What disposable coveralls are made of: SMS, microporous film, polypropylene, laminates and FR fabrics

What is each fabric made of, and what is it tested for?

Each manufacturer’s construction wording and the tests it publishes. A blank in a manufacturer’s data is a blank here; no test has been added.

What is the difference between SMS and microporous film?

SMS has no film. Its barrier is the meltblown web, a mat of microfibers fine enough to catch dust and shed a light spray, sandwiched between spunbond layers that give it tear strength. Air passes through it, which is why every SMS sheet talks about heat stress, and why the manufacturer’s capability chart ticks dry particulate and overspray for SMS and nothing wetter. A microporous film coverall puts a continuous film on the non-woven; the film has pores small enough to stop liquid water and large enough to pass water vapor. That is why MicroGuard MP can publish ASTM F903 penetration passes for oils, bleach and caustic, and an air permeability under 0.55 cfm, and SMS cannot. The trade is breathability for a liquid barrier.

One more difference matters on the job. The manufacturer’s seam guide explains that a breathable fabric pumps less air through the needle holes of a serged seam than a film fabric does, and concludes that a breathable garment can give better overall dust protection than a similar non-breathable one even though the film filters better. The fabric number and the garment’s performance are not the same thing.

What makes a chemical splash fabric different?

The construction is proprietary, so the data is the only thing to go on. ChemSplash 1 is described as a hybrid membrane and tested by ISO 6530, the European gutter test that pours a chemical down an inclined swatch and scores penetration and repellency in classes; it scores penetration Class 3 on all nine chemicals listed, with repellency from Class 1 for n-heptane and toluene to Class 3 for the acids. ChemSplash 2 is a multi-layer film tested the American way: ASTM F903 penetration on nineteen ASTM F1001 chemicals, all passes, and ASTM F739 permeation on three gases, reported as breakthrough times of 160, 320 and 20 minutes. PyroGuard CRFR is a bi-laminate with both an F903 penetration time and an F739 breakthrough time for each of forty chemicals. How to read those tables is its own guide.

What makes a biological fabric different?

The tests. ASTM F1670 presses synthetic blood against the fabric and looks for it on the other side; F1671 repeats the test with a bacteriophage, a virus surrogate small enough to model hepatitis B and C and HIV. ViroGuard, a blue microporous fabric, passes both on the fabric. ViroGuard 2, a laminated non-woven with taped seams, passes both on the fabric and on the seams, which is the distinction CDC guidance draws for a wet patient, and it adds an ASTM D6978 result of more than 240 minutes against fentanyl citrate. MicroGuard MP and ChemSplash 1 publish F1670 only; ChemSplash 2 publishes both.

What makes an FR disposable different?

Ordinary polypropylene, microporous and polyethylene coveralls melt. The manufacturer’s catalog lists MicroGuard MP as melt-down in a flammability test, and DuPont says Tyvek 400 will ignite and continue to burn and melt. PyroGuard FR carries a phosphate-based fire retardant that the manufacturer says deprives flames of fuel so the fabric chars; PyroGuard CRFR is a self-extinguishing bi-laminate that does not melt or drip when ignited. Both pass ASTM D6413, the vertical flame test, with char length under 6 inches and after-flame under 2 seconds. The manufacturer is explicit that neither is primary FR clothing: they are worn over FR and arc-rated apparel to keep it clean and to keep flammable liquids off it.

What is Tyvek made of?

High-density polyethylene and nothing else. DuPont describes Tyvek as a 100 percent synthetic material made from high-density polyethylene fibers, spun and bonded under high heat and pressure with no binders; the Tyvek 400 product page calls the fabric flash-spun high-density polyethylene with no films or laminates. Because the fibers are fused rather than glued, tiny perforations remain that pass water vapor, and the random fiber lay gives tear and puncture resistance. DuPont publishes 1.2 oz/yd² basis weight, 5.9 mil thickness, 45 inches of water hydrostatic head and a particle barrier it describes as inherent down to 1.0 micron. It is the one coverall fabric on this page that is not built on polypropylene.