Cut pile carpets (including plush/shaggy pile carpets) can have a stunning appearance, however some tend to develop pile reversal (also known as tracking, shading, pooling or watermarking). Pile reversal changes the appearance of some areas of a carpet and is best described as if water has been spilt on the carpet/pooling of water on the carpet.
In instances of pile reversal, areas of the carpet appear to become lighter or darker than the surrounding area, depending on the angles from which they are viewed. What is happening to cause this is a change to the direction in which the pile naturally sits. The appearance of shading then occurs because light catches differently on the greater surface area of carpet to the side of the bending fibres facing a different direction. The cause of this phenomenon are not understood and cannot be predicted or prevented.
Pile reversal does not affect the wear or durability of the carpet and is beyond the control of the manufacturer or installer and is therefore not considered a defect or manufacturing fault, but an inherent fibre characteristic. This is corroborated by The Carpet and Rug Institute, and further reading on this topic can be found in their manual titled ‘Pile Reversal (Shading, Water Marking)’.
Although this phenomenon is relatively rare, it is important to be aware of the potential risk of this occurring on your installation. If you wish to reduce your exposure of having this happen in your home, consider loop pile or textured/patterned carpet styles.