Shift marks are one of the most controversial claims in the carpet industry. Carpet manufacturers will tell you that shift marks are a normal characteristic and not a defect. Others in the industry often disagree. So what are shift marks and are they a defect or not?
What are Shift Marks?
Shift marks are more commonly seen as narrow lines or bands that repeat across the width of the carpet at regular intervals. The surface of the carpet may have narrow widthwise gaps in the pile. The actual gaps can sometimes be difficult to see. Shift marks are most common with graphics or stepover stitch loop-pile carpet. Shift marks can also occur with cut pile carpet.
Shift marks are created
Tufted carpet is manufactured using a tufting machine with a needle bar that can hold up to 1,800 or more needles. A tufting machine that has been set to manufacturer 12 foot wide 1/10 gauge carpet holds 1,440 needles across its width.With step-over stitch the needle bar shifts in a side-to-side direction. The needles stitch the yarn through the primary backing material. As the needle bar is shifting, tension is placed on the yarn as it is being pulled down.
Shift marks are caused by the yarn being starved or pulled down as the needle bar is shifting back and forth.
This added tension results in the appearance of bands or short, little row lines that appear on the face of the carpet. These bands are the most noticeable where they line up at a seam and often start appearing more after the carpet has been down for a while. Shift marks are not correctable.
Are Shift Marks a Manufacturing Defect
No: With commercial looped carpet that is manufactured using a shifting needlebar, it is a sometimes an unwanted characteristic that is not correctable.
Yes/Maybe: With residential cut pile carpet. If the shift marks are not seen in a large sample of the carpet that the consumer ordered from, they did not receive the appearance they bargained for. This is a visual defect though the manufacturer may see it otherwise. It does become the dealer/installer responsibility not to install carpet with visual defects. While shift marks do affect the appearance of a carpet they do not affect its performance.