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Identify exactly what was tested
Find the sample description before looking at the largest number. Was the test object a flat piece of fabric, a seam, or the finished garment? Record the material name, layers and product revision. If a seller provides only a cropped graph, request the complete report.
ASTM D4935 describes a method for testing planar materials under specified far-field conditions. A reference to that method is therefore not, by itself, evidence that a person wearing a shirt was tested. ASTM’s published scope.
Read the frequency information
List the frequencies covered by the report and compare them with the claim you are investigating. A single headline figure cannot describe every frequency. Look for the values across the reported range, the setup and any uncertainty information.
As a hypothetical example, a seller might advertise the highest value in a graph while a shopper needs information about another part of that graph. Ask for the relevant results rather than comparing two products only by their largest advertised number. This example is not a finding about any particular brand.
Ask how the material result relates to the garment
Check which parts contain the shielding material, how seams are constructed, and what remains uncovered. Request documentation for the completed design if the claim concerns the whole garment. Do not convert a fabric attenuation figure into a percentage reduction in a wearer’s overall exposure.
The distinction is visible outside clothing too: SLNT’s material-testing page explicitly separates flat-material results from finished-product evidence. It is a useful example of reading scope, not a test of shielding clothing.
Look for durability information
Ask whether results describe a new sample or one tested after washing and wear. If a seller claims performance after repeated laundering, request the procedure, number of cycles and results. “Washable” and “tested after washing” are different statements.
Before buying, check the exact garment’s washing, drying, storage and repair instructions. Do not borrow care directions from a different textile. Consider whether you can realistically follow those directions throughout the garment’s useful life.
Use a buyer’s evidence checklist
- Exact garment, size and revision identified.
- Complete report available, with laboratory and date.
- Sample type and number of layers stated.
- Frequency range and method explained.
- Finished-garment claims supported separately where needed.
- Any washing or durability claims linked to relevant tests.
- Comfort, fit and return terms checked independently of shielding claims.
An unanswered item is a question to raise with the seller, not proof that the product fails. Conversely, an impressive report title does not answer questions outside its scope.
Keep the purchase decision proportionate
This guide does not rank garments or claim that wearing one prevents illness. It helps you describe the available documentation accurately. Compare the intended function, comfort and limitations before deciding whether a purchase serves your purpose.
Continue with the clothing buying checklist, the interactive clothing lesson, or the clothing directory. Listings are not independent laboratory endorsements.
Sources and editorial method
- ASTM D4935: official scope for planar-material testing
- SLNT: manufacturer-hosted example of material versus finished-product scope
Sources checked 17 October 2026. Manufacturer pages describe their own products; they are not independent endorsements. Checklists and examples are our editorial guidance. We did not conduct product testing for this article. Report a correction.