Finding a single foreign fiber in half of the spots wasn’t likely a coincidence, so the key was to:

1. identify the foreign fibers;
2. prove that the fibers were bleeding; and
3. determine where the fibers came from.

Fiber Identification

Under a microscope the fibers had the scaled appearance that is characteristic of hair fibers. (Figure 1.) They dissolved in sodium hypochlorite, so they were definitely hair fibers of some sort.

Hair fibers could have come from any number of sources — cashmere sweaters, wool socks, a scarf. But these were too big to have come from clothing, so the first thing that occurred to me was humans. After all, it was California and they had two teenagers (who had hair), so the first thing I asked was whether anyone in the house had or had ever had pink or purple hair. Seemed like a logical enough question. The homeowner assured me that everyone’s hair color was natural. My first guess appeared to be wrong.

So far we only know what general category of fiber it is — some kind of hair — but not where it came from. That could be impossible to find. It could have been a neighbor’s hair or clothes. But it also could have been an area rug, and they happened to have a very nice woven wool area rug in a tile-floored dining area adjacent to the kitchen.

The rug had a dark burgundy border — so dark that individual fibers appeared black. It shed readily just by brushing a hand over it. Of all the colors in the rug, only the burgundy yarn exhibited such extreme shedding. The released fibers were quite short and generally looked like the ones found in the pink spots. The fibers also had scales and dissolved in sodium hypochlorite.

We’ve got a bleeder!

At this point it looks like the rug is the source of the fibers. But could the bleeding be reproduced?

The dark fibers from the carpet bled readily when placed on filter paper with a drop of ammonia. They bled less with water, even less with acetic acid, and not at all with acetone or mineral spirits. Sample fibers from the rug behaved the exact same way.

Getting Around

Unlike clothing fibers, carpet fibers are too big to stay airborne and drift around the house. They were probably tracked around the home by foot traffic.

The fibers apparently were removed from about half of the spots by vacuuming after cleaning. The remaining fibers were solidly tangled among the carpet fibers and wouldn’t come out with vacuuming.

Fortunately the rug had not been placed directly on the carpet, in which case the bleeding would have been horrendous (though probably easier to figure out).

Cased Closed

It was fortunate that the carpet in one bedroom was not cleaned, because it provided a good view of what the cleaner would have seen (and not seen) before cleaning. The wool fibers were there, but they simply weren’t conspicuous enough to notice on a pre-cleaning inspection.

The homeowner was surprisingly rational about the whole thing. She recognized that it wasn’t the cleaner’s fault. The last I heard was that she was going to look into whether her homeowners insurance would cover replacement, or at least correction.

About 250 square yards of an off-white BCF nylon frieze was installed throughout a large, single-family home in Southern California. The carpet was about one year old and had just been cleaned for the first time.

I was contacted by the cleaner, who cleaned the carpet with a truck-mounted hot water extractor, and whom the homeowner was preparing to sue for damage she felt was caused by his cleaning.

Initially I spoke with the homeowner by telephone, who explained that hundreds of small, bright pink spots appeared the morning after the carpet was cleaned. Both she and the cleaner were sure that the pink spots had not been there before cleaning. The carpet in one of the upstairs bedrooms, which was not cleaned, was not affected.

Inspection revealed exactly what the cleaner and homeowner had described — hundreds of small, pink spots, each about 1/4 to 3/8 inch across. They were irregularly-shaped, not round like a drip, and appeared to be more or less randomly distributed throughout the home. They were not concentrated in traffic paths and they did not occur in any discernible pattern. However, they were absent underneath furniture, such as sofas, that sat down flush on the carpet, despite the fact that the furniture was moved for cleaning.

The home was occupied by two adults and two children in their late teens. There were no pets and, aside from these weird spots, the home was immaculate.

The pink coloration was confined to the upper half of the pile, mostly at or close to the surface. None appeared at the base of the pile. In cleanability tests using an alkaline detergent solution, the pink spots showed some transfer to a white cotton towel. They showed very little transfer with an acidic detergent, and no transfer with any solvents.

By this time things weren’t looking very promising for the cleaner. He acknowledged that the spots weren’t there before he cleaned it, but he said that he had not seen them after cleaning either. Unfortunately, they were everywhere he cleaned and they weren’t found where he didn’t clean.

Now, this cleaner was no amateur — he’s an IICRC-certified Master Cleaner. He happened to be a personal acquaintance, and I knew him well enough to know that he showed meticulous attention to detail and knew what he was doing. He took excellent care of his equipment and kept it in good working condition. As far as he knew, he’d never had mysterious pink spots appear before. But hey, accidents happen, and if this was his fault that’s exactly what I’d tell him.

One more detail: After staring at these spots for a while, I noticed that about half of them had a single thick, black fiber about 3/8 to 1/2 inch long in the center. Like the spots, these black fibers were also located near the surface of the pile and did not extend down to the carpet’s back.

So, with the cleaner on the hook for $7,000 worth of new carpet, what do you do next?

A corollary to Murphy’s Law says that you always find something in the last place you look. (Another says that Murphy was an optimist.) Occasionally the first place you look is the right place and therefore also the last place. This case was like that. It turned out not to be so hard after all.

I snipped off some of the white fibers and took some sample tufts. Back at my world-class carpet lab (read: workbench of random gadgetry), I put a tuft under the microscope and here’s what was there:

Here’s a cross-sectional view:

Some of those fibers aren’t like the others. Rather than being relatively large, deep-red trilobal fibers, the ones that were poking out of the pile were small, round and white, with a black core. In case you don’t recognize those, they’re carbon-core anti-stat fibers, electrically-conductive fibers that are added to yarn to help carpet bleed off static electricity.

It turns out that those fibers weren’t crimped very well, so with just a little friction from foot traffic they straightened out and protruded 1/8 to 1/4 inch beyond the pile surface.

Resolution

The problem was clearly a manufacturing defect originating at the fiber producer, who also processed the yarn.

The fix was easy and permanent. The carpet was pile-lifted to pull all these fibers to their longest possible length, then microsheared to cut them back down even with the pile surface.