Types of Corrugated Materials Available

Single Face Sheet
A corrugated medium with a linerboard facing adhered to one side. It can be manufactured in sheets or rolls. Single face is principally used as a wrapping material, and occasionally for interior packing or padding.

Single Wall Corrugated
A corrugated medium with a linerboard facing adhered to both sides. It is also referred to as "Double Face". This popular and versatile 3-ply construction is converted into a wide variety of containers and packaging components.

  • most popular
  • wide range of strengths

Double Wall Corrugated
Two corrugated mediums with a linerboard facing adhered between them and to both sides. This 5-ply construction is most applicable for packing heavy items where high rigidity and protection is required.

  • made up of B and C Flutes
  • extra padding and strength
  • great for stacking heavy items

Triple Wall Corrugated
Three corrugated mediums and four linerboard facings. This 7-ply construction is used where large container sizes are involved, such as pallet packs.

  • oftentimes made up of two layers of C Flute and one layer of B Flute
  • very strong and provides more cushion
  • excellent for storage and transit

Types of Flutes Available

The "Flute" describes the structure of the wave-shaped cardboard material that makes up a board's corrugation.

B-Flute
B-Flute has a low arch height at 1/8” and consists of forty-nine flutes per foot. This means that the medium contacts and supports the liners at a great number of points, providing a stiff, flat surface for high quality printing and die cutting and with excellent crush resistant properties. B-Flute is also preferred for high speed, automatic packing lines and for pads, dividers, partitions and other forms of inner packing. Complex die cuts and beverage trays are excellent applications for B-Flute.  It is also often used for can cases, wrap-around blanks and glass-to-glass packs.

C-Flute
C-Flute came along to split the difference between A (35 flutes) and B Flutes. With 42 flutes per foot, it's thinner than A-flute, thicker than B, and offers good cushioning, stacking and printing properties. C-Flute is by far the most widely used flute size. An estimated 80% of today's corrugated containers are made of C-Flute board. It is often used for glasses, furniture and dairy among others

E-Flute
E-Flute has the greatest number of flutes per foot at 95.  It gives the greatest crush resistance and the flattest surface for high quality printing applications. The thin board profile of E-Flute (it is one-fourth the thickness of C-Flute) reduces box size and saves storage space. Because of its thin profile and excellent cushioning properties, E-Flute can often substitute for conventional folding cartons or solid fiber containers. Examples of E-Flute applications include boxes for cosmetics, fragile glass and ceramic items and delicate instruments. Another growing end-use is for pizza boxes where the retailer wants a cost effective container with good graphics and excellent product protection.

Quality Testing Standards

  • Bursting Test

Bursting test is also known as Mullen Test.  This packaging standard dates back to the early 1900's and became the carrier regulations for corrugated boxes.  Rules were set for certain minimum grades of fiberboard to carry specified maximum weights and sizes. Both the box industry and the shipping industry standardized around these minimum grades.

This type of test basically measures the puncture strength of the material. 

  • Edge Crush Test (ECT)

Early in 1991, the carrier rules were amended by offering an alternative to the existing Mullen Test grades for shippers. That alternative is known as "ECT", wherein the material is measured for its edgewise compressive strength by Edge Crush Test.

ECT is the edgewise compressive strength, parallel to the flutes of a short column of corrugated fiberboard.  In other words, it is the amount of pressure a board/box can withstand before the edges collapse.  Test results are reported as the "pound-force" per inch required to cause compressive failure. ECT correlates directly to Box Compression Test (BCT).

Bursting Test versus Edge Crush Test

Bursting test basically checks the puncture strength of the box/board whereas the ECT yields the stacking strength of a certain material.  Given the size of the box and weight of the item/s, we can compute for the desired ECT of a certain corrugated packaging material. 

The logic behind it is simple.  It may help when the packaging is more resistant to puncture but what we really need is that it will be able to stack upright and not collapse when it reaches its destination.