Swimwear Manufacturer: How Do You Make Swimwear That Survives Chlorine, Salt, and Sun?

Your first swimwear drop looks great when it launches.

The red is bright.

The white bikini looks clean.

The elastic sits flat around the leg.

The fit photographs well.

Then customers start using the products.

After repeated pool sessions, one color looks different.

The white bottom becomes more revealing when wet than expected.

The leg opening starts waving.

A strap feels looser after several wears.

Another customer notices color transfer onto a light towel.

Swimwear is a small garment exposed to:

a lot of stress.

It deals with:

• Chlorinated pool water
• Sea water
• Sunlight
• Stretch
• Repeated wet/dry cycles
• Sunscreen and body products
• Frequent washing

Good swimwear therefore needs more than soft stretch fabric. The body fabric, lining, elastic, thread, seams, hardware, fit, colorfastness, opacity, care instructions, and any UPF or recycled-content claims all need to be developed as one system. Nylon/elastane, polyester/elastane, PBT-containing fabrics, and other swim textiles can all work, but fiber content alone does not prove chlorine resistance, colorfastness, UV protection, or long-term recovery.

Swimwear development should begin with one question:

Where and how will the customer actually wear it?

A fashion bikini used mainly at:

the beach

may have different priorities from:

a training swimsuit used in a chlorinated pool several times every week.

Table of Contents

• What Does a Swimwear Manufacturer Make?
• Which Fabrics Work Best for Swimwear?
• Why Do Lining, Elastic, and Thread Matter So Much?
• How Do You Get Swimwear Fit and Support Right?
• How Do You Test Swimwear Before Bulk?
• What MOQ, Cost, and Timing Should You Expect?
• Conclusion

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What Does a Swimwear Manufacturer Make?

Swimwear includes far more than:

bikinis.

A swimwear manufacturer may produce bikini tops and bottoms, one-piece swimsuits, tankinis, rash guards, swim leggings, modest swimwear, men's swim shorts, board shorts, and related beachwear. Each category needs its own fabric, lining, support, fit, and performance specification.

Bikini Tops

Possible constructions include:

• Triangle
• Bandeau
• Halter
• Adjustable strap
• Underband styles
• Removable cup styles

The main development questions include:

• Strap stability
• Underband tension
• Coverage
• Cup shape
• Movement in water

Bikini Bottoms

Coverage may be:

• Full
• Moderate
• Cheeky
• High waist
• High leg

But the pattern needs to control:

both appearance

and:

leg-opening tension.

One-Piece Swimsuits

A one-piece introduces an important additional measurement:

torso length.

A suit can fit the:

bust and hip

while still being too short through:

the body.

Tankinis

Tankinis combine:

more coverage

with:

two-piece flexibility.

The top needs to be checked for:

movement and floating

once in water.

Rash Guards

Rash guards sit between:

swimwear

and:

performance activewear.

Possible priorities include:

• Body coverage
• Stretch
• Sun-protection claims
• Low-friction seams

Swim Leggings

These can be used for:

• Training
• Surf
• Modest swim
• Sun coverage

They need:

• Waist stability
• Recovery
• Wet fit
• Opacity

Modest Swimwear

A modest swim set may combine:

• Long-sleeve top
• Legging
• Tunic-length outer piece
• Head covering

depending on the brand.

The important issue is controlling:

fabric movement in water.

An excessively loose garment can behave very differently:

once submerged.

Men's Swim Shorts

These may use:

• Lightweight woven polyester
• Stretch woven
• Other quick-drying woven directions

Possible inner constructions include:

• Mesh brief
• Stretch liner
• No liner

Structured Swim Tops

Highly structured styles involving:

• Underwire
• Cup sizing
• Molded components

require more specialized bra/swim construction.

For those projects, specialist production capability may be used depending on the design.

Our Production Approach

We manufacture stretch apparel and woven garments through our garment-production operation, including:

• Stretch swimwear
• Rash guards
• Swim leggings
• Swim shorts
• Board shorts

depending on the project.

Highly specialized structured swim constructions may involve:

specialist partner production.

Printing and other specialist processes can also be coordinated through long-term partner workshops.

Which Fabrics Work Best for Swimwear?

