- Created on Saturday, 02 October 2004 16:39
- Written by Terry Jo Gile, MT(ASCP)MA Ed
- How do you know which lab coat is the best bargain?
- What are the criteria for lab coat fabric that meets OSHA requirements?
- How long will these “new” coats last?
These are just a few of the questions that need to be considered before hopping on the low cost bandwagon. The initial outlay of money for the coat is just the tip of the iceberg. You need to factor in the number of washes and replacement costs to determine if this is truly a bargain or not.
Lab coat material varies by manufacturer. Although OSHA does not mandate a particular type of fabric, it does state in its compliance document CPL 2-2.69 that PPE fabric must meet the American Society for Testing and Materials (ASTM) requirements. Your first question to the purchasing agent should be: “Does the lab coat fabric meet the ASTM requirements?” More than likely, the answer from purchasing will be, “ASTM who?”
Founded in 1898, ASTM International is a not for-profit organization that provides a global forum for the development and publication of voluntary consensus standards for materials, products, systems, and services. Over 30,000 individuals from 100 nations are the members of ASTM International. ASTM provides standards that are accepted and used in research and development, product testing, quality systems, and commercial transactions around the globe.
ASTM recommends evaluation of four characteristics of fabric: water repellency or spray ratings, the Suter hydrostatic pressure test, air permeability and the break test. Each one of these test can tell you how well the fabric is made, whether or not it will meet fluid resistance requirements from OSHA and how durable it will hold up throughout use and washings.
Water Repellency/Spray Rating
Water repellency is the characteristic of fabric to resist wetting. Water is sprayed against the taut surface of a test specimen under controlled conditions, which produces a wetted pattern whose size depends on the relative repellency of the fabric. The evaluation is accomplished by comparing the wetted pattern with pictures on a standard chart. The following are the comparisons:
- 100 (ISO 5) – no sticking or wetting of the upper surface
- 90 (ISO 4) – slight random sticking or wetting of the upper surface
- 80 (ISO 3) – wetting of the upper surface a spray points
- 70 (ISO 2) – partial wetting of the whole upper surface
- 50 (ISO 1) – complete wetting of whole upper surface
- 0 (none) - complete wetting of whole upper and lower surfaces
A superior fabric for a lab coat would be one with a water repellency of 90 or higher.
Suter Hydrostatic Pressure Test
This test measures the resistance of fabrics to the penetration of water under static pressure. It is used primarily for the testing of heavy, closely woven fabrics such as those used in surgical suites. The results of this test depend on the water repellency of the fibers as well as the construction of the fabric. The Suter scale goes from 0 to 1,000 with impervious being 1,000. Suter hydrostatic scores of 860 are common with non-porous surgical material and scores of 24 are common with cotton/polyester blend lab coats.
A superior fabric for a lab coat would be one with a Suter hydrostatic score of 400 or more.
OSHA requires that employees wear PPE whenever there is a potential for spray or splash of blood or other potentially infectious material. Most lab employees work in room temperatures ranging from 60 to 75 degrees Fahrenheit vs., a surgical suite, which has controlled temperatures. Therefore, laboratory coats must have air permeability for comfort, which is important to employee satisfaction and ensures that employees wear the coats and are compliant with the OSHA requirements. Air permeability is measured in cubic feet per minute. Hospital surgical attire that is considered fluid proof has an air porosity of 1; cotton lab coats have an air porosity of 25. This means the cotton lab coat is cooler than the fluid-proof fabric required for hospital surgical attire.
A superior fabric for a lab coat would be one with an air permeability of 10 cubic feet per minute or higher.
The break test is a measurement of the strength of the fabric. Unwashed fabric has the highest break strength. The more the fabric is washed and the conditions under which it is washed (i.e.: detergent, fabric softener, bleach) determines the life of the garment. The break strength of cotton fabric is usually in the 50-60 pound range and a cotton/polyester blend is typically 80 pounds.
A superior fabric for a lab coat would be one with a break strength of 150 or more that holds up under 175 washings with less than a 5% decrease in break strength. What this means is that it will hold up and remain durable through repeated washings.
When determining the cost of the lab coat, one must take into consideration not only the up front cost of the initial purchase, but also the cost per wash and the durability of the fabric. Each manufacturer of lab coats under consideration should provide their coat’s comparison data for water repellency, the Suter hydrostatic pressure test, air permeability and the break test. This information should be the result of testing by an independent textiles testing center to prevent bias in the findings. In addition, you should request how many washings the coat can last before it has to be replaced. Most coats last 75 to 100 washings. A superior coat would last 175 washings or more. All of these factors should be taken into consideration to determine the true cost of the coat. For example:
Coat A costs $23 initially and lasts through 75 washings at $1 each. Therefore the total cost of coat A is $98 for the life of the coat or $1.30 per wash But you will have to purchase two more coats to equal the durability of Coat C for a total outlay of $269.
Coat B costs $27 initially and lasts through 100 washings at $1 each. Therefore the total cost of coat B is $127 for the life of the coat or $1.27 per wash But you will have to purchase one more coat to equal the durability of Coat C for a total outlay of $254.
Coat C costs $35 initially and lasts through 200 washings at $1 each. Therefore the total cost of coat C is $235 for the life of the coat or $1.18 per wash You will not have to purchase any additional coats throughout 200 wash life cycle of the coat so the total outlay of cost is $235.
Lab coat costs cannot only be justified by the initial outlay of the upfront cost but must also include the longevity of the coat in the workplace, its look of cleanliness and durability after repeated washings and its ability to protect the employee from chemicals, blood and body fluids.
The author would like to thank Dr. Elizabeth Easter, Director of the Textile Testing Laboratory at the University of Kentucky for her research completed February 11, 2004, on fluid resistant fabrics for lab coats.
Terry Jo Gile, “The Safety Lady” has a speaking and consulting business focused on helping organizations create safety savvy laboratories. She can be reached through her Web site at www.safetylady.com
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