Every pair of panties sold in the United States carries a label disclosing fibre content, country of origin, and a registered identification number (RN). It is not optional. The rule is set by the Textile Fiber Products Identification Act of 1958 (15 U.S.C. §§ 70 et seq.), enforced by the Federal Trade Commission, and updated as recently as 2014. If you've ever wondered what "92% nylon, 8% spandex" tells you, what an RN number is, or why the country-of-origin tag is sewn separately from the wash-care symbols — this is the article. Sources: FTC, ASTM International, the Federal Register, and the Code of Federal Regulations Title 16, Parts 303 and 423.
The Textile Fiber Products Identification Act, in one paragraph
The Textile Fiber Products Identification Act (TFPIA), passed in 1958 and codified at 15 U.S.C. §§ 70–77, requires that any textile product sold in the United States carry a label stating (a) the percentage by weight of each fibre in the product, (b) the manufacturer's name or registered identification number, and (c) the country of origin where the product was processed or manufactured. The rule is implemented by the FTC’s Rules and Regulations Under the Textile Fiber Products Identification Act at 16 CFR Part 303.
Fibre percentages must be listed in descending order of weight, with each fibre at 5% or more disclosed by its generic fibre name as defined by the FTC's official list. Fibres present below 5% may be aggregated as “other fibres” unless they have a definite functional purpose (in which case they must be named individually). The generic name list is the same one used by ASTM International standard ASTM D7642 for textile fibre identification.
Why the labels say spandex when the package says Lycra
Lycra is a trademark. Spandex is the FTC-approved generic name for the elastomeric polyurethane fibre invented by DuPont chemist Joseph Shivers in 1958 and first sold commercially in 1962. The international generic name is elastane, used in Europe and most non-US markets.
The TFPIA requires the generic name on the label, not the trademark. So your panty label legally must read “spandex” (or “elastane” in EU-issued labels), even when the marketing material calls it Lycra. A brand can add the trademark name in the marketing copy or on a hangtag, but the sewn-in label has to use the generic.
Same rule applies to polyester (generic) versus brand names like Dacron (DuPont) or Trevira (Hoechst); to nylon (generic, originally a DuPont trademark, now in public domain since the 1940s); and to modal (generic name for a regenerated cellulosic fibre) versus the trademarked Lenzing Modal™.
The FTC’s generic fibre name list is published in the Federal Register and updated periodically. As of the 2014 update, the list includes 32 named generic fibres — cotton, wool, silk, linen, ramie, nylon, polyester, acrylic, modacrylic, spandex, elastoester, lyocell, modal, rayon, and so on.
What “92% nylon, 8% spandex” actually tells you
Read the label like a recipe. Listed first means most of the fabric by weight; listed last means least. The proportions tell you how the garment will perform.
Nylon (or polyamide in EU labels) is the structural fibre. It provides tensile strength, smooth hand-feel, low moisture retention, and abrasion resistance. The 1938 DuPont nylon-66 patent (Wallace Carothers, US Patent 2,130,948) is one of the foundational synthetic-fibre patents in the industry. Nylon panty fabric typically runs 80–94% nylon by weight.
Spandex / elastane is the stretch fibre. The Shivers 1958 invention (US Patent 3,179,618) describes a segmented polyurethane that can stretch up to 600% and recover, far exceeding the <100% recovery of natural rubber. In intimates, spandex content of 6–18% provides the four-way stretch that allows a single garment to fit XS through 2X. Below 5%, the garment is essentially non-stretch; at 18%+ it’s in compression-shapewear territory.
The arithmetic: 92/8 nylon-spandex is the standard performance-stretch ratio. 88/12 is a higher-stretch lace or seamless. 95/5 is a more structured fabric. Cotton-rib styles flip the dominant fibre to cotton 92–95%, with spandex 5–8% for stretch recovery. Modal styles use modal 90–94% with the spandex balance.
What the RN number is, and why it’s on every label
The Registered Identification Number (RN) is a unique five-digit number issued free by the FTC to a US business that manufactures, imports, distributes, or sells textile, wool, or fur products. It substitutes for the manufacturer’s name on the label, and once issued it is permanent and never reassigned.
If you see RN 12345 on your panty label, you can look up the legal entity that owns that RN at rn.ftc.gov — the FTC’s public RN search tool. Every Love Libby pair carries the Teri Lingerie RN. The RN database is the single most useful consumer tool the FTC publishes for textile shoppers: it lets you trace an unbranded private-label garment back to the actual manufacturer.
RNs were created in 1959 alongside the TFPIA implementation. WPL numbers (Wool Products Labelling Act numbers) preceded them and remain valid on legacy labels. Both RN and WPL are searchable through the same FTC database.
Country-of-origin labelling: a separate rule, not the TFPIA
The country-of-origin tag is governed by a different federal rule — the Tariff Act of 1930, Section 304 (19 U.S.C. § 1304), enforced by US Customs and Border Protection, with FTC’s Made in USA labeling rule at 16 CFR Part 323 specifically governing the “Made in USA” claim.
Made in USA can only be used when all or virtually all of the product is made in the United States — meaning the final assembly and substantially all components and processing are domestic. The 2021 FTC Made in USA Labeling Rule made violations subject to civil penalties for the first time.
