How we check what a garment is actually made of

The short version of how fabric is tested

A garment is bought at retail and documented. An accredited laboratory identifies its fibers by microscopy and solubility, then separates and weighs them by dissolution under ISO 1833 and AATCC 20A. The result is a weight percentage produced by a scale, published next to what the label claimed, on a stated date, by a named method. It is destructive, so it describes the product rather than your specific item. We pay for it, brands never do, and when we have not tested something we say so.

Checked, not guessed. The rest of this page is what the checking consists of.

Step one: someone buys the garment

Verification starts with a purchase, not a request. We buy the garment at retail, the same way you would, and we pay full price for it.

That sounds like a small detail. It is the load-bearing one. A garment supplied by a brand for testing is a garment the brand selected, and a selected sample tells you about the selection more than about the production run. Anonymous retail purchase removes that problem before the lab is ever involved.

Chain of custody is the paperwork answer to a plain question: can anyone prove the item the lab cut up is the item that was bought? So a record travels with the garment, and it covers:

• the retailer, the channel (in store or online), and the date of purchase
• the receipt and the price paid
• the barcode, usually an EAN or UPC from the price tag
• photographs of the swing tag and the sewn-in care label, including the fiber claim exactly as printed
• the lot, batch, or style code where the garment carries one
• a sealed, labeled package from that point until the lab opens it

Everything after this step is chemistry. This step is bookkeeping, and it is what makes the chemistry mean anything.

Step two: the lab identifies which fibers are present

The first question is not how much. It is what.

Under methods such as AATCC 20, an analyst identifies fibers by their physical and chemical behavior. Microscopy does most of the work, because fibers have faces. Cotton reads as a flat, twisted ribbon. Wool carries overlapping surface scales. Polyester is a smooth, featureless rod. Solubility narrows the rest: a fiber's reaction to a specific reagent at a specific temperature rules candidates in and out, and burn behavior adds a further check.

Notice what the lab is deliberately not doing here. It is not reading the label and confirming it. The label is the claim under examination, so a lab that starts from the tag is testing the tag. Identification runs first precisely so the next step measures what is in the fabric rather than what someone expected to find.

Step three: the lab separates and weighs them

The percentages come from a scale, not an estimate.

Quantitative composition analysis is standardized in the ISO 1833 series and in AATCC 20A, and the principle holds across all of it: dissolve one component, weigh what survives. The sample is conditioned to a standard moisture level and weighed. A reagent is chosen that dissolves one fiber type and leaves the other intact. What remains is rinsed, dried, conditioned again, and weighed. The difference between the two weights is the dissolved fiber's share, corrected for the small amount of mass the surviving fiber loses in the reagent, which the standards account for with published correction factors.

This is gravimetric analysis, about as close to arithmetic as testing gets. Each fiber pairing has its own prescribed solvent and its own prescribed math, which is why a real lab report names the exact method it used rather than saying "tested" and leaving it there.

Two details worth knowing about what the number describes. Composition is reported by weight, not by how much of a fiber you can see or feel, so a small percentage of elastane can change how a garment behaves without moving the headline much. And a garment is not one material: trims, elastic, interlinings, and coatings are handled separately under the methods, so a report specifies which part of the garment was analyzed. A result for the main body fabric is a result for the main body fabric.

Why the test destroys the sample, and why it was not your garment

To run the test above, a piece of fabric is cut out, weighed, and dissolved. It does not come back.

That single fact explains most of how Lynen works. Testing is destructive, so laboratories test representative samples of a product rather than the specific item in anyone's hands. Your sweater cannot be verified without ruining your sweater.

So here is the honest boundary on every result we publish. It is strong evidence about that product, not a certificate for your individual garment. Fiber content can drift between production runs, factories, and seasons, and each result carries the date and the method behind it so you can see how current it is. We would rather state that limit clearly than let "verified" imply more than the chemistry supports.

What "accredited" means, and what it does not

Accredited is the second word that gets printed too easily, so it is worth being specific.

ISO 17025 is the international standard for the competence of testing laboratories. A lab holding it has been assessed by an outside accreditation body against requirements covering staff competence, equipment calibration, method validation, sample handling, measurement uncertainty, and record keeping, and it is reassessed on a schedule rather than approved once and left alone.

The part most people miss: accreditation is scoped. A laboratory is accredited for named methods, not in general. The useful question is never "is this lab accredited", it is "is this lab accredited for this method, on this material". That scope is what we check when we commission work.

Every published result names the laboratory partner, the method used, and the date the work was completed. As coverage grows, each result is also gaining the accreditation body, the accreditation scope covering the method, and the number of specimens tested. Turnaround from purchase to published result runs five to ten business days at the bench, plus purchasing and review.

Which brings us to the thing we repeat wherever it is relevant. Today, Lynen does not operate a laboratory. We commission independent accredited laboratories and publish what they report. As Lynen grows, we intend to build a laboratory of our own and bring testing in-house.

What counts as a discrepancy

Not every difference between a label and a lab result is a finding. Textile manufacturing carries real variation, and most labeling regulations allow a tolerance of a few percent for exactly that reason. A garment labeled 95% cotton and 5% elastane that tests a point or two off is a normal garment.

