Widthwise Lines in Carpet: Shift Marks

photo of carpet shift marks | Glenn Revere

Beautiful carpeting is made on very complicated machinery. When more parts make up a machine, more things can go wrong with the manufacturing process. The carpet mills know this. They have extensive inspection and quality control departments whose function is to find defective carpet and keep it from arriving at your home. In spite of these controls, mistakes happen.

Carpeting can contain various types of streaks, either lengthwise or widthwise in direction. There are many causes for these streaks. I recently looked at some carpet that had widthwise lines/streaks throughout the installation. The complaint for this newly installed carpet was listed as “uneven dye.” It was not noticed until the day after installation. I was asked by the mill to determine the cause of this problem. I arrived at my conclusion by using a process of elimination.

The lines, approximately 2” apart, were visible as soon as I walked into the home. The carpet was installed in a downstairs combination kitchen/nook/family room and the upstairs office of a well-maintained suburban home.

While it was obvious to me that the streaks ran across the carpet, I used a “pencil test” to determine the direction of the pile. This then determines the lengthwise and widthwise direction of the carpet itself. For a pencil test, one places a piece of paper on the carpet. One then rubs a pencil on the paper. The paper moves in the direction of the pile. The test showed that the streaks ran widthwise. Knowing this eliminates several possible conditions that can only appear as lengthwise streaks or lines.

The carpet had a bumpy, corrugated appearance. However, when I ran my hand over the carpet pile, it felt smooth. I used a lighted 5 power magnifier to closely examine individual tufts (carpet yarns). I checked to make sure that yarn size, the ply and twist count, pile texture and pile height were consistent across the streaks.

I vacuumed the carpet. It looked the same. I hand steamed the pile. This process removes any wrinkles and lifts severely crushed pile. The carpet looked the same.

I could only conclude that the lines are machine shift marks. The carpet industry has developed a reference guide for inspectors that standardizes everything from performing inspections to types of complaints. The guide is called the ANSI/IICRC S800 Standard and Reference Guide for Professional Inspection of Textile Floor Coverings. One section includes “Types of Complaints: Manufacturing Defects.” A subsection lists various types of widthwise lines/streaks and states:

“machine shift marks… appear in graphics or step-over tufting as narrow lines repeating across the carpet at regular intervals. The surface of the carpet may even have widthwise gaps in the pile.”

This rare condition will not affect the performance of a carpet. It is aesthetic only. However, the homeowners were very upset with the appearance of their new carpet and insisted on a replacement. Hopefully, the replacement carpet will be streak-free.

Who is Glenn Revere?

Glenn Revere has been a carpet expert since 1973. He’s a certified flooring inspector and the author of All About Carpets, the only book written to protect and inform you about your carpet choices, from carpet buying and carpet warranties to carpet care and maintenance. You can find him on Facebook, Google+ and Twitter.


Photo: Glenn Revere

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