How Fabric Testing Works: Inside a Textile Lab

Have you ever looked at a clothing label and wondered how anyone actually knows what’s in the fabric? The label might say 60% cotton and 40% polyester, but somebody, somewhere, had to measure that.

That somebody works in a textile lab, and fabric testing is a lot less mysterious than it sounds. Here’s what happens when a garment gets tested.

How Do Labs Identify Fibers?

The first step is figuring out which fibers are present. Analysts rely on standardized test methods from organizations like AATCC, using tools such as microscopy and solubility.

Under a microscope, fibers are surprisingly recognizable. Cotton looks like a twisted ribbon, while polyester is a smooth, even rod.

How Do Labs Measure Fiber Percentages?

Measuring exact percentages takes a different approach, and it’s satisfyingly straightforward.

Quantitative fiber analysis, standardized in the ISO 1833 series, works by controlled dissolving. The lab weighs a fabric sample, applies a solvent that dissolves one fiber type while leaving the other intact, then dries and weighs what remains. The difference reveals the dissolved fiber’s share.

Each fiber pairing has its own prescribed solvent and calculation, which is why a lab report cites the exact method number it used. The result isn’t an estimate. It’s a scale, a solvent, and arithmetic.

Why Can’t a Lab Test the Shirt in Your Closet?

Here’s the catch: this kind of testing is destructive. The sample is dissolved in the process, so labs test representative samples of a product rather than the exact unit you own.

That means a result is strong evidence about a product as a whole, not a certificate for your individual garment. Testing also costs real money, which is why independent verification tends to grow product by product.

How Do You Know the Lab Itself Is Reliable?

Good question! Textile testing laboratories can be accredited under ISO/IEC 17025, an international standard for testing and calibration labs. Accreditation means the lab’s methods, equipment, and processes are independently assessed.

They’re the same methods brands and regulators generally use, too.

How Does Lynen Use Fabric Testing?

Lynen doesn’t run a laboratory. We commission independent, accredited labs to test garments using these established methods, then publish the results in the app.

The testing itself has existed for generations. What’s new is putting the answers where you can see them while you shop.

You don’t need a chemistry background to benefit from any of this. The next time you see a verified fiber result, you’ll know what’s behind it: a careful, standardized process in an accredited lab.

Frequently Asked Questions

How do labs test what fabric is made of?

Labs identify fibers with tools like microscopy, then measure percentages through controlled dissolving under standardized methods such as the ISO 1833 series. One fiber is dissolved, what remains is weighed, and the difference reveals each fiber’s share.

Can a lab test the exact garment I own?

Quantitative fiber testing is destructive, so labs generally test representative samples of a product rather than your individual garment. A result is strong evidence about that product as a whole.

What makes a textile lab trustworthy?

Look for accreditation under ISO/IEC 17025, the international standard for testing and calibration laboratories. Accredited labs follow standardized, independently assessed methods, the same ones brands and regulators rely on.