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The Promise of Polyester
Criteria for You to Consider When Selecting Personal Protective Apparel
by Dennis Adams
The terms “fluid-resistant” and “tapered sleeves with fitted cuffs” sound more like features on a durable power suit that maintains the corporate look, flight after flight and meeting after meeting.
But styles can make a good lab coat function better. Along with designs, fabrics and accessories are ushering in better contamination control in a host of life-science environments. Whether for food and pharmaceutical research testing or plant/production applications, the roles of lab coats have many similarities.
Reusable lab coats for laboratories are prime examples: These garments minimize contamination and improve employee safety on many levels. ASTM International (West Conshohocken, Pa.) guided the development of such garments, and understanding these recommended practices is essential when choosing a supplier. Understanding such aspects as laundering and manufacturers data will help you make informed choices of a personal protective apparel (PPA) supplier.
Fluid resistance and tapered sleeves with fitted cuffs are just two criteria to consider when selecting a PPA supplier. A clean, lint-free fabric is also necessary to eliminate particulates, while air-permeability provides comfort. Splash and spray resistance protect against accidental contact with hazardous chemicals and fluids. A PPA fitted with stainless steel buttons or closures and one that can stand up to a commercial hot-water wash is essential for contamination control. Pocket design also affects contamination control. Gender, an often-overlooked criterion when selecting PPA, needs careful consideration as well because most garments are cut for the male physique.
Particulates from fabric fibers contaminate the air and surrounding surfaces. One hundred percent cotton or polyester-cotton blends produce lint during each wash cycle. Just check the dryer lint trap. That air-blown sheath is shedded cotton, and the more cotton a fabric has, the more lint it sheds.
Synthetic materials, however, give off little if any lint. That’s one reason polyester is so popular. Another is its durability, which makes it excellent for cleanroom garments.
A material’s breaking strength is a good indicator of its propensity to shed lint. Ask a potential lab coat/PPA supplier to provide results of tests under ASTM D 5034-95: Standard Test Method for Breaking Strength and Elongation of Textile Fabrics (Grab Test). This benchmark test for new fabrics measures durability. It also includes repeated washes to gauge strength loss percentage. A fabric losing no more than 5 percent of its strength is controlled-environment worthy.
One of the major drawbacks of polyester and most synthetic fabrics is the lack of air permeability. Thus, lab coats and other types of PPA can make one a little hot under the collar. This is particularly important to PPA users who work at ordinary room temperatures. The workers may leave the PPA unfastened or open, exposing the skin or personal clothing, and increasing the risk of contamination and defeating the purpose of the garment and the controlled environment.
Air-textured polyester, however, increases air permeability. The loom calibration creates air-textured fibers or pockets that allow air to move freely in and out of the fabric. Air-textured polyester fabric has differing air permeability specifications. The ASTM D-737-96 test measures the rate of airflow through a fabric, with the results reported in cubic feet per minute (CFM). The greater the airflow, the more comfortable the garment is to the wearer, and the greater the level of compliance.
PPA with an air permeability of 15 CFM is ideal, and is comparable to an 80/20 polyester-cotton blend; air permeability ratings of 12 CFM and below are less comfortable.
Cotton or blends absorb liquid and potentially contaminate not only the garment but the controlled environment.
Splash- or spray-resistant fabrics provide protection from accidental exposures to chemicals or fluids such as blood or urine, which may be contaminated. The following standards from the American Association of Textile Chemists and Colorists (AATCC; Research Triangle Park, N.C.) determine the aqueous, fluid-resistant properties of fabrics:
- AATCC 127-1998: Water Resistance: Hydrostatic Pressure Test. This test measures the resistance of a fabric to water penetration under hydrostatic pressure. (Scores above 400 mm are desirable);
- AATCC 22-2001: Water Repellency: Spray Test. This test measures the resistance of fabrics to wetting by water. (Spray-rating of five to 100 is desirable); and
- AATCC-42: Impact Penetration Test. This test measures the amount of water, in grams, that penetrates the fabric when subjected to a controlled impact. (Scores of less than 1 gram are desirable.)
