What swimwear founders need to know about bio-based nylon before their next factory order

The quiet shift in swimwear fiber chemistry

For a decade, the sustainable swimwear conversation has centered on recycled nylon. ECONYL from ghost fishing nets. rPET from plastic bottles. The story was compelling: take ocean waste, spin it into bikinis, save the planet.

But recycled synthetics have a problem that marketing cannot solve. They are still petroleum-based polymers. They still shed microplastic fibers in the wash. They still require PFAS-based finishes for certain performance characteristics. And they still present the same questions about chemical exposure that virgin synthetics do.

Bio-based nylon is the next step. These are polyamides derived not from crude oil, but from plant feedstocks like castor beans, corn starch, and agricultural waste. They perform like traditional nylon. They can be certified OEKO-TEX. And they fundamentally change the input chemistry of your swimwear line.

The technology is no longer theoretical. Brands like Reformation and Lululemon have already integrated bio-based nylon into swimwear and activewear lines. The supply chain exists. The question is whether you understand it well enough to spec it correctly.

How bio-based nylon actually works

The dominant bio-based nylon for apparel applications is PA11, a polyamide derived from castor oil. The chemistry pathway is well-established:

• Castor beans are harvested, primarily in India (which supplies roughly 80% of global castor oil)
• The oil is extracted and cracked to produce undecylenic acid
• Through bromination and amination, this becomes 11-aminoundecanoic acid
• That monomer polymerizes into Nylon 11

The result is a fiber that behaves like conventional nylon but originates from a renewable, non-food-competing crop. Castor plants are drought-tolerant, grow on arid land, require minimal irrigation, and can be harvested multiple times annually.

From a technical standpoint, bio-based PA11 offers some genuine advantages over petroleum-derived nylons:

• Approximately 25% lighter than traditional nylon
• Dries up to 50% faster than conventional polyamide fabrics
• Lower moisture absorption, meaning more stable mechanical properties in humid conditions
• Natural bacteriostatic properties from the castor oil chemistry
• High elasticity with soft hand feel

The leading commercial product in this space is EVO by Fulgar, a 100% bio-based polyamide yarn that has already been adopted by multiple performance apparel brands. According to Fulgar, EVO "combines bio-based origin and high performance, ensuring lightness, elasticity, breathability, fast drying and consistent comfort over time."

Why this matters for swimwear specifically

Swimwear sits at the intersection of several converging regulatory and consumer trends:

PFAS restrictions are accelerating. Australia banned the manufacture, import, and use of PFOS, PFOA, and PFHxS as of July 1, 2025, under the Industrial Chemicals Environmental Management Standard (IChEMS). States like California, New York, Washington, and Maine have passed legislation banning textiles with intentionally added PFAS. The EU's universal PFAS restriction proposal would eliminate most fluorinated finishes from consumer textiles by 2027.

Swimwear has historically used PFAS-based durable water repellent (DWR) finishes for quick-dry performance. If your factory is still applying fluorinated coatings, your product may be unsellable in key markets within 18 months.

Microplastic scrutiny is intensifying. Research from Arizona State University found that on a single July day, microplastic levels in the Salt River increased eightfold, with "most fibers traced back to plastics in swimwear." The study author noted: "Normally, we don't think of our swimsuit as being plastic, but it is a source of synthetic (plastic) fibers."

Separate research from the University of Birmingham provided the first experimental evidence that chemicals present as additives in microplastics can leach into human sweat and then be absorbed through the skin into the bloodstream. The researchers found that sweaty skin was more likely to absorb certain flame retardants than dry skin.

Swimwear is worn in conditions that maximize these exposure pathways: heat, moisture, prolonged skin contact, often in chlorinated or saltwater environments.

Consumer awareness is translating to purchase intent. TikTok and Instagram trend data show rising searches for "non-toxic swimwear," "PFAS-free swimwear," and "sustainable swimwear brands." OEKO-TEX certification has become a proxy for safety in the consumer mind. Brands that cannot substantiate chemical safety claims face increasing reputational and regulatory risk.

Bio-based nylon addresses all three vectors. It originates from renewable feedstock. It can be formulated without PFAS finishes. And it provides a credible, certifiable story for chemical-conscious consumers.

