Corrugated paper is categorized by its flute. The flute is the structure of the waves in the paper, which is typically sandwiched between two non-fluted paper to form cardboard. The types of corrugated paper are named according to flute profile--marked from A to C and E and F. The larger the flutes, the more strength and cushioning they provide. Corrugated paper with smaller flutes folds easier and has better printability. Different flutes can be combined to form one cardboard sheet.
The A flute profile has the largest flutes with 36 flutes per linear foot with each flute at 1/4-inch wide. A-flute corrugated paper is the thickest and has the best cushioning and stacking properties. It also offers excellent stiffness and crush resistance. These properties make it ideal for protecting fragile items.
B-flute corrugated paper is 1/8-inch wide and is the second largest. It has a lower arch than the A-flute, and thus able to fit 49 flutes per linear foot. This also provides a stiff, flat surface for printing and die cutting. It has good puncture resistance and is normally used by packagers as pads, partitions and other forms of inner packing.
The C flute corrugated paper splits the difference between A and B flutes. The C flutes are 11/64-inch wide, with 41 flutes per linear foot. It is the most widely used flute type, with approximately 80 percent of corrugated containers made out of this type. C-flute corrugated paper offers good crush resistance and good stacking strength.
The E flute has the most flutes per linear foot with 94 flutes at 1/16-inch wide. The number of flutes gives this corrugated paper the greatest crush resistance and best surface for printing. The thin profile of this board helps reduce box size and thus, storage space. The E-flute corrugated paper is typically used for cosmetic boxes and boxes for fragile items like glass and ceramic. It is also used for pizza boxes.
The F flute corrugated paper has flutes that are almost half the thickness (1/32 of an inch) of an E flute, fitting 128 flutes per linear foot. The dimensions of the F flute means that converters and packagers can reduce the amount of fiber in packaging whilst making a more rigid box. It is normally used for specialty packaging, point-of-purchase displays, jewellery, cosmetics and shoe boxes. McDonald’s uses this type of corrugated paper to box its Big Macs.