Permanent Pile Reversal Shading is a phenomenon that can appear in any cut pile carpet. Its occurrence is random and its causes are largely unexplained. It is also commonly referred to as watermarking, pooling or puddling. A cut pile carpet that has ‘shaded' will show areas lighter or darker than the surrounding carpet pile. This variation is caused by the reflection of light from pile tufts which come to lay in different directions.
Visually, Permanent Pile Reversal Shading is not unlike the brushed appearance of other cut pile fabrics such as suede, velour and velvet, although the appearance change in a carpet that has ‘shaded' will be permanent.
As Permanent Pile Reversal Shading will have some impact on the appearance of a carpet, consumers should consider the possibility that it may occur when buying a cut pile carpet.
SHADING - common usage terms and common misunderstandings
The general term ‘shading' is sometimes incorrectly used to describe a number of carpet characteristics that are not related to Permanent Pile Reversal Shading. The following outlines common usage terms and explains which terms are, and which terms are not, Permanent Pile Reversal Shading.
Watermarking, pooling and puddling are terms used to describe irregular areas of light or dark in the carpet that may resemble water spillage marks. These effects are permanent and referred to as Permanent Pile Reversal Shading. The appearance change is permanent - it will not go.
Footmarking is seen as small localised marks on the carpet pile that are typically caused by dragging or scuffing associated with normal foot traffic. The appearance change caused by footmarking is temporary and can be reversed by vacuuming or brushing of the pile fibres in the normal direction of pile lay. Footmarking is a characteristic of most cut pile carpets and is not related to Permanent Pile Reversal Shading.
Tracking describes the flattening or crushing of the carpet pile in areas that receive more concentrated foot traffic than adjacent areas. Tracking can appear in carpets of any construction and will depend on traffic patterns and the wear characteristics of the particular carpet that has been installed. Tracking is not related to Permanent Pile Reversal Shading.
What is known about Permanent Pile Reversal Shading?
Despite extensive research and development of methods and techniques to minimize the occurrence of shading, the characteristic is not predictable. However, the consensus of expert opinion about Permanent Pile Reversal Shading is that:
It can occur in any cut pile carpet (or rug) including hand knotted, tufted, woven, bonded, knitted or hand-made carpets and rugs.
It can occur in carpets made from all carpet fibres and blends of different fibres (e.g. nylon, wool, acrylic, polyester, polypropylene and their blends).
Its occurrence will not lead to premature wear of the carpet and it will have no effect on the durability of the carpet.
Where does Permanent Pile Reversal Shading Occur?
Although research from around the world is inconclusive, location factors are thought to be linked to the incidence of Permanent Pile Reversal Shading. Trials have shown that an installed carpet, showing no sign of Permanent Pile Reversal Shading, can develop the phenomenon when re-laid in a shading prone location. However, it has not been possible to isolate the specific factors responsible although floor temperature, humidity, air currents, static electricity and earth rays have all been investigated as possible causes.