your corrugated boxes?

Edge Crush Test is one of the essential tests for corrugated packaging. 

As the name implies, force is applied perpendicular to the edge of the corrugated board until it buckles. 

The results provide manufacturers the confidence for the material to have the strength and durability required to handle heavy loads and stack resistance.  

The resulting value is shown in pounds per linear inch of load-bearing edge and is reported in ECT ratings. 

32 ECT is the most commonly used for corrugated material. 

The Flat Crush Test is similar to the Edge Crush Test. 

This test applies force directly on a surface area of the corrugated fiberboard until the flute flattens and compromises its structure. 

This test determines the compression and stacking resistance of the corrugated board required to carry heavy loads.

The Burst Test, otherwise known as the Mullen Test, challenges the durability of the corrugated fiberboard’s surface. As the Flat Crush Test tests compression resistance, the Burst Test determines the amount of force required to puncture the linerboard. The resulting value is given in pounds per square inch. 

200# means 200 pounds per square inch of force applied to the face of the linerboard. 

Water Absorption Test, otherwise known as the Cobb Test, determines the level of moisture that the material is able to withstand and maintain its structural integrity. 

Measuring the absorbency of the box surface is also important because it may affect the printability of the box. 

On the back surface, the same test indicates how well the liner will adhere to the fluting. 

The test begins by setting a sample of the paper material above an open container with a specific measurement of liquid. The container is flipped, allowing liquid to absorb into the material for a certain amount of time before being removed and examined. 

Ring Crush Test measures the compression of paper and board materials. A strip of paperboard with a standardized length and width is formed into a ring. Force is applied perpendicular to the paper’s edge until it buckles. 

Box Maker’s Certificate

Have you ever picked up a box from Amazon or Uline, checked the bottom and found a circular stamp that looks like a nutrition facts label? 

That is a box maker’s certificate, also called a BMC. It is a convenient and efficient way of describing some quick specifications about the box.

There are 2 versions of box maker’s certificates: ECT-Rated BMC and the Mullen-Rated BMC.

There are a couple of visible differences but in essence, these two certificates provide the same information.

The Box Manufacturer is indicated in the outer ring. This is the company that is responsible for manufacturing your box.

Board Construction is the information displayed directly under where it says box certificate. 

This information indicates the thickness and construction of the box walls by stating whether the box is single-wall, double-wall, or triple-wall.

Minimum Combined Weight Facings is the total weight of the linerboard used before the full linerboard is cut and made into boxes.

Size Limit is the maximum outer dimensions of the box. This section is useful to know for storage and shipping purposes.

Gross Weight Limit is the maximum weight allowed for the box and the items in it.

City & State is the final information stated on the box at the bottom of the label. This is where the box is constructed and shipped from.

Benefits of Corrugated Packaging

Corrugated cardboard and corrugated boxes have seen enduring popularity because of the many benefits they offer and the relatively low cost of production.

Some of the main reasons for their popularity include:

Protection: Corrugated is one of the best packaging options available for those seeking to protect their items during transit. It can handle the impacts of being moved around and shipped, and the cushioning offers a lot of support.

Durability: Corrugated boxes are durable because of their protective features.

The boxes themselves withstand a lot of impact without damaging the products inside, and it also serves as a barrier to the elements for products.

Environmentally-friendly: Sustainability has become increasingly important, and packaging especially. Corrugated boxes are made of recycled fibers.

They are also easily recycled, making them a better contender for sustainable packaging.

Customizable: Because of the many options available for raw materials and their environmental-friendliness, corrugated boxes are the best option for those looking for bespoke packaging, including printing.

The shapes and thickness are easily customized, alongside the graphics and surface printing.

But what are some of the industries that corrugated packaging works best for?

What Industries Benefit from Corrugated Boxes?

Many industries benefit from using corrugated packaging, especially e-commerce.

Depending on the size and shape of the packaging chosen, shipping and mailing can be more manageable.

As discussed, corrugated cardboard and corrugated boxes can withstand a lot of the wear and tear that occurs during shipping, making them the safest option.

E-commerce businesses benefit immensely from corrugated packaging, especially during the strange times we have been living in.

With the reliance on online shopping growing exponentially, businesses have been opting for corrugated packaging to ensure their products arrive on their customers’ door steps in pristine condition.

Furthermore, corrugated packaging offers great versatility in printing capabilities allowing their brand to stand out in the mail rooms of their customers.

example of ecommerce packaging
Source: PakFactory

Corrugated is also the best option for sustainability and recycling, as discussed above.

Customers want to be loyal to brands, but brands need to demonstrate some commitment too.

By choosing sustainable packaging, you can build an immense amount of trust with the customer and add lots of value to your brand narrative.

Corrugated packaging enables you to develop customer relationships while doing good for the planet.

Corrugated boxes are eco-friendly, recyclable packaging options that look great too –  a total win-win.

In fact, recycled corrugated is used to make clay-coated news back (paper grade), thereby giving it another life!

Here are some examples of corrugated packaging successes we’ve worked with to give you a better idea of what the end product looks like and what corrugated boxes can be used for.

1canoe2: High-quality branded corrugated boxes

Working with 1canoe2, Pakfactory developed unique packaging that was true to their brand and continued shipping products safely.

The digitally printed corrugated boxes were printed incredibly fast while allowing the brand total creative freedom to design the packaging as they saw fit.

The result? A beautiful package that created a fantastic experience for customers as soon as they received their products.

This is just one example of all the different ways corrugated packaging can be used, but you can find more inspiration for corrugated packaging here to find the right fit for your product.

example of 1canoe2 packaging
Source: PakFactory

Corrugated packaging offers a host of benefits at a relatively low-cost.

You can have a lot of creative freedom in designing the packaging precisely as you wish with this material, which can be a lot of fun.

With a good understanding of corrugated packaging, businesses have the power to establish brand credibility and an exceptional customer experience.

Contact a packaging specialist today to find out more about how you can use corrugated packaging for your product!

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