How to Read a Fiber Composition Label
The fiber composition label sewn into your clothes is the one piece of information about a garment that the law requires to travel with it from the factory to your closet. It names the fibers in the fabric, by percentage, by weight. Knowing how to read it confidently gives you the initial tools to start knowing what you are actually putting on your skin.
A garment with fabric in more than one part gets one section for each part, each with its own composition.
Fibers are listed predominant first and must sum to 100%, give or take a 5% "other fibers" allowance.
"95% organic cotton" reads clean, but the additional "5% elastane" means this garment is a blend and not synthetic-free.
Country of origin here refers to where the garment was cut and sewn, not where the cotton was grown or the fabric woven.
The RN, or Registered Identification Number, names the actual maker or importer, which isn't always the brand on the tag. Look it up in the federal RN database.
How this garment scores against our standard
It doesn't pass. Regardless of how clean "95% organic cotton" reads on its own, the shell is 5% elastane, a synthetic. Jacob Gray Goods lists a product only when its disclosed fabric is synthetic-free.
What the label has to tell you
Three things must appear on the permanent label of textile clothing sold in the US:
- Fiber content by generic name (cotton, polyester, wool, etc.), in order of weight, with each fiber's percentage.
- Country of origin. Where the garment was manufactured.
- Manufacturer, importer, or other dealer, usually shown as an RN (Registered Identification Number) followed by digits, for example "RN 12345." Looking that up at the FTC (Federal Trade Commission) RN database tells you who actually made or imported the garment. The brand name is sometimes not the same as the RN registrant inside the garment.
All three requirements apply only to the fabric. The rest of the garment, including thread, elastic, lining, finishes, sits outside what the law requires.
How to read it
1. Find every section header. A garment with multiple textile components gets multiple sections on the label, each with its own composition. A label that says "Shell: 100% cotton" tells you nothing about the lining unless the lining has its own line. If there is no lining line and the garment has a visible lining, you've found a disclosure gap. Ask the brand.
2. Read the percentages in order of weight. Fibers must be listed predominant first. If the percentages don't sum to 100% (give or take a 5% "other fibers" allowance), something is wrong.
3. Translate trade names to generic names. The label is supposed to use generic names, but trade names appear. We go a little into the weeds here and recognize this language may be new, but rest assured, future articles will dive deeper on what the following materials are.
- Lycra, Elaspan, and Roica are all trade names for spandex (also called elastane). Spandex is a synthetic material.
- Tencel and Lenzing Lyocell are trade names for lyocell. Lyocell is a regenerated cellulose.
- Lenzing Modal is the Lenzing-branded version of modal. Modal is a regenerated cellulose.
- Bamboo, Bamboo Rayon, and Bamboo Viscose all mean viscose. Viscose is a regenerated cellulose. "Bamboo fabric" without a process name is almost always viscose and should be labeled as such.
- Polyamide is nylon. Nylon is a synthetic material.
- Acetate and Triacetate are acetate, a cellulose derivative chemically transformed into a thermoplastic. Functionally synthetic.
4. Read the country of origin and RN. Country tells you where the cutting and sewing happened, not where the fiber was grown or the fabric was woven. An RN lookup reveals the actual entity behind the brand. That can tell you whether a brand makes its own garments or sources them from a generic supplier reselling under multiple labels. If the country of origin is missing entirely, that's a red flag. US law requires it on every textile garment.
Patterns to watch for
Hero fiber framing. The front of the swing tag says "organic cotton" in 48-point type. The composition label inside says "60% cotton, 40% polyester." While this is correct from a reporting perspective, only focusing on the organic cotton isn't telling the full story, making it seem like the article of clothing is synthetic-free, when it is not.
The performance trap. "Performance cotton," "stretch cotton," "all-day comfort cotton" typically signal a cotton-elastane blend, often 92 to 96% cotton and 4 to 8% elastane. The fabric is not 100% cotton. It is a synthetic blend. Worth watching for on adult basics and on stretch-marketed kids' clothing.
Bamboo confusion. "Bamboo," "bamboo fabric," "made from bamboo" almost always mean bamboo viscose. The bamboo cellulose has been chemically dissolved and re-spun. Treat any "bamboo" claim as viscose until the label says otherwise. Common across baby pajamas and toddler basics marketed as "bamboo soft."
The vague blend. "Cotton blend," "wool blend," "linen blend" without percentages is a red flag. If the brand had a clean 80/20 it would say so.
QR codes. Some brands now print QR codes that link to extended product info, including more detailed material disclosures than the permanent label requires. But remember, QR codes are supplemental, they do not replace the physical permanent label, which is still legally required. A QR code that takes you to a "materials" page can be a useful disclosure signal (the brand is going beyond the minimum), but treat its content as marketing copy until you can verify against the physical label.
What the label doesn't cover
The label covers the fabric, not the rest of the garment. A "100% cotton" t-shirt can be sewn with polyester thread, finished with a synthetic anti-wrinkle treatment, and trimmed with a polyester-blend collar facing, and still be labeled correctly. Sewing thread is often polyester. Elastic in waistbands and cuffs is often spandex, including the elastic in baby and kids' pull-on pants, onesies, and diaper-cover bands. Interfacing inside collars and plackets is typically polyester fused with adhesive. Chemical finishes (wrinkle-resistant, stain-resistant, water-repellent, flame-retardant on children's sleepwear) don't appear on the composition label. "Exclusive of decoration" lets brands omit visible ornament (lace, embroidery, contrast trim) from the percentages.
Again, the label is a record of the fabric, not a verdict on the garment.
How Jacob Gray Goods uses this
Jacob Gray Goods uses the fiber composition label as the filter. A product is allowable on the site once we've evaluated that the disclosed fabric meets our synthetic-free baseline, the Natural tier. If no regenerated cellulosics are present and all plant fibers carry organic certification from GOTS (Global Organic Textile Standard) or OCS (Organic Content Standard), the product is additionally labeled into the Pure tier.
We're starting with baby and kids essentials because that's where synthetic fabric meets the most vulnerable skin. Baby and toddler skin is thinner and more permeable than adult skin, and the chemicals used to manufacture and finish synthetic fibers and fabrics are associated with endocrine disruption. We don't yet have the full picture of what that exposure does over a lifetime of growing, but the precautionary case for the youngest wearers is strong enough to act now.
We filter only on disclosed fabric composition because the fabric is the bulk of the garment and it's the only piece every brand is required to declare. Thread, elastic, interfacing, trim, hardware, and chemical finishes are not currently independently verified and are not universally declared. Pushing the industry to disclose more than the fabric is the longer goal. Until then, our goal is a clothing marketplace where every product is verifiably synthetic-free at the fabric level. Let us do the leg-work, so you can confidently wear synthetic-free clothing.