A hair cut is a smooth, sharp cut in the paper that is too uniform to be a tear. It is caused by foreign materials inside the pulp during the paper making process. Such foreign materials could be a hair or other synthetic materials such as from brushes.
The actual cut does not take place until the paper reaches the super calendering part of the paper making process. Super calendering is when the paper passes one of it's final stages and is compressed between metal rollers to get it's thickness and establish it's basis weight.
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| Super calendering rollers. This involves multiple passes through rollers to get compressed to the proper thickness. |
When the paper is compressed to it's point of final thickness, any hairs or similar foreign objects will form a "cut" in the paper. This looks like a long, smooth line that is sharply defined.
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| Hair cut. |
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| A hair cut paper defect has a smooth and defined path. |
There is no definite direction or length to a hair cut.
They are a rare defect, but when they do happen will cause a paper jam or web break in the offset printing process. They are the fault of a paper manufacturer and evidence such as the picture shows should be found to make a claim.
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