How to Compare Cleanroom Protective Coveralls by Particle Shedding and Fabric Performance
The spec sheet says “low particle shedding.” That phrase is worth nothing until you know which test produced it, on which fabric, after how many wash cycles, and in which size bin. I have watched a procurement team sign off on a six-figure garment contract based on a one-page datasheet with a bar chart and no test method printed anywhere on it. Six months later their ISO Class 5 filling line was failing environmental monitoring, and the culprit was the cleanroom protective coveralls they had just switched to. Nobody had asked the right questions. Here is how to ask them.
Start with the garment, not the fabric swatch
Most fabric suppliers test a flat piece of material in a controlled lab and publish beautiful numbers. Your operators do not wear flat pieces of material. They wear a constructed garment with seams, zippers, storm flaps, elastic cuffs, thumb loops, and a collar that rubs against a hood. Every one of those features is a shedding source that a swatch test will never capture.
So when a supplier hands you a particle shedding figure, your first question is: whole garment or swatch? If the answer is swatch, you are looking at a number that describes maybe forty percent of the actual contamination risk. The rest lives in the construction.
Particle shedding: what you should actually be comparing
The two methods worth knowing are the Helmke drum test and the body box test. They measure different things and they are not interchangeable.
The Helmke drum tumbles a garment inside a rotating stainless steel drum and counts the particles that shake loose. Results come back as particles per minute per garment, broken out by size channel — typically 0.3, 0.5, 1.0, and 5.0 microns. It is a mechanical agitation test. It punishes brittle fibers, poor seam finishing, and anything that has been beaten up by laundering.
The body box test puts a live human being inside a chamber and counts particles while they walk, bend, and reach. It captures the shedding that happens when fabric flexes against itself and against skin. It is closer to reality but harder to standardize, which is why some suppliers quietly avoid it.
If you are comparing two garments, compare them on the same method, at the same size channels, with the same agitation parameters. A supplier who reports only “total particles” is hiding the distribution. That 5.0 micron channel matters enormously if you are running a sterile fill line, and the sub-micron channels matter if you are in semiconductor or optical manufacturing.
The number that separates serious suppliers from the rest is shedding after laundering. Ask for data at cycle zero, cycle 25, cycle 50, and cycle 100. A garment that sheds beautifully when new and then falls apart at cycle 30 is not a cleanroom garment. It is a disposable with a marketing department.
Fabric performance: the trade-offs nobody advertises
Here is where the conversation gets uncomfortable, because cleanroom fabric is a stack of compromises and every supplier picks a different point on the curve.
Barrier protection versus breathability is the oldest fight in the industry. A denser, more tightly woven or laminated fabric blocks particles and liquids, but it also traps heat and moisture. Operators in a poorly chosen garment will overheat, sweat, and then start shedding skin cells and hair through the very fabric you paid a premium to install. Heat stress is a contamination event. Do not treat comfort as a soft benefit.
Ask for moisture vapor transmission rate, usually reported in grams per square meter per 24 hours, and compare it against air permeability. A fabric with very low air permeability and very low MVTR is a plastic bag with sleeves. It will test well on shedding and fail in the field because people will unzip it, take it off in the airlock, or simply refuse to wear it properly.
Tensile strength and tear resistance tell you how the garment survives real handling. Look for ASTM D5034 for breaking strength and ASTM D5587 for trapezoid tear. Abrasion resistance, usually Martindale or Taber, predicts how the fabric behaves at the shoulders, knees, and forearms where it rubs against equipment. Thin spots become holes. Holes become particle streams.
Static dissipative performance is non-negotiable in electronics and increasingly relevant in pharmaceutical powder handling. You want surface resistivity figures and, better, static decay time. A fabric that dissipates slowly is nearly as dangerous as one that does not dissipate at all, because the charge has time to build on the operator and discharge into a sensitive device.
Liquid barrier, if your process involves blood, body fluids, or chemical splash, should be referenced to a recognized standard — ASTM F1670 for synthetic blood penetration, ASTM F1671 for viral penetration, or the ANSI/AAMI PB70 barrier levels if you are in healthcare. A supplier who says “fluid resistant” without a standard number is telling you they did not test it.
The seams are where the arguments happen
A coverall is only as clean as its worst seam. Bound seams with folded fabric tape trap fewer loose fibers than serged seams. Ultrasonically welded seams eliminate thread entirely, which removes a whole shedding category, but they can stiffen the garment and crack under repeated flexing. Taped seams add barrier performance and add weight.
Ask for seam-specific shedding data if the supplier has it. Most do not. If they cannot produce it, ask for a sample garment and run your own particle count at the shoulder, chest, and crotch seams. The crotch seam is where the highest flex fatigue occurs and where the most embarrassing failures happen.
What to put in your evaluation spreadsheet
Build a table with the garment as the unit of analysis, not the fabric. Columns should include: test method and standard reference, whole garment versus swatch, particle counts by size channel, shedding at cycles 0, 25, 50, and 100, MVTR, air permeability, hydrostatic head if relevant, tensile and tear strength, abrasion cycles to failure, surface resistivity and decay time, seam construction type, sterilization compatibility if applicable, and the ISO class the garment is validated for.
Then add one column most buyers forget: the name of the lab that ran the test. If the data came from the supplier’s own in-house lab with no third-party verification, treat it as a claim, not a fact. Independent testing is not cheap, but neither is a contaminated batch.
The trap of the lowest price per unit
Disposable coveralls win on sticker price and lose on total cost in most reusable applications. Reusable garments cost more upfront but spread the cost across 50 to 100 launderings, provided the fabric holds up. The crossover point depends on your contamination tolerance, your laundry infrastructure, and how well the garment survives processing. Run the math with shedding degradation built in, not with new-garment performance.
There is also a category of disposable that markets itself as cleanroom-ready without ever being validated for a specific ISO class. If the packaging does not state a class, assume the class is whatever your warehouse happens to be.
A short list of questions that will end most sales calls early
Which standard was used for the shedding test, and was it a whole garment or a swatch? What are the particle counts per size channel, not just the total? How does shedding change after 50 launderings? What is the MVTR, and how does it compare to competing fabrics at the same barrier level? What is the seam construction, and do you have seam-level shedding data? Which ISO class is this garment validated for, and who validated it?
Suppliers who can answer all six without hesitating are the ones worth your time. The rest are selling fabric by the yard and calling it protection. Your cleanroom does not care about the brochure. It cares about what comes off the garment when a human being moves inside it, hour after hour, shift after shift. Compare accordingly.
