The lightening of a rug's colors after long exposure to direct sunlight, most noticeable when one part of the rug sat in a sunny window patch while the rest stayed in shade, leaving that area visibly paler. Natural dyes soften with age in any case, but patchy fading counts as a condition flaw and is not the same as abrash, the gentle color variation that comes from dye batches and wool. Curtains or blinds at peak hours, UV-filtering film, a piece of fabric laid over an exposed patch and occasional rotation of the rug limit it; a rug sunned outdoors to dry should not have its face left long in strong sun.