Nonwoven Test Methods: Reading ISO 9073 for Gowns and Linens

Nonwoven Test Methods: Reading ISO 9073 for Gowns and Linens

Quick summary: ISO 9073 is the series of test methods for nonwovens. It defines how mass per unit area, tensile strength, tear resistance and bending length are measured, and those four figures sit behind almost every gown, cap, sheet and drape specification a clinic is asked to approve. Reading the method name next to a number is what tells you whether two supplier figures can be compared.

A purchasing manager receives a gown specification that reads: 40 gsm SMMS, Level 2. Another supplier sends 45 gsm SMS. The numbers look close enough to treat as equivalent, and in practice the two fabrics may behave quite differently — one may tear at the shoulder while the other holds, one may drape stiffly while the other moves with the wearer.

The reason is that a nonwoven is not defined by its weight. It is defined by a set of properties, and each property has its own test method. ISO 9073 is the series that defines most of them, and once you know which part covers what, a specification sheet stops being a list of numbers and starts being a description.

Why Do Nonwovens Get Their Own Test Series?

A woven fabric has an obvious internal logic: warp and weft, a repeat, a structure that can be described and predicted. A nonwoven has none of that. Fibres are laid down and bonded, whether by thermal calendering, mechanical entanglement or chemical binders, and the resulting sheet is closer to a felt than to a cloth.

Medical nonwovens are usually polypropylene. A spunbond layer gives strength and integrity; a meltblown layer gives fine fibres and barrier behaviour; a line that runs both, or that laminates them, produces the composites known as SMS and SMMS. Because the structure is not predictive in the way a weave is, the properties have to be measured directly rather than inferred, and that is what the ISO 9073 series does.

What Does ISO 9073-1 Measure?

Part 1 determines mass per unit area. It is the number buyers recognise as grams per square metre, and it is the most quoted figure in medical textile specifications because it correlates broadly with hand feel, opacity, tensile behaviour and, ultimately, cost.

Its limits are worth stating plainly. Mass per unit area is a weight, not a grade. It says nothing about how well the fibres are bonded, how the fabric behaves when it is wet, or how much liquid it will resist. A specification that presents gsm as the whole performance story is describing the raw material load rather than the product.

How Are Tensile Strength and Elongation Tested?

Part 3 determines tensile strength and elongation at break using the strip method. The standard defines two specimen widths, Option A at 25 mm and Option B at 50 mm, and both are run on a constant rate of extension tester. The test reports the force at break and the elongation at that point, which together describe how the fabric stretches before it gives way.

ASTM D5034 approaches the same property differently. In the grab test, only the centre portion of the specimen is gripped and the fabric shoulders carry part of the load. Strip and grab results are not interchangeable numbers, because the specimen geometry and the load path differ. That is why a specification should name the method: 40 N on a strip specimen and 40 N on a grab specimen are not the same claim.

Conditioning matters here too. Textile results depend on the temperature and humidity at which specimens were prepared, which is why ASTM D1776 defines a standard atmosphere for conditioning and testing. A laboratory that skips that step is reporting a number, not a comparable result.

Why Does Tear Resistance Matter on a Gown or a Sheet?

Tensile strength describes what happens when a fabric is pulled evenly across its width. Tear resistance describes what happens when the load is concentrated at a point where a tear has already started. Those are different failure modes, and protective textiles tend to experience the second one.

Think about where a gown fails: at a tie being knotted, at a shoulder as it is pulled on, at the neck binding. Think about where a bed sheet fails: at a corner pulled over a mattress, or where a bed rail catches the edge. In each case the force is concentrated rather than distributed.

ISO 9073-4 determines tear resistance by the trapezoid procedure, and ASTM D5733 applies the same trapezoid principle to nonwovens. Running both tensile and tear on the same fabric is normal practice, because a material that performs well on one can still be weak on the other — particularly when bonding is uneven or the fibre orientation is strongly directional.

What About Thickness and Bending Length?

