A carpet or rug may seem to change color in certain areas. When you look at the carpet from one angle, these areas will appear to be lighter than the rest of the carpet. Viewed from the other side, these spots appear darker. This condition is called shading.
Carpet pile has a natural slope in one direction. As long as the tufts slant in the same direction, the carpet has uniform color throughout. However, some of the tufts may slant against this normal pile lay, causing a variation in the way light is reflected from the napped surface.
Changes in the lay of pile usually develop gradually in traffic areas or in front of frequently used articles of furniture. However, shading may also occur in areas of less traffic and under furniture. It can even be present in brand new carpets! Shading occurs most frequently on dense, deep, velvety, cutpile carpets. Many Chinese and dense-pile Indian rugs will show some pile distortion after use or the first cleaning. Although it can affect multicolored or printed-design carpet, the problem is most obvious on solid colored carpets.
In some cases, shading becomes more apparent after the carpet is cleaned, which may lead you to believe the shaded appearance developed during the cleaning process. But, this phenomenoncannot occur overnight; it must develop gradually over time. The shading was probably not visible before cleaning because of lighting, the placement of furniture or uniform soiling over the entire surface.
Little can be done to prevent or correct shading; it is an inherent characteristic of certain types of carpet. It can be slowed by vacuuming or brushing the pile in one direction during daily or weekly maintenance.