100% natural vs synthetic blends

Plenty of “merino” and “cotton” clothes are blends: a natural fiber plus some nylon, polyester or elastane. In FabricTruth’s own dataset, 27 of the 89 product labels we checked (30%) are part natural, part not. Here is what the synthetic share does for a garment, what it costs, and how to read the label.

Bottom line

Blends usually wear longer, stretch more and wrinkle less. The cost comes at end of life: blends can’t be separated by mechanical recycling, elastane jams recycling even in small amounts, and the synthetic share doesn’t biodegrade. A cotton-polyester blend did shed fewer fibers in the wash than pure polyester.

Head to head

Criterion	100% natural	Natural-synthetic blend	Which side
Durability^1,2,3	Pure wool yarn had about a third of a nylon yarn’s strength and about seven times its abrasion loss in one lab test.	Brands add nylon for wear: KÜHL labels the 5% nylon in a merino crew “added for durability,” and a 2024 review says polyester adds durability and shape retention to cotton.	Edge: blend
Stretch^3,4	Cotton is only “slightly elastic,” per a 2024 textile review.	Elastane (spandex) is added for stretch, and the more there is, the stretchier the fabric. FTC labeling guidance lets a label name it even under 5% because it has a function.	Edge: blend
Wrinkles^3,5	Cotton is prone to wrinkling, and linen creases more easily still.	A polyester-cotton blend is more wrinkle-resistant and long-wearing, per the same review.	Edge: blend
Wash shedding^6,7,8	Natural fibers shed too, but cotton and wool fibers broke down in degradation tests funded by their industries.	In a lab test, a polyester-cotton blend shed significantly fewer fibers than pure polyester or acrylic. Its polyester fibers are still plastic.	Depends on use
Recycling³	Mechanical recycling works best on single-fiber fabrics such as cotton, linen and wool.	Mechanical recycling can’t separate finely blended fibers, and elastane clogs machinery even at low levels. Chemical separation exists, but the review notes that most companies doing it are new and small.	Edge: 100% natural
End of life⁷	Wool biodegraded readily in a 90-day seawater test (wool-industry funded).	Polyester and nylon showed virtually no biodegradation in the same test, so the synthetic share persists.	Edge: 100% natural
Odor^9,10	Wool, then cotton, held the least odor in wear studies.	Polyester and nylon held the most. We found no odor study of blends specifically.	Depends on use

“Which side” is a plain reading of the cited evidence for that row, not a score. Prices are from product pages on November 2, 2026 and change often.

Counterpoints and caveats

A garment that lasts longer may matter more than its fiber. In one wardrobe survey, synthetic garments were reported to last 6.3 years on average, against 5.3 for 100% wool and 3.6 for 100% cotton. That survey was commissioned by the wool industry.¹¹
The wool-vs-nylon strength test used yarns made for car seat fabric, not clothing, and two of its authors work for an automotive trim company.¹
Shedding varied with wash temperature, detergent and conditioner in complex ways, so “blends shed less” is one lab’s finding, not a rule.⁸
Few textiles of any fiber are recycled today: the same review says only about 15% of US textiles are recycled or donated.³

Short answers

What does “other fiber” mean on a clothing label?

Under FTC labeling rules, fibers under 5% of the weight are generally listed as “other fiber” instead of by name, unless they have a clear function, like spandex for stretch or nylon for durability. Wool must always be named.⁴

Counterpoint: So “97% cotton, 3% other fiber” doesn’t tell you what the 3% is. Our source is an archived edition of the FTC guide, since the current web copy blocked our fetcher.

Can a “100% cotton” label leave out elastic?

Within limits, yes. The FTC guide excludes trim such as waistbands, cuffs and collars, and elastic in the base fabric under 20% of the surface area can be left off if the label adds “exclusive of elastic.”^4,12

Counterpoint: We haven’t measured how often brands rely on this. Industry of All Nations, for one, says its boxers have a recycled elastic waistband of unstated fiber, and we note that on its page.

How common are blends in FabricTruth’s data?

