Buying questions
Is SMS fabric breathable or waterproof?
Both, within limits. SMS blocks splashes and passes air, which is exactly why it replaced film in medical gowns and why it fails when a buyer expects waterproofing.
At a glance
Specification at a glance
| Structure | Air permeability | Hydrostatic head | Use |
|---|---|---|---|
| S10/M15/S10 (35 gsm) | 60 to 110 l/m²/s | 60 to 90 mm | Light gowns, wraps |
| S15/M15/S15 (45 gsm) | 40 to 80 l/m²/s | 80 to 120 mm | Surgical packs |
| S20/M15/S20 (55 gsm) | 25 to 55 l/m²/s | 100 to 150 mm | Heavy barrier |
| SMS plus film | Near zero | Above 300 mm | Liquid hold, not breathable |
Two numbers, opposite directions
Air permeability measures how easily air passes; hydrostatic head measures how much water column the fabric resists. Raising the meltblown weight or adding a film improves the second and destroys the first. SMS is the compromise point where a garment blocks a splash and still lets sweat vapour out.
What breaks breathability
Too heavy a meltblown core, a coating, a film laminate, or heavy print. Also a seam: an ultrasonically welded seam keeps most of the barrier and most of the breathability, while a taped seam can block both.
Send the question with your specification
Tell us the product, the weight you run now and the market it sells into. We answer with the grade, the test values and the documents you will need.
Questions
Common questions
Is SMS waterproof?
It resists splash up to about 60 to 150 mm hydrostatic head depending on structure. It is not waterproof for immersion or sustained pressure.
Is SMS breathable enough for a gown?
Yes for short procedures. Long procedures in hot rooms usually move to a lighter SMS or a breathable film laminate.
Does colour affect breathability?
Masterbatch colour has little effect. Coatings and prints do.