Shrinkage

FABRIC FACTS

Shrinkage continues to be a serious problem for drycleaners and consumers alike. Any shrinkage over 2% will alter the fit of most garments and will be especially noticeable to consumers with tight and formfitting garments. Shrinkage of 5% in trousers with a 35" waist and a 32" length will reduce the size over 1 1/2".

TYPES OF SHRINKAGE

(1)Relaxation (or fabric) shrinkage. Relaxation shrinkage occurs during the initial drycleaning of a garment. This type of shrinkage takes place because the woven or knitted goods are stretched during manufacture. These fabrics have a high potential shrinkage capability. (2) Progressive (or fiber) shrinkage. Progressive shrinkage occurs during subsequent cleanings. A consumer may not notice this type of shrinkage until the garment has been cleaned several times. (3) Felting shrinkage. Felting is extreme shrinkage of wool and other animal fibers when exposed to heat, moisture and mechanical action. The scales of the fibers interlock and the fabric becomes thicker and smaller. Shrinkage occurs in fabrics or yarns due to (a) A lack of or improper pre-shrinkage treatment during manufacture, (b) An improper heat stabilization treatment during manufacture, and (c) The improper choice or application of resins, sizing agents and coatings.

SHRINKAGE CONTROL

To be considered serviceable, a consumer's garment should not shrink more than 2%. Manufacturers use the following processes to control shrinkage (a) Compressive shrinkage controls are used on fabrics of cotton, linen and some rayon. A fabric is used to compress or shrink another fabric by heated rollers. Sanforization and Rigmen are trade names for compressive shrinkage processes used on woven cloth. (b) Heat setting or stabilization is used on thermoplastic fabrics. The dimensional stability is maintained by subjecting the fabric or yarn to a predetermined degree of heat, moisture and pressure. (c) A resin or other coating is applied to a fabric yarn or fiber to stabilize it. Rayon fabrics are frequently impregnated with sizing agents. Surface coatings are sometimes used to mask the scales of the wool fiber and reduce its potential to shrink and felt.

FACTORS THAT PRODUCE SHRINKAGE

Heat, moisture and mechanical action are the three factors that produce shrinkage. Depending upon the fiber, one or more of the factors become dominantly critical. For instance, thermoplastic fibers are more sensitive to heat; natural fibers and rayon are more sensitive to moisture.

IDENTIFICATION

There is no practical way to determine in advance whether a fabric will shrink. Angoras and soft woolens always have high shrinkage potential, since the yarns are most often not pre-shrunk. Wool gabardines, crepe and matte jersey are potential shrinkage problems.

DRYCLEANING

Careful classification and control of heat, moisture and mechanical action will reduce the hazards of shrinkage. 
(1) Angora and angora blends should be processed in a moisture-free load, with a high solvent level, for 2-3 minutes, with minimum mechanical action. Solvent temperature should not exceed 80°F. Hot solvent increases the possibility of “free moisture” and shrinkage. Angora should be reclaimed at the minimum temperatures required by the type of solvent used. 
(2) Soft woolens, rayon and crepe should be run in a moisture free load for 3-5 minutes. Solvent temperature should not exceed 80°F. Loose knits should be placed in a net bag to reduce mechanical action. Soft woolens should be reclaimed at the minimum temperatures required by the type of solvent used. (3)Thermoplastic fabrics (acrylic, polyester, nylon) are run according to fabric or knit construction. 3-5 minutes for fragile or soft knits, 7-8 minutes for more durable construction. Solvent temperature should not exceed 80° F. Reclaim at the minimum temperatures required by the type of solvent used. Eliminate moisture in the load to reduce shrinkage.

SPOTTING


When garments are spotted, they should be completely dry before entering the drycleaning machine. The moisture content of only one garment being cleaned wet can increase the relative humidity of the solvent, causing an entire load of garments to be affected.

WETCLEANING


If the trimmings and accessories show if they can be safely processed in water when tested, wetcleaning may be an option. Wetcleaning will not adversely affect polyester, nylon, acrylic and other thermoplastic fibers. Care labels or hangtags may suggest washing as preferable.

FINISHING


Where shrinkage is a possibility, limit the use of steam and moisture. Don't over-steam the fabric on the pressing machine or steam air finisher.

SUMMARY


Shrinkage may occur in any type of fabric. Shrinkage will occur because of (1) A lack of a suitable pre-shrinkage treatment, (2) Faulty heat setting (3) Defective sizing agents. There is no practical way to test a fabric before drycleaning. When drycleaning a garment that may shrink, shrinkage may be avoided by proper load classification and limiting the use of moisture, heat and mechanical action.

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