Made in [Country] labels (e.g., Made in Vietnam, Made in Pakistan) indicate the country where the garment was sewn and finished, regardless of where the fibre or yarn was sourced. Country-of-origin labelling is required to be conspicuously and permanently affixed — usually sewn into the back-neck or side-seam tag. Note: many seamless tag-free panties (including most of Love Libby’s seamless ribbed line) print the origin and RN directly onto the inside of the garment in soft-touch ink, since there is literally no tag to sew it to. That printing is legally compliant under 16 CFR 303.5.
The care-label rule: separate again, governed by 16 CFR Part 423
The wash-care symbols on your panty label are governed by the FTC’s Care Labeling Rule at 16 CFR Part 423, originally promulgated in 1971 and most recently amended in 2014. The rule requires that all textile garments sold in the US carry care instructions sufficient for the consumer to clean the garment without harming it.
Care symbols are standardised under ASTM D5489 (Standard Guide for Care Symbols for Care Instructions on Textile Products). The five-symbol system covers wash, bleach, dry, iron, and dry-clean. The international equivalent is ISO 3758, which uses a slightly different symbol set; the US ASTM symbols and the international ISO symbols share most icons but differ on a few specifics.
For panties, the typical wash instruction is machine wash cold, gentle cycle, like colours, with tumble dry low or hang dry. Lace and laser-cut styles benefit from a mesh laundry bag — not a regulatory requirement, just a longevity tip.
What a Love Libby panty label tells you
Take a Cotton Rib Bikini ($6.99) off the hanger, flip it inside out, and you’ll find:
Fibre content: a typical cotton-rib disclosure runs ~94% cotton, 6% spandex — the structural-cotton-with-stretch-recovery ratio. The seamless ribbed tag-free pairs flip to nylon-dominant: ~80–88% nylon, 12–20% spandex. The exact percentages are printed on each individual SKU’s sewn-in or heat-transferred label and on the product detail page.
RN number: the Teri Lingerie registered identification number. This is the legal manufacturer-of-record for the Love Libby line.
Country of origin: most Love Libby seamless and laser-cut pairs are produced offshore in major intimates-manufacturing geographies (Vietnam, Pakistan, China). The cotton-rib and modal lines vary by style. The country tag is permanent.
Care symbols: machine wash cold, gentle, like colours, no bleach, tumble dry low or hang. Standard for all five fabric families.
Every label discloses what the FTC requires; nothing more, nothing less. The fabric families grid on the brand page and the materials glossary tell you the same information in plain English.
How to read any panty label, in 60 seconds
Step 1. Find the fibre percentages. The first-listed fibre is the dominant fabric. The second-listed fibre is almost always the stretch component (spandex in US labels, elastane in EU labels). 5–15% stretch fibre means “normal” intimate stretch. Below 5% is structural; above 15% is shapewear-territory.
Step 2. Find the RN number. Search it at rn.ftc.gov to confirm the actual manufacturer behind the label.
Step 3. Find the country-of-origin tag. Made in USA means the FTC's all-or-virtually-all standard. Made in [Country] means sewn there.
Step 4. Find the care symbols. ASTM D5489 standard, machine wash cold + tumble low or hang for almost all panty fabrics.
Five seconds at the rack saves five years of wondering. The information is required by law to be on the label — you just need to know how to read it.
Why the rules matter, and what they don’t cover
The TFPIA covers fibre identity, not fabric performance. A label that reads “92% nylon, 8% spandex” tells you the fibres but not the knit (jersey vs rib vs mesh vs lace), the gauge, the denier, or the moisture-management treatment. ASTM and AATCC publish performance-test methods (ASTM D5034 for tensile strength, AATCC 195 for moisture management, AATCC 135 for dimensional shrinkage), but those tests are voluntary disclosure for most intimates brands.
The TFPIA also doesn’t cover country-of-origin of the fibre — only the country of garment manufacture. Cotton sourced from a US farm, spun into yarn in India, woven into fabric in China, and sewn into panties in Vietnam is labelled Made in Vietnam. Tracing a fibre’s full supply chain requires programs like the USDA Cotton Incorporated Seal or the Better Cotton Initiative — both voluntary.
What the TFPIA does guarantee: any fibre claim on a label is legally binding. If a panty is labelled 100% cotton and the actual content is 95% cotton + 5% polyester, the manufacturer has committed a TFPIA violation enforceable by the FTC under 15 U.S.C. § 70a(a).
Bottom line: trust the label, but learn to read it
The FTC labelling stack — TFPIA + Tariff Act + Care Rule — is one of the most rigorous textile-disclosure regimes in the world. EU regulations under Regulation (EU) No 1007/2011 are similar in scope; UK regulations follow the EU framework post-Brexit through the Textile Products (Indications of Fibre Composition) Regulations 2012.
Love Libby Panties — like every TFPIA-compliant US intimates brand — discloses fibre content, RN, country of origin, and care instructions on every garment. The fabric families grid on the brand page and the materials glossary translate those labels into plain English: lace is stretch nylon-spandex, mesh is power-net knit, laser-cut is bonded-edge no-show, seamless is circular-knit tag-free, cotton-rib is cotton + 5–8% spandex, modal is Lenzing-grade beech-pulp cellulosic.
Read the label. Look up the RN. Match the cut to the fabric to the occasion. The whole catalogue is built on the same standards the rest of the US intimates industry runs on — and the WBENC seal at the bottom of the brand page tells you that the manufacturer behind every RN-labeled pair is women-owned, women-run, third-party verified. That’s the framework.
Discover more from Love Libby Panties or browse the full Love Libby Panties collection.
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