Thickness is measured under ASTM D1777, which specifies the pressure applied during measurement because a nonwoven compresses under load. Thickness influences barrier behaviour, stiffness and the volume a packed product occupies in a storeroom, which is a real cost line for a facility holding weeks of stock.

Part 7 of ISO 9073 determines bending length, from which the flexural rigidity of the nonwoven can be calculated. This is the technical expression of drape. A fabric with a long bending length holds its shape and feels stiff; a short one conforms and moves. Gowns and linens sit at different points on that scale by design, and a specification that omits it leaves the choice to guesswork.

Which Method Sits Behind Which Specification Figure?

Two conventions help when you are comparing quotes. First, results are usually reported separately for the machine direction and the cross direction, because fibre orientation makes a nonwoven behave differently along and across the web; a single figure is a simplification. Second, garment-level performance is described in ASTM F2407, the standard specification for surgical gowns intended for use in healthcare facilities. Material test data supports a garment claim; it does not replace it.

If a batch is being accepted on the basis of a certificate rather than a full test programme, the sampling plan governs how much confidence that certificate carries. ISO 2859-1 describes sampling procedures for inspection by attributes, and the number of units inspected should appear alongside the result.

How Should a Buyer Read a Nonwoven Specification?

Four questions turn a specification sheet into a purchasing decision.

• Which property is actually constrained by my task? A gown used for brief, light-splash care tasks has different requirements from one used in a decontamination room.
• Which method produced each number? Strip against grab, trapezoid against strip, nominal against measured.
• Is the figure for the material or the finished product? Seams, bindings and ties are where garments fail, and they are not covered by fabric tests.
• What happens at the ends of the range? A specification with a target and no tolerance tells you nothing about batch-to-batch variation.

The materials behind those questions are described in more detail in our note on what gsm means in medical nonwovens and in the comparison of SMMS, SMS and spunbond gown materials. Our Level 1 non-woven fluid-resistant gowns cover routine care tasks, 24-inch non-woven bouffant caps handle hair containment in procedure and food-handling settings, and non-woven bed sheets in 36 by 80 inch format are the highest-volume nonwoven a long-term care home buys. The isolation gowns collection groups the garment range, and the wholesale ordering desk consolidates orders across sites.

Where these products end up being used is described in infection prevention guidance rather than in fabric standards. Public Health Ontario's IPAC core elements checklist sets the expectations for routine and reprocessing activities, and the companion reprocessing checklist covers the decontamination area.

References and standards cited

1. ISO 9073-1 Nonwovens — Test methods — Part 1: Determination of mass per unit area (link checked 21 September 2026)
2. ISO 9073-3 Nonwovens — Test methods — Part 3: Determination of tensile strength and elongation at break using the strip method (link checked 21 September 2026)
3. ISO 9073-4 Nonwovens — Test methods — Part 4: Determination of tear resistance by the trapezoid procedure (link checked 21 September 2026)
4. ISO 9073-7 Nonwovens — Test methods — Part 7: Determination of bending length (link checked 21 September 2026)
5. ASTM D5034 Standard Test Method for Breaking Strength and Elongation of Textile Fabrics (Grab Test) (link checked 21 September 2026)
6. ASTM D5733 Standard Test Method for Tearing Strength of Nonwoven Fabrics by the Trapezoid Procedure (link checked 21 September 2026)
7. ASTM D1777 Standard Test Method for Thickness of Textile Materials (link checked 21 September 2026)
8. ASTM D1776/D1776M Practice for Conditioning and Testing Textiles (link checked 21 September 2026)
9. ASTM F2407 Standard Specification for Surgical Gowns Intended for Use in Healthcare Facilities (link checked 21 September 2026)
10. ASTM F903 Standard Test Method for Resistance of Materials Used in Protective Clothing to Penetration by Liquids (link checked 21 September 2026)
11. ISO 2859-1 Sampling Procedures for Inspection by Attributes (link checked 21 September 2026)
12. What Is GSM in Medical Nonwovens? Weight, Barrier and Comfort (link checked 21 September 2026)
13. SMMS vs SMS vs Spunbond: Choosing Isolation Gown Material (link checked 21 September 2026)
14. Public Health Ontario — IPAC Checklist for Dental Practice: Core Elements (link checked 21 September 2026)
15. Public Health Ontario — IPAC Checklist for Dental Practice: Reprocessing (link checked 21 September 2026)
16. Health Canada — Medical Devices Regulations (SOR/98-282) (link checked 21 September 2026)
17. Lay-Up Compound Matrices for Application of Medical Protective Clothing: Manufacturing Techniques and Property Evaluations. Polymers (Basel). 2022 (link checked 21 September 2026)
18. Polymer-Based Electrospun Nanofibers for Biomedical Applications. Nanomaterials (Basel). 2018 (link checked 21 September 2026)
19. Personal Protective Equipment in Animal Research. Comp Med. 2017 (link checked 21 September 2026)

