Guide · For the trade
UV resistant rugs and carpet: lightfastness, fading in sun, and what to specify by room
UV resistant rugs are made of solution-dyed fiber, almost always polypropylene or solution-dyed nylon, where the pigment is locked inside the fiber rather than applied to its surface; they hold color through years of direct sun where a piece-dyed wool or a viscose would fade in a season. Lightfastness on a spec sheet is an AATCC 16 xenon-arc result on a 1 to 5 scale, and a grade of 4 or better at 40 hours is the number to look for in a sunny room.
This guide is for the designer specifying a rug or broadloom for a room with real sun: a south-facing great room, a sunroom, a covered terrace, a glass-walled stair. It covers how fading happens, which fibers resist it, how to read lightfastness on a spec, and what to tell the client. Outdoor sizing and construction are in the indoor-outdoor rugs guide; this one is about color holding.
How carpet fades, and why it is not only the sun
Fading is dye breaking down. Ultraviolet light is the main cause, but ozone and the nitrogen oxides from gas appliances do the same thing more slowly, which is why a rug in an interior room can still lose color over a decade. The dye chemistry decides how fast: acid dyes on wool and nylon fade at a moderate rate, disperse dyes on polyester somewhat faster in direct sun, and the pigments in solution-dyed fiber very slowly, because light has to break down the polymer itself to reach them. Natural dyes on hand-made rugs fade fastest, and that softening is part of what a client buys in a vintage-look piece.
Carpet lightfastness: what the number on the spec means
The carpet industry tests lightfastness with AATCC Test Method 16, a xenon-arc lamp that simulates sunlight through glass. The sample is exposed for 40 or 80 hours and the color change is rated on a gray scale from 5 (no change) to 1 (severe). Residential lines are usually tested at 40 hours, contract and hospitality lines at 80. Specify a grade of 4 or better at 40 hours for any room with a window, and grade 4 at 80 hours for a sunroom, a window wall or an atrium.
| Fiber and dye method | Typical lightfastness | Where it holds | Where it does not |
|---|---|---|---|
| Solution-dyed polypropylene | Grade 4 to 5 at 80 hours or more; UV stabilized | Outdoor, sunrooms, window walls | Nowhere on color; it is the least soft underfoot |
| Solution-dyed nylon | Grade 4 to 5 at 80 hours | Sunny family rooms, halls, commercial | Limited palette compared with piece-dyed |
| Piece-dyed nylon or polyester | Grade 3 to 4 at 40 hours | Bedrooms and rooms with filtered light | Direct sun on a dark or saturated color |
| Wool, acid dyed | Grade 3 to 4 at 40 hours | Most living rooms with normal glazing | Deep blues, reds and greens under full south sun |
| Viscose, bamboo silk, silk | Grade 2 to 3 | Bedrooms, interior rooms | Any direct sun; the fiber yellows as the dye fades |
The grades are typical ranges, not a guarantee for a particular style. Ask us for the mill's test result on the style you are specifying; most contract lines publish it on the spec sheet and the residential mills have it on request.
Does wool fade?
Yes, and the client should hear that before the rug goes under the window. Wool holds dye well and fades gracefully, evenly and toward a softer version of the same color, which is why a 60-year-old wool rug still looks right. Undyed wool fades least; deep saturated colors fade most. With normal double glazing and no direct sun on the floor, a wool rug keeps its color for the life of the pile. In a south- or west-facing room with the sun on the floor for hours a day, expect a visible difference between the exposed and the covered areas within 2 to 3 years unless the window has a UV-blocking film or low-e glass.
Carpet fading in sun: the rooms where it decides the spec
For a sunroom, a glass-walled stair, a covered patio or any room where the sun lands on the floor for more than an hour a day, specify solution-dyed fiber and stop worrying. Couristan's outdoor collection is almost entirely UV-stabilized polypropylene and reads as a flatweave or a wool-look machine-woven piece; Stanton and Bloomsburg each run outdoor and performance lines on UV-stabilized polypropylene and polyester, and Masland's solution-dyed nylon broadloom carries a 20-year fade-resistance warranty on many styles. Our indoor-outdoor broadloom lists about 200 of them and the outdoor rug filter nearly 400. For a living room with ordinary light, wool is fine and a mid-tone or heathered color hides fading that a flat dark solid would show. For a bedroom, anything goes, including viscose, provided the sun does not fall on the floor.
What to tell the client about keeping color
Rotate any rug 180 degrees twice a year so the window side and the room side age together. Specify a UV-blocking window film or low-e glazing for the rooms that matter; a good film cuts UV transmission by more than 95 percent and does more for the rug than any fiber choice. Close the blinds in the hours the sun is on the floor. For broadloom, keep attic stock from the same dye lot, because a repair cut from a new lot will not match the faded original; the dye lot guide covers that.
Fading, crocking and bleeding are three different things
A client who says the rug "lost color" may mean one of three faults. Fading is light breaking down the dye in place. Crocking is dye rubbing off onto a sock or a white sofa skirt. Bleeding is dye moving in water after a spill or a cleaning. A rug can be excellent on one and poor on another, and each has its own test; the colorfastness guide covers the second two.
Questions designers ask
Which rugs are the most UV resistant?
Solution-dyed polypropylene rugs, followed by solution-dyed nylon. The color is pigment inside the fiber, UV stabilized during extrusion, so there is no surface dye for light to break down. They are the rugs to specify outdoors or in a glass room, and they come in flatweave, machine-woven and hand-loomed constructions that read as wool at a distance.
Does wool fade in the sun?
Yes, evenly and slowly. In ordinary light a wool rug keeps its color for decades; under direct sun on the floor for hours a day, deep colors soften visibly in 2 to 3 years. Rotation, window film and a mid-tone color are the three controls.
How do I read lightfastness on a carpet spec sheet?
Look for AATCC 16 followed by an hours figure and a grade. "AATCC 16, 40 hours, grade 4" means the sample showed only slight change after 40 hours of xenon-arc exposure, which is adequate for any residential room with a window. Contract lines are tested at 80 hours and should still show grade 4. A grade of 3 belongs away from the sun.
Can a faded carpet or rug be fixed?
Wool and nylon can be re-dyed on site to bring a faded band back toward the covered color, with a close but not perfect result. Polyester, polypropylene and viscose cannot. For a rug, rotation before the fade is the only real fix.
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