The sourcing reality for brand founders

If you are sourcing swimwear from a factory in China, you need to understand where bio-based nylon fits in the current supply chain.

Availability: EVO and similar bio-based polyamides are produced primarily in Italy and distributed through established textile mills. Your factory may not stock these yarns by default. You will need to specify them in your tech pack and confirm the factory can source them. This may require working with mills that have existing relationships with Fulgar or similar suppliers.

Cost: Bio-based nylon carries a premium over virgin nylon and, in some cases, over recycled nylon. The higher production costs reflect both limited scale and more complex upstream chemistry. Expect to pay 15-30% more for bio-based yarn compared to conventional alternatives. This cost differential should be modeled into your landed cost and pricing strategy before you commit to production.

Minimum order quantities: Because bio-based nylon is not yet commoditized, MOQs for yarn orders may be higher or lead times longer than for standard fabrics. Work with your factory to understand the minimum fabric run and plan your production calendar accordingly.

Blending considerations: Most performance swimwear requires some elastane for stretch and recovery. Bio-based nylon is typically blended with elastane in ratios similar to conventional nylon swimwear (typically 80/20 or 78/22). Ensure your factory understands that the elastane component should also be sourced from a certified supplier, and that the finished fabric should be tested for the full range of restricted substances.

What to spec in your tech pack

When placing an order for bio-based nylon swimwear, your tech pack should include:

• Fiber composition: Specify PA11 bio-based polyamide (e.g., EVO by Fulgar) with percentage and blend ratio
• GSM range: Swimwear typically runs 180-220 GSM depending on construction; bio-based nylon may knit slightly differently, so request swatches before confirming
• Chlorine resistance testing: Specify that the finished fabric must pass chlorine resistance testing to your standard (typically 100+ hours in 10ppm chlorine solution with less than 20% strength loss)
• No PFAS finishes: Explicitly state that no fluorinated water repellent or stain resistant finishes are to be applied
• Certification requirements: Specify OEKO-TEX Standard 100 Class I or II certification for the finished fabric, which ensures testing for PFAS, heavy metals, phthalates, and other restricted substances
• Color fastness: Specify colorfastness to chlorine, salt water, light, and rubbing according to ISO or AATCC standards

The issue is not acute toxicity. It is chronic, cumulative load. Swimwear is worn directly against highly vascularized skin, in conditions that maximize absorption: heat, moisture, repeated exposure over years.

A worked example: Perth founder scenario

Consider a hypothetical founder based in Perth launching a mid-market sustainable swimwear brand. She has been importing from a factory in Jinjiang, Fujian Province, using recycled nylon fabric. Her containers arrive through Fremantle Port, which handles almost all of the container trade for Western Australia and provides the primary gateway for apparel imports into the state.

Her current fabric is ECONYL-based with an OEKO-TEX 100 certification. It is genuinely recycled and tests clean for restricted substances. But she has received inquiries from retail buyers asking about "bio-based" and "plastic-free" options, and she has noticed competitors positioning around plant-derived materials.

Her options:

Option 1: Switch to 100% bio-based nylon. This means sourcing EVO or equivalent yarn, finding a factory with experience knitting PA11 blends, and accepting the cost premium. The benefit is a genuinely differentiated fiber story that addresses both the petroleum-origin and microplastic concerns. The risk is higher cost of goods and potential quality variability if the factory is unfamiliar with the material.

Option 2: Create a hybrid line. Maintain her recycled nylon core collection while introducing a "bio-based" capsule at a higher price point. This allows her to test consumer response without converting her entire supply chain. She can position the bio-based line as a premium offering while continuing to sell the recycled line as a more accessible sustainable option.

Option 3: Wait and watch. Bio-based nylon is still early in its adoption curve. She could monitor the market, track price evolution, and wait for larger brands to establish consumer expectations before making the shift. The risk is being late to a positioning opportunity if bio-based becomes the expected standard in sustainable swimwear.

From a logistics perspective, she would work with a Fremantle-based customs broker to ensure her import documentation reflects the bio-based content claims, particularly given Australia's tightening PFAS regulations. Importers are now "responsible for maintaining clear records that prove their products are compliant," including supplier declarations or lab test results showing that any PFAS present are below allowed trace levels.