27 of the 89 product labels we checked across 37 brands (30%) are part natural, part not, and another 12 (13%) have no natural fiber at all.¹³

Counterpoint: Our rows are a few core styles per brand, not full catalogs, and 31 of our 120 rows couldn’t be checked, so they aren’t counted. The data study explains the limits.

Are blends harder to recycle?

Yes. Mechanical recycling can’t separate finely blended fibers, and elastane jams shredders even in small amounts. Chemical methods can split cotton from polyester, but the companies doing it are mostly new and small.³

Counterpoint: Single-fiber clothes mostly aren’t recycled either: only about 15% of US textiles are recycled or donated, per the same review.

100% natural options

Scored brands have a natural-fiber share score from the labels we checked; brand pages marked unscored don't have enough checked labels yet. Picks pages list specific products from brands with mixed ranges and are not scored.

Wool&PrinceScored brand100% merino shirts and tees
Alex CraneScored brandAll rows we read were 100% natural
PendletonBrand page (unscored)100% wool shirts
American GiantScored brand100% cotton tees and fleece
Industry of All Nations picksPicks (not scored)Mostly 100% natural; small exceptions noted

Fiber guides: Is merino wool worth it? · Organic cotton guide · Is modal, lyocell or bamboo natural?

Sources

Industry funding is noted where a study was paid for or co-authored by a fiber industry body or brand. Product labels and prices read November 2, 2026.

1Wu, Wang, Wang, Jiang (Donghua University). Highly soft, abrasion-resistant, and moisture-absorbent wool/PA56 blended yarns for seating fabrics. Polymers, 2024. Two authors work for an automotive trim company; the yarns (merino with bio-based nylon PA56) were made for seat fabric, not clothing.
2KÜHL product page. KÜHL Invigoratr Merino Crew: 95% merino wool, 5% nylon “added for durability”, $130. Product label, read Oct 31, 2026, 2026.
3Choudhury, Tsianou, Alexandridis (University at Buffalo). Recycling of blended fabrics for a circular economy of textiles: separation of cotton, polyester, and elastane fibers. Sustainability (review), 2024. Funded by the US National Science Foundation; authors declare no conflicts.
4US Federal Trade Commission. Threading your way through the labeling requirements under the Textile and Wool Acts. Business guidance (archived edition on govinfo.gov; the FTC’s current web copy blocked our fetcher), c. 2006.
5Uğur, Bilgiç. A novel approach for improving wrinkle resistance and flame retardancy properties of linen fabrics. Bilge International Journal of Science and Technology Research, 2017.
6Zambrano et al. (NC State, Cotton Incorporated). Microfibers generated from the laundering of cotton, rayon and polyester based fabrics and their aquatic biodegradation. Marine Pollution Bulletin, 2019. Funded by Cotton Incorporated; two co-authors from Cotton Incorporated.
7Collie, Brorens, Hassan, Fowler (AgResearch). Marine biodegradation behavior of wool and other textile fibers. Water, Air, & Soil Pollution, 2024. Funded by Australian Wool Innovation; fabrics supplied by Woolmark.
8Napper, Thompson (University of Plymouth). Release of synthetic microplastic plastic fibres from domestic washing machines. Marine Pollution Bulletin, 2016.
9Laing (University of Otago). Natural fibres in next-to-skin textiles: current perspectives on human body odour. SN Applied Sciences, 2019.
10McQueen, Laing, Brooks, Niven (University of Otago). Odor intensity in apparel fabrics and the link with bacterial populations. Textile Research Journal, 2007.
11Laitala, Klepp (SIFO, OsloMet), Henry (QUT). Does use matter? Comparison of environmental impacts of clothing based on fiber type. Sustainability, 2018. Co-funded by Australian Wool Innovation and the Research Council of Norway; lifespan data from an AWI-commissioned survey.
12Industry of All Nations product page. Industry of All Nations Wild Boxers: organic cotton body; recycled elastic waistband (fiber not stated). Product label, read Oct 31, 2026, 2026.
13FabricTruth. Fiber labels on men’s brands: what FabricTruth’s dataset shows. Our own dataset and method (CSV published), 2026. Our own data; see its limitations section.

Updated November 2, 2026. More context: Why the label matters · All comparisons