A microshear is one of the most versatile corrective tool available. It can be used to correct a wide variety of problems and restore many defective carpets to first quality condition. This bulletin discusses the most common problems for which shearing is used.

What is Microshearing?

A microshear (figure 1) is an electric carpet shear with a helical blade, usually three, four, six or 12 inches wide. (Figure 2.) This type of blade is identical to that with which carpet is sheared at the mill, resulting in a finish that matches — and often surpasses — the carpet’s original appearance. (Figure 3.)

Because of its size, a microshear usually can only shear to within about four to six inches of walls and edges; carpet in perimeter areas is sheared with a hand-held shear, such as a carver or “sheep shear” with an oscillating blade specifically designed for shearing carpet.

Fuzzing and Pilling

Fuzzing is a condition in which fibers that are still attached to the carpet protrude above the pile surface. (Figures 3, 5.) Pilling is an advanced stage of fuzzing in which protruding fibers become entangled into small balls on the surface of the pile. (Figure 4.) Since the fibers are still attached to the carpet, fuzzing and pilling are not removed by vacuuming.

Fuzzing usually is caused by one or more of the following three factors:

• Inadequate alignment of fibers during the processing of staple yarns. This is the most common cause of fuzzing, and fuzzing of this type usually is very correctable.

• Incomplete encapsulation of the pile fibers by the carpet’s backcoating material, resulting in slippage when the carpet is subjected to traffic and maintenance. This condition occurs in both staple and continuous filament yarns. Virtually all fuzzing in continuous filament (BCF) yarns is caused by incomplete encapsulation. This condition usually is not permanently correctable because the cause of the problem cannot be corrected.

• Product design: Use of staple yarns in loop-pile constructions often leads to fuzzing, especially in carpet with large, felted wool yarns, wool blends, and synthetic staple. This condition usually is correctable by a combination of pile lifting and shearing.

Even in cut–pile constructions, most staple yarns exhibit a degree of fuzzing, and this is considered normal. However, the point at which fuzzing becomes “unacceptable” is largely left to the judgment of the end user.

Correcting Fuzzing

In terms of correction, fuzzing typically yields excellent results. If incomplete encapsulation is the cause, the fuzzing is likely to reappear. However, the majority of fuzzing is caused by poor yarn processing and product design, and those types of fuzzing usually are eliminated successfully by aggressive pile-lifting followed by microshearing. In most cases, the quality of the pile finish after this correction is actually better than new, often similar to that of continuous-filament products.

Can Loop Pile Carpets Be Sheared?

Usually yes, but they must be sheared much more carefully than cut–pile carpets. (Figure 5.) It is often preferable to use oscillating clippers, skimming the blades over the surface of the pile. Clippers are better at following uneven pile surfaces and irregular floors in direct–glue installations. Fuzzing in continuous-filament loop-pile styles usually is usually caused by fiber slippage, and usually cannot be permanently corrected.

Shedding

Shedding is the complete release of loose fiber from the carpet’s pile. Moderate shedding usually is not considered a defect, but corrective action may be necessary if the claimant is persistent or if the duration or volume of shedding is extreme. (Figure 6.) Like fuzzing, shedding may be caused (at least in part) by poor yarn encapsulation, but in most cases the released fibers are simply short staple fragments that did not extend far enough into the carpet’s back to be secured.

A degree of shedding can be expected throughout the life of a carpet with staple pile yarns, but it is greatest when the carpet is new. The rate at which it diminishes is determined by the frequency and effectiveness of vacuuming, the weight and thickness of the pile, and the length of the staple fibers used to make the yarn.

When circumstances of a complaint make correction necessary, the procedures used are identical to those for correcting fuzzing and pilling: aggressive pile lifting followed by microshearing. The pile lifter pulls the majority of the unsecured staple fibers out of the carpet, and in doing so usually causes considerable fuzzing, which is then eliminated by shearing.

Side Match Correction

In tip-sheared, cut-and-loop, overtufted and some cut-pile graphic styles, differences in texture at seams often are caused by variations in tufting and/or shearing from one side (or one end) of the roll to the other. (Figure 7.) These differences often can be corrected by carefully shearing one edge to match the other more closely. (Figure 8.)

Graphic Streaks

In cut-pile and cut-and-loop graphic styles, variations in the dominance of different colors in the carpet’s pattern can create continuous or intermittent lengthwise streaks. (Figure 9.) In many cases, careful shearing can reduce or eliminate these defects and restore the carpet to first-quality condition.

