ThinkDon is our periodic Question and answer forum with expertise in the world of large format package printing by our VP of Manufacturing, Don Ellis.

ThinkDon - From Huston Patterson Printers

ThinkDon is our periodic Question and answer forum with expertise in the world of large format package printing by our VP of Manufacturing, Don Ellis.

What's grain direction got to do with it?

Grain direction has very important implications for your print job. If it is incorrect, the various components of the corrugated package or display may be incompatible.


There is a wide variety of material manufactured with wood pulp, including sheets for litho lamination, top sheets and corrugation.

The most important rule concerning grain direction, and arguably the only consideration, is for all of the pieces (litho label or top sheet and corrugation) to have the same grain direction. When moisture (adhesive) is applied, the fibers in the stock and corrugation will expand. The fibers must expand in the same direction.

Think of a fiber as a piece of string. If moisture is applied to the string it will swell and become bigger around before the length of the string will change. Therefore, if the grains are not running the same direction, the different pieces will expand and contract in different directions. It is this difference that may cause tunneling, bubbling and excessive curl.

To check the grain direction of a printed or unprinted c1s litho label or top sheet, cut a small section from the corner of the sheet, paying close attention to the orientation of the sample to the sheet. Then, wet the back or uncoated side of the sample. The sample will curl indicating the long direction of the sheet. This is an excellent example of the fibers swelling more around the fiber than the length. The grain direction of corrugation is established by checking the orientation of the flutes. The grain direction is always 90 degrees to the flutes.

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