The Promise of Polyester: Criteria to Consider When Selecting Personal Protective Apparel

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.

Coming Clean

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.

Choose Comfort

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.

Accidents Happen

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.