Tufting & Weaving Defects

In cut-pile styles, imperfections such as high stitch rows (figure 10) and J-cuts, minor texture imperfections, and a variety of other defects can be dramatically improved or eliminated by shearing. Even low stitch rows can sometimes be removed by shearing if they are not too far below the surface of the pile.

Shearing Defects

In cut-pile carpet, defects such as shear bands and poor finish can usually be corrected by shearing.

Dark, gray or brown lines under doors, around walls, underneath draperies and along the edges of stairs are symptoms of an aggravating problem called filtration soiling. This article explains the cause of this problem and suggests effective methods of prevention and correction.

What is Filtration Soiling?

Filtration soiling is the accumulation of airborne soil—dust, smog, tobacco smoke and other pollutants—where airflow is concentrated and directed over or through a carpet’s pile. The carpet “filters” out these pollutants and gradually becomes soiled and dark.

In addition to the areas shown in the accompanying photographs, filtration soiling can occur anywhere air flows over or through the pile, including places where the carpet’s back has been punctured or torn by installation tools, along seams that abut baseboards, around railings on stairs, and other areas. You may even find it around the holes created in carpet’s backings by the pins of tackless strip. In these cases, the path taken by the air differs, but the cause of the problem is the same.

Filtration soiling may appear over a period of only weeks, or it may take months or even years to become visible. The severity of the soiling will be proportional to the volume of airflow and the relative dirtiness of the air. Its color will vary according to the type of contaminants present. Auto emissions are gray to black; tobacco smoke is tan to brown (and easier to remove by cleaning). It is most visible on carpet of lighter colors, such as off-whites, light grays, beiges and pastels.

Is the Carpet Defective?

No. Filtration soiling is not the result of any defect in the carpet or its components, nor is it an indication of low quality. It can appear on any carpet regardless of price, style, color, construction or face fiber. Since it is caused by airborne pollutants being deposited on the carpet after it is installed, filtration soil is not affected by anything done when a carpet or its pile fibers are manufactured. While fluorochemical soil retardants (e.g., Scotchgard, Teflon, etc.) may make it somewhat easier to remove, no fiber modification or protective finish can prevent filtration soiling from occurring.

What Causes the Airflow?

In most cases, the airflow is created by heating and air conditioning systems, thermal expansion and contraction of air, or natural convection currents in the structure. It also may be caused by wind blowing through windows that regularly remain open.

Can it Be Prevented?

Leaving inside doors open as much as possible will help prevent filtration soil from accumulating in doorways. In other areas the airflow itself must be stopped. Along walls and staircases, the carpet will need to be disengaged and the gaps through which air flows must be completely sealed off. (Silicone caulking and polyurethane foam insulation are ideal for this purpose.) However, if any gaps remain, air will find them. Sealing off some gaps may simply force air to find another route—possibly through the carpet in another area.

Can It Be Corrected?

Usually filtration soil is at least partially correctable by a professional cleaner; however, it rarely responds completely to routine cleaning. Filtration soil consists primarily of extremely fine particles—much smaller than soil from other sources—which can be very difficult to remove. It is thought that because of their small size, the particles are held stubbornly to the fibers’ surface by van der Waals’ forces (not static electricity, as is sometimes claimed; think gecko feet, not TV screens). Some components of filtration soil—auto emissions, for example—are oily in nature and have an affinity for synthetic carpet fibers. These factors, combined with the fact that the soil typically remains on the fibers for months or years, make filtration soil highly resistant to ordinary cleaning. Natural fibers like wool cannot tolerate the chemically aggressive cleaning techniques usually required to remove filtration soil.

The largest case (by dollar value) I ever worked on was a lawsuit against a construction company, who was blamed for severe airflow problems, which caused extreme filtration soiling. As (bad) luck would have it, nearly all of the units had white or beige carpet with nylon or polyester pile. By conducting extensive cleanability testing, I came up with a four-step procedure which successfully removed 90-100% of even the most severely affected areas:

Repeat these steps until it stops responding or, more likely, it’s all gone. Note that these agents may damage paint and wood finishes, and some weakening of the carpet’s lamination may occur, at least while the carpet is wet. (That’s nothing a little latex won’t fix.)

If you’re going to the trouble of disengaging the carpet to seal off areas where air flows, you might not have to worry about cleaning at all. You can take advantage of the reinstallation to restretch the carpet (using a power stretcher, of course) and physically trim off the soiled edges. If the airflow is completely stopped, then the problem is permanently solved.