A discrepancy is a meaningful gap. A label reading 100% cotton against a tested result of 52% polyester is a discrepancy. So is an undeclared fiber that someone might react to, even in a small share.

We show the tested numbers next to the claimed numbers either way, rather than compressing a result into a pass or fail badge. You can see the size of the gap and decide what it means for what you are buying.

Two things a discrepancy does not do. It does not establish intent: a tested garment failing to match its label tells you what you are wearing, and nothing about who knew what. And it does not automatically describe every unit of that product, for the sampling reasons above.

No discrepancy is published from a single test. When a first result disagrees with a label by more than the tolerance regulations allow, a second sample of the same product goes to a different accredited laboratory before anything is published. A single positive test, against realistic base rates and realistic laboratory error, still leaves a meaningful chance that a flagged garment is fine, and the cost of wrongly accusing a brand is many times the cost of one more test. The brand is told before publication and given time to respond.

How long a result stays current

Results carry the date they were tested, and they age visibly: verified, then aging, then lapsed. Every verification is scheduled for retest on a 24-month cadence, and signals pull that forward: a reported reaction, a spike in requests on an already-verified item, a reformulation. Fiber content drifts between production runs, so a result describes what was on the rack on a stated date, not a permanent property of a product name.

If you avoid certain fibers because your skin is calmer without them, an undeclared fiber is the detail that matters most, since synthetics trap heat and moisture against skin in a way breathable fibers do not. That is general wellness information drawn from published research rather than medical advice. For a diagnosed condition, your dermatologist knows your skin and we do not.

What a composition test does not cover

A composition test answers what the fabric is made of. It does not screen the chemistry applied to it.

Roughly 8,000 chemicals are used across textile manufacturing, a count attributed to the European Chemicals Agency through a second-hand citation, and none of them appear on a care label. Dyes, resins, softeners, and repellent finishes sit outside the scope of ISO 1833 entirely. Finished-product certification is the tool built for that question: OEKO-TEX® Standard 100 tests the finished garment against limits for more than 1,000 substances, and GOTS® covers organic content along with environmental and social criteria through the supply chain. Both issue a number you can look up free in their own public databases, which is the whole point of them. Where a garment carries a valid certificate, we link it next to our own result.

The two answer different questions, and neither replaces the other. Composition tells you what you are wearing. Certification tells you what was done to it.

How coverage grows, and how the queue is set

Every verified garment in Lynen represents a physical laboratory job that someone paid for. That is why coverage grows garment by garment rather than arriving all at once, and why a submitted garment takes weeks rather than minutes.

Submissions set the queue, prioritized by how many people have asked about the same item. That is the clearest signal we get about what people actually want tested, and it beats anything we could rank internally.

The gap being filled is not small. When EU market-surveillance authorities ran the JACOP campaign published in June 2026, 132 garments across eight countries were tested against their own labels, 37% were mislabeled, and 18 products were ordered withdrawn from sale. A Dutch government-commissioned Circle Economy study in 2019 scanned more than 10,000 discarded garments by near-infrared and found 41% of fiber labels likely to mislead. The campaign data also shows where testing earns its keep: blends of natural and man-made fibers failed 64% of the time, against 15% for claims of 100% of a single natural fiber.

Until a garment has been through a lab, it is labeled "not yet verified" in the app. Not estimated, not inferred from a similar product, not scored by a model. When we have not checked, we say so.

Who pays for the testing

We do. Brands do not pay for placement, cannot buy a better result, and cannot have a result removed because they dislike it. There is no arrangement under which a company can influence what its garment tested at.

That structure is the only one that survives contact with reality. A verification service that can be bought is advertising with extra steps, and it would be worth nothing to you the moment you found out. The cost of lab work is real, and we carry it rather than the brands being tested.

What Lynen is not

Stated plainly, in one place:

• Not a laboratory today. We commission independent accredited laboratories and never present their bench work as our own. As Lynen grows, we intend to bring testing in-house.
• Not a certification. There is no Lynen seal, nothing is Lynen-approved, and no garment is certified by us. We report what an accredited lab measured, on a stated date, by a named method.
• Not a brand ranking. Brand-rating apps score companies, and label-scanner apps read the tag back to you. We test garments and show the result next to the claim. A brand with one verified garment has one verified garment, not a grade.
• Not medical advice. Fabric properties are the limit of what we describe.
• Not a guess. Unverified items say "not yet verified" rather than showing a number nobody measured.
• Not a substitute for the passport that is coming. The EU's digital product passport is expected to apply to textiles around 2027, and it will be a genuine improvement in format. It will also remain a brand-declared record, which is the same kind of claim as today's label with more fields. An independent lab result sitting next to a declared record is the complete picture.

What is coming

Wear testing. Pilling and color fading are the top two measured causes of garment failure, according to a UK WRAP and Defra survey analyzed in the Journal of Cleaner Production in 2022, and standard lab methods for both have existed for decades. They are simply never shown at retail.

Wear testing is coming to verified garments. It is not live today, and we are not going to describe it as though it were. Where wear-test data exists for a garment, you will see it alongside composition, and that coverage will grow the way composition coverage grows: garment by garment, with submissions setting the queue.