Cardboard vs Corrugated: Why you are probably mis-identifying industrial packaging materials.
Ever since you were a child, you’ve known that cereal comes in cardboard boxes. So why do we use the term “cardboard” to refer to corrugated material as well?
If we had a dime for every time someone called us asking for a cardboard box when what they really want is a corrugated box… Well, we could put a lot of dimes into a corrugated box. (Note: we couldn’t put many dimes into a cardboard box, because it would soon break.)
We understand – “corrugated” isn’t as common a word, and it isn’t as easy to pronounce. And we’re not actually sticklers for words. But for the sake of elucidating the packaging process, we thought we’d write a blog to clarify the difference once and for all. And while we’re at it, we’ll explain different types of corrugated material as well, so you can understand everything that goes into constructing your corrugated box.
What is Cardboard?
Cardboard (also known as paperboard, fiberboard, or carton), is what cereal boxes are made from. It is a thick paper that is often lined with wax or another material to make it water resistant. Though cardboard is suitable for lightweight applications and many small consumer goods, it does not provide real structural strength and cannot protect products from impact. For this reason, it is seldom used in crate-manufacturing. You wouldn’t protect a piece of machinery with the same stuff you use to protect your Cheerios™.
What is Corrugated?
Corrugated material is made up different layers of material, forming a structurally sound building material that, unlike cardboard, can take weight and protect against impact.
The three layers are: an inside liner, and outside liner and a fluting layer. Usually the fluting is between the inside and outside layer, but you can also find corrugated that has fluting on the outside.
Below, we list the most important aspects of corrugated construction to keep in mind when designing packaging:
The two most common types of liner for corrugated are Kraft paper and test paper. Kraft paper – what you know of as the brown paper that often lines basic corrugated boxes – is made from softwood pulp, making it very strong and very easy to print on. Test paper is made from recycled material and for this reason is not as strong but is cheaper than Kraft. You’ll often see test paper used on the inside of a box and Kraft paper on the outside, though other configurations exist, as well as other paper types.
The weight of paper is identified using GSM, or grams per square meter. An 80 gsm paper means that if you weighed a square meter of it, it would weigh 80 grams. So a liner that is 125gsm Kraft paper, would be written as 125K, while 125gsm test paper, would be denoted as 125T. These abbreviations help packagers and their clients get specific about what kind of corrugated they are getting.
The thing that makes corrugated different from cardboard is the fluting layer. Fluting is literally “corrugated,” meaning it is made in grooves that give it structural stability. These fluting layers come in different sizes and are measured by grooves per foot.
Common flutes sizes are A, B, C, E, and F. A flutes are wider and stronger, while E and F flutes are smaller and not as strong. E and F flutes, however, provide a better surface for printing.
Common flute sizes including liners:
A flute: 5mm
B flute: 3mm
C flute: 5mm
E flute: 1.5mm
F flute: 1.2mm
A common way to denote a single-wall corrugated would be to put the fluting between two types of paper. For instance 125K/C/125T would be 125gsm Kraft paper, a C flute layer, and then 125gsm test paper.
Single- to Triple-Wall
Corrugated is generally named by its thickness according to the number of walls that it contains. Single wall corrugated has only one layer of fluting, double-wall has two, and triple-wall corrugated has three.
Double wall corrugated is the most common, as it is used in most consumer corrugated applications like shipping boxes and moving boxes. It is generally said that a well-constructed double-wall corrugated box could hold material up to 30kgs, if it was handled properly.
Triple-wall corrugated, on the other hand, can hold weights of up to 50kgs. We often use triple wall corrugated on wooden bases because the strength that corrugated provides is similar to wood, and yet it contributes less to the overall weight. For this reason, triple-wall corrugated is one of the most common corrugated materials used in the industrial packaging industry.
Many double- and triple-wall boxes use combinations of fluting sizes to maximize strength while also providing a good printing surface. Common combinations for double-wall are BC flute, and EB flute. BC (B and C flutes layered together) is more durable but supports only basic printing, while EB fluting (E and B flutes together) provides good strength and offers a great surface for printing, because the E fluting is on the outside of the box.
The perfect corrugated for the job.
We hope this article has given you more perspective on this nearly ubiquitous material we call corrugated. Next time you’re looking for a packaging solution for a product, you’ll have more perspective on the options available and the way the box is constructed. Get in touch with us today to discuss the different options with a packaging expert and to find the perfect corrugated material for your application.
This article is the first in a series of articles about the uses of corrugated in packaging. Next we’ll discuss different types of fluting and liners that can be used in combination for different effects. And then we’ll show you how corrugated boxes are tested using different methods to determine their strength. We’ll discuss specifically the edge crush test and the burst (or Mullens) test. So stay tuned!