Microshearing

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.

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