Buying for a facility rather than a single practice? Request a B2B quote and we will price your volume with Canadian warehouse delivery.

Related Reading

• Learning Hub — clinical and procurement guides
• Isolation gowns collection
• Disposable versus reusable LTC bed linens: cost analysis for Canada
• Bouffant caps explained: non-woven fabric, fit and 24-inch size
• Level 1 non-woven fluid-resistant isolation gowns
• Bouffant caps, 24-inch, non-woven
• Disposable non-woven bed sheets, 36 × 80 inch
• Wholesale and multi-site ordering desk

Frequently Asked Questions

What is a nonwoven fabric?

A nonwoven is a sheet of fibres bonded together by mechanical, thermal or chemical means rather than by weaving or knitting. Medical nonwovens are typically made from polypropylene, formed in a spunbond process for strength, a meltblown process for fine fibres and barrier, or a combination of the two in the same line to give a composite such as SMS or SMMS.

Why does ISO 9073 have so many parts?

Because a nonwoven has no single defining property. Its mass per unit area, tensile strength, tear resistance, bending length, thickness and liquid behaviour are all separate characteristics that can be measured independently, and each part of the series addresses one of them. A specification that quotes one number is describing one property, not the fabric.

What does ISO 9073-1 measure?

It determines the mass per unit area of a nonwoven, which is the number buyers know as grams per square metre or gsm. It is the most quoted figure in medical textile specifications because it correlates broadly with hand feel, opacity, strength and cost — but it is a weight, not a performance grade.

How is tensile strength tested on a nonwoven?

ISO 9073-3 determines tensile strength and elongation at break using the strip method, with two specimen widths defined as Option A at 25 mm and Option B at 50 mm, run on a constant rate of extension tester. ASTM D5034 covers the grab test, where only the centre portion of the specimen is gripped. Strip and grab results are not comparable, so a specification should say which was used.

Why does tear resistance matter for gowns and sheets?

Because textiles fail at a point of stress rather than uniformly. A gown tie, a shoulder seam or a sheet pulled across a mattress edge concentrates force over a small area. ISO 9073-4 determines tear resistance by the trapezoid procedure, and ASTM D5733 covers the same trapezoid principle for nonwovens. Tear strength and tensile strength describe different failure modes.

What is bending length used for?

ISO 9073-7 determines the bending length of a nonwoven, from which the flexural rigidity of the material can be calculated. Practically it describes how much the fabric drapes or holds a shape, which matters for how a gown hangs on a wearer and how a bed sheet stays in place.

Does a higher gsm always mean a better product?

No. Mass per unit area is one input among several. A well-formed lighter fabric can outperform a heavy, poorly bonded one on tear resistance and liquid behaviour, and the process used to make it matters as much as the weight. Application requirements, not a single number, should drive the choice.

What should a supplier include on a nonwoven specification sheet?

The fibre and construction, the mass per unit area and which test method produced it, the tensile and tear results with the method named, the thickness, and any liquid penetration results for protective garments. Naming the method and the conditioning practice is what makes two suppliers' numbers comparable.

Last updated: September 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).