Impervious PPA is recommended for laboratory personnel who work regularly with acids and solvents. Also, splash- or spray-resistant garments should be static dissipative. Anti-static material is also important when wearing synthetic PPA and working with instruments and computers.
The relevant fluid transfer management standards (FTMS) are:
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- FTMS 4046-101C: Static Decay: This test measures the time it takes for a highly charged fabric to decrease to within 10 percent of its peak. Less than .01 of a second is ideal; and
- Test Method 76 Surface Resistivity: Dissipative material ranges from 106 to 1011. An ideal surface-resistivity range is 106 to 109.
While not often considered by the PPA manufacturer, the design of the PPA – particularly lab coats – correlates directly to the comfort of the wearer, willingness of the worker to wear PPA as intended and contamination.
With lab coats, unisex styles are a straightforward design but accommodate the shoulder widths and arm lengths of men. Put this same lab coat on most women, and you have baggy shoulders, sleeves that are too long and an uncomfortable fit through the hips and lower body. If the woman is working in a seated position, a straight-cut, unisex lab coat will leave the tops of her legs exposed.
Depending on what percentage of the workforce is female (i.e., more than 50 percent) consider making women’s styles available. With fitted shoulders and shorter arm lengths, a woman’s design provides a comfortable garment that covers the tops of her legs when seated.
Heat It Up
The Centers for Disease Control and Prevention (CDC; Atlanta, Ga.) recommends medical linens be processed at a 160º F wash temperature for a 25-minute cycle to sterilize and decontaminate the garment. The Occupational Safety & Health Administration (OSHA) frequently follows this standard.
A hot-water wash has the added benefit of breaking up the body oils that come from the skin and yellow the fabric, particularly around the neck area. Hot water also makes the PPA look better and last longer.
The alternative, cold- or warm-water wash PPA, requires the use of bleach and high pH to sterilize the garments and maintain appearance. Using chemicals and high pH substantially reduces the life of the PPA, resulting in high cost per wash and frequent replacement of damaged garments.
Tapered and Fitted
Anyone with an imposing cuff has often rolled it up for quick comfort. This bulk at the wrist or forearm, however, can cause spills during a reach as well as contamination by dragging it across various surfaces. Open cuffs can also usher in contamination. Skin or open wounds are particularly at risk. Tapered sleeves with fitted cuffs for over-gloving minimize the chances for accidents when reaching. Moreover, if arms are raised while handling liquids or powders, the design prevents substrates from contacting skin from the forearm to the elbow.
Along with cumbersome cuffs, exposed and concealed zippers are traps for contamination – particularly when the worker reaches or leans over a work table. Buttons can be sources of contamination. Many do not withstand hot water sterilization over time. Once they come off, buttons are difficult to detect. Stainless steel snaps or closures may be sterilized, stand up to laundry chemicals and be seen by a metal detector.
Many garments are available with or without pockets. A PPA with patch pockets can trap contamination, particularly if gloves get stored inside pockets. Moreover, there is the threat of exposure if the apparel is not fluid-resistant. A side vent design puts the pocket outside hip level on each side of the garment, similar to the pockets in a pair of slacks. Contaminants, including powders or fluids, that contact the front of the garment do not drop into patch pockets.
Choose a PPA manufacturer that can provide test results to back its claims and adapt to the changing needs of contamination control. Since 1990, many manufacturers have all but vacated the U.S. market in favor of offshore production. The result was fewer available styles, reduced size range (particularly with fluid-resistant coats), fewer colors and lead times ranging from three to six months for special orders. Be open to U.S.-based specialty manufacturers and those whose products evolved from extensive testing before market introduction.
When considering various fabrics (i.e., cotton, cotton-polyester and polyester, textured polyester and synthetics), factor in construction methods, finishes applied to materials and the wash life expectancy. While garments differ significantly from manufacturer to manufacturer, always ask the garment maker to supply the tested wash life of its products and a copy of its commercial wash instructions.
Dennis Adams is president of DenLine Uniforms Inc. (Quincy, Ill.). Reach him at 217-228-9272.