This was a very different, unique and interesting problem that was called in by a dealer the other day. He had a consumer whose carpet developed a dark line only at the seam. The dark line extended on either side of the carpet from where it was joined together to the edge of the seaming tape beneath it. This off white carpet had been installed for about 31/2 years and the dark area at the seam had been noticed about one year after installation. The condition, the consumer says, has gotten progressively worse. This is living room in the home with a fairly high quality carpet installed. The dealer explained that the dark discoloration was all the way to the backing of the carpet and nothing like this existed anywhere else in the room. The perimeter areas of the carpet were not discolored or darkened nor was any other area. We could rule out air filtration soiling from this complaint for two reasons, first, no other area or location on the carpet was afflicted with this condition. Second, it would be near impossible for air to filter up through the seam or down into it with the seam tape blocking its path. The seam tape is an impermeable material and it effectively prevents the passage of air, therefore air filtration soiling can be ruled out. The dark line was isolated to the seam only so whatever caused it had to emanate from that area. The dealer also said that this dark line would not respond to cleaning.

Our first thought, after getting all the facts, was that the seam tape or the iron caused the problem. Something must have “burned off” either one to cause the problem but the question was, what was it and why did it happen. After having researched the problem and discussing it with our associate adhesives expert we learned that lower quality seam tapes are often made with extenders to make the thermoplastic go further, just like putting more filler in the latex in the carpet backing. This extender used in the thermoplastic on the seaming tape is a wax which is basically a cheap oil. When the tape is heated the wax is melted with the thermoplastic and the oil in it is burned off as a vapor. This light, volatized oil is carried into the carpet with moisture generated by the heat from the seaming iron melting the thermoplastic on the tape while making the seam. This oil is deposited on the carpet yarn and will actually impregnate the fiber. It leaves a very light residue so it won’t be noticed at the time it invades the carpet fiber. Over a period of time with use, normal air flow through the carpet fiber surface and vacuuming, the yarn affected by the light oil residue will attract soil. The dark appearance on the carpet will manifest itself just like air filtration soiling at the perimeter edges of the carpet but it is a completely different problem from a totally different source.

Because the oil impregnates the carpet fiber it will not come out, so no amount of cleaning will remove this obvious and unsightly dark line. Cleaning may lighten it somewhat but it won’t take it out completely; the dark line will still be visible. How then would you correct this problem?

There would be two ways to correct the problem of the dark line at the seam. The first would be to cut the affected area out. This means removing a four inch section, the length of the seam, from the carpet. No matter how loose the carpet might be, it would be very difficult to stretch it four inches (two inches from either side) to bring the two new edges together. What could be done, if possible and depending on the configuration of the room, how much scrap carpet was left and if it was in big enough pieces, would be this. Loosen up one section of the carpet, move that one section of carpet towards the other full piece to make a new seam, use the scrap to put a fill piece at the wall. If there are any cut outs in the carpet this may be difficult if not impossible to do. You’d have to miraculously have enough carpet left over from the original installation, and everything else would have to be in your favor on this job to do this. The only other alternative is to replace the entire living room carpet. Putting a fill piece in the seam, after 3 ½ years, would be totally unacceptable to a consumer because it would make two seams and be another obvious blemish in the carpet. This “Dutchman” or “Saddle Seam” would be off shade, vary in texture and have an offensive contrasting appearance.

Whose fault is this? It is certainly not a manufacturing defect because nothing in the carpet caused the problem. It is an installation problem caused by the installer using a low quality tape however, the seam tape manufacturer actually caused the problem when they used a cheap, oil based, wax extender and they rightfully should be responsible for repair or replacement of the carpet. The installer wouldn’t even know the tape he used caused the problem and certainly not at the time of installation. After 3 ½ years he may be gone or, at least, hard to convince he had anything to do with the dark line. Ultimately though this problem would fall back on the dealer. He sold the carpet, he hired the installer, he didn’t set guidelines for the installer relative to the quality of his installation materials and he may not have paid the installer enough to buy better quality materials to install the carpet he sold to his customer.

This was a rare and wild problem that few will ever run into. It may have just been a fluke that the installer got a bad batch of seaming tape too. This just goes to show you that just about anything associated with the products in the floor covering industry can cause a problem.