Perth's fashion scene, though smaller than its east coast counterparts, has a strong orientation toward sustainable and ethically-made products. Local labels like Empire Rose, Wild Horses, and MAN-TLE have built followings by emphasizing natural fibers, limited production runs, and local manufacturing. A swimwear brand operating from Perth with a bio-based positioning would fit naturally into this community of aligned brands. Perth's emerging sustainable fashion scene offers both a customer base and a network of potential collaborators.

The certification stack for bio-based swimwear

To credibly market bio-based swimwear, you need third-party verification at multiple points:

• DIN CERTCO or equivalent: Certifies the bio-based content of the polymer itself
• OEKO-TEX Standard 100 Class I: Tests the finished fabric for harmful substances including PFAS, heavy metals, formaldehyde, and azo dyes
• GRS (Global Recycled Standard): If you are blending bio-based with recycled content, GRS tracks the recycled input
• ZDHC MRSL conformance: Confirms that no chemicals on the restricted substances list were used in dyeing and finishing

OEKO-TEX certified fabrics are practically PFAS-free. The certification ensures no intentionally added PFAS and testing to verify that any trace contamination is below thresholds.

These certifications are not optional if you are making claims about safety or sustainability. Without them, you are exposed to regulatory enforcement and consumer litigation, particularly in jurisdictions like California where PFAS labeling requirements are tightening.

The performance tradeoff that is not a tradeoff

The traditional argument against sustainable swimwear materials has been that they do not perform as well as conventional synthetics. Cotton absorbs water and loses shape. Bamboo is actually chemically processed rayon. Merino needs synthetic blending to achieve adequate stretch.

Bio-based nylon does not fit this pattern. PA11 from castor oil is a true polyamide. It has the same molecular structure as petroleum-derived nylon. It stretches, recovers, resists chlorine, and maintains shape through repeated wear and wash cycles. The difference is upstream, in the feedstock, not downstream, in the performance.

This is important for founders who have been conditioned to expect a performance tax on sustainable materials. Bio-based nylon is not a compromise. It is a substitution: same performance, different origin.

The one area where bio-based nylon may differ is in chlorine resistance over extended use. Some recycled and bio-based nylons have shown slightly lower resistance to chlorine degradation compared to certain virgin synthetics. This can be mitigated through proper finishing chemistry (without PFAS) and should be tested specifically for your fabric construction.

What factories need to know

If you are bringing bio-based nylon into your production spec, communicate clearly with your factory on these points:

• Yarn sourcing: Confirm the factory can source the specific bio-based yarn you want (EVO or equivalent) and at what lead time
• Knitting parameters: PA11 may require minor adjustments to tension and loop length; ask for knit trials before bulk production
• Finishing chemistry: Specify PFAS-free finishes and confirm the factory has alternatives in place for any water-repellent or antimicrobial treatments
• Testing protocol: Require fabric testing before shipment, including chlorine resistance, colorfastness, and restricted substance screening
• Documentation: Request yarn certificates, fabric test reports, and finishing chemistry declarations for your records

The timeline for adoption

Bio-based nylon is not experimental. It is in production today. But it is not yet the default.

Over the next 24 months, expect:

• Broader mill availability as Fulgar and competitors scale production
• Price compression as volumes increase
• More brands entering the market with bio-based positioning
• Regulatory tailwinds from PFAS bans pushing brands away from fluorinated finishes
• Consumer education as bio-based moves from niche to mainstream

Founders who move now will have a positioning advantage. Those who wait will be competing in a more crowded field with less differentiation.

The bottom line

Bio-based nylon is the next generation of sustainable swimwear fabric. It addresses the petroleum-origin problem that recycled nylon shares with virgin synthetics. It enables PFAS-free finishing. It provides a credible, certifiable story for consumers who are increasingly asking what their swimwear is made of and how it affects their health.

At Ohzehn, we have been working on plant-derived fabric architecture for years. Our 76% bio-based nylon and 24% bio-based stretch fiber represents one approach to this problem. But the broader point is that the industry is moving. The technology is ready. The supply chain is forming. The question for founders is whether they will lead the shift or follow it.

Fabric is not neutral. It is part of your customer's biological environment. The choices you make in your tech pack today determine what sits against their skin for years to come.

Dougie Taylor

Co-Founder, Ohzehn Textiles · Building plastic-free performance apparel