What’s a Flute? How to Choose the Best Board Strength and Board Type for your Packaging

You’ve got your graphics and design ready. But now it’s time to decide on two things; your board strength and board type. What do these words mean and which one do you go with? It’s one of our most asked questions. We get it; it can be a real head-scratcher.

A close-up shot of cardboard boxes

It’s hard to talk packaging without knowing more about board strength and board type (flutes). So, pull up a chair and let’s discuss more about the most essential part of corrugated material.

Board Strength

In some of our box sizes, you’ll find you need to choose your board strength. Board strength refers to the Edge Crush Test (ECT). This is a true performance test and is directly related to the stacking strength of a carton. It is usually listed as an ECT value (for example 32 or 44). If you are shipping a product that weighs between 25-40 pounds, a 32 ECT single-wall carton should be sufficient, in most cases. You will need to use 44 ECT for anything over 40 pounds and up to 95 pounds.

Board Type

There will also be times you will be asked to choose your board type (especially when entering a custom size). Corrugated fiberboard (sometimes called cardboard) is comprised of three fiberboard layers; two linerboards sandwich a middle sheet that is in a wave-shaped pattern known as flutes. These flutes give strength and structure to boxes, and also serve as a protector, insulator and cushioning device. Each flute size has a useful function, from shipping strength to reducing storage space and improved printability.

How do you know which flute size to choose?

E-flute — Lighter

Our most popular flute size is also the smallest flute we offer. (Thickness of 1/16″)  E-flute has a relatively flat surface, which makes it ideal for high quality printing. This super thin profile reduces outer box dimensions and can help save on storage space. It also provides the greatest crush resistance making it a good choice for glass, delicate instruments, cosmetics, liquor, food, high graphic displays, pet supplies and point of purchase boxes. You will see this type of board used in our Earlock Mailer, One Piece Folder, Tuck Top Mailer and Full Overlapping Carton.

B-flute — Middle-weight

B-flute is our second most used flute, being a good alternative to E-flute when wanting to support heavier items. With a thickness of 1/8″ and shorter flutes, this type of box still provides a rigid, flat surface for printing but also more rigidity than it’s bulkier cousin C-flute. You’ll often see this type of material in retail store displays. We’ve chosen to offer B-flute in our Earlock Mailer, One Piece Folder, Tuck Top Mailer, Full Overlapping Carton, Regular Slotted Carton and Display Header.

C-flute — Heavier

This guy is most commonly used for shippers with a thickness of 3/16″. It’s the most widely used in the world (about 80% of corrugated containers)! The flutes are taller here, giving C-flute somewhat better cushioning properties than B-flute.You are going to be able to pack heavier products with this board due to it’s crushing resistance and stacking strength. C-flute is used with our Regular Slotted Carton, Full Overlapping Carton, and Half Slotted Carton.

As you can see, several of our products come in more than one flute. And to make things just a little more complicated, many also come in different board strengths.

Our team will help you to determine the right type of board strength and type for your corrugated cardboard needs. Talk to us today and tell us about your requirements and we’ll take care of the rest.

How can we help?

We’re all ears. Drop us a line and we’ll get in touch!

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