Swim fabric needs to perform:

dry

and:

wet.

The correct swim fabric depends on stretch, recovery, chlorine exposure, salt-water exposure, colorfastness, opacity, hand feel, weight, intended use, and care. Nylon/elastane and polyester-based fabrics can both work, but neither should be selected from fiber name alone.

Nylon/Elastane

Nylon/elastane is commonly used for:

fashion swimwear.

Some constructions provide:

• Smooth hand
• Soft surface
• High stretch

It can work well for:

• Bikinis
• Fashion one-pieces
• Resort swim

But:

nylon = premium

is not a reliable technical rule.

The final result depends on:

• Yarn
• Knit
• Elastane
• Dyeing
• Finish

Polyester/Elastane

Polyester-based stretch fabrics can work well for:

• Pool swim
• Printed swimwear
• Training-oriented products

Some are specifically engineered for:

better resistance to repeated pool exposure.

But do not write:

polyester is chlorine-proof.

Chlorine resistance needs to be evaluated on:

the actual textile.

PBT-Containing Swim Fabrics

PBT-containing polyester fabrics are commonly used in:

training swimwear.

They can be developed for:

strong recovery

and:

repeated pool use.

But:

PBT = guaranteed chlorine resistance

is still too absolute.

The actual fabric needs:

testing and supplier documentation.

Recycled Nylon and Polyester

Recycled fibers can be used in:

swim programs.

But recycled content and performance are:

different questions.

A recycled nylon/elastane fabric still needs to meet:

the swimwear performance specification.

Textured and Ribbed Swim Fabrics

These can add:

visual interest.

But rib texture can change:

• Stretch
• Opacity
• Water retention
• Recovery

compared with a smooth fabric.

Test the actual style.

Swim Shorts Fabric

Woven swim shorts may use:

• Polyester woven
• Stretch woven
• Nylon woven

depending on the product.

Again:

woven polyester = quick-dry

should not be treated as an automatic claim.

Drying depends on:

the actual fabric.

Which Fabric Is Best for Chlorinated Pools?

There is no single universal answer.

For frequent pool use, choose fabrics developed for repeated chlorine exposure and verify performance using an appropriate test method rather than assuming chlorine resistance from polyester, PBT, or another fiber name.

ISO 105-E03:2010[^1] specifies a method for determining textile color resistance to:

chlorinated swimming-pool water.

The standard was reviewed and confirmed again in:

2026,

so it remains current.[^1]

Importantly, ISO includes test conditions using active chlorine concentrations of:

50 mg/L and 100 mg/L specifically for swimwear.

That gives a much stronger technical basis than saying:

“This fabric is chlorine resistant because it contains PBT.”

Chlorine Can Affect More Than Color

Pool exposure may affect:

• Color
• Elastane
• Elastic
• Surface
• Fit

depending on the materials.

So colorfastness is only:

one part

of swim durability.

What About Sea Water?

Beach swimwear needs its own consideration.

ISO 105-E02:2013[^2] specifies a method for determining:

colour fastness to sea water.

ISO reviewed and confirmed this standard in 2023.[^2]

That is useful when evaluating:

• Bikinis
• Board shorts
• Resort swimwear
• Surf products

especially when the product uses:

strong or contrasting colors.

Contrast Colors Need Extra Attention

Imagine:

Red body
White binding

or:

Black body
Cream lining.

A fabric may appear stable on its own but still create:

staining or transfer concerns

when combined with a lighter component.

Test the:

complete color combination.

What About Sun Fading?

Swimwear spends long periods in:

direct sunlight.

ISO 105-B02:2014[^3] provides a xenon-arc method for evaluating textile colorfastness to:

artificial light representative of daylight.

ISO reviewed and confirmed the 2014 edition in:

2025,

and it remains the published current standard while a future revision is under development.[^3]

That matters especially for:

• Bright red
• Neon shades
• Deep fashion colors
• Prints

where visible fading can quickly generate:

customer complaints.

Why Do Lining, Elastic, and Thread Matter So Much?

Swimwear has very little fabric hiding:

construction mistakes.

The lining, elastic, thread, seams, hardware, and pad system need to work with the shell fabric through stretch, water exposure, washing, and recovery. There is no single universal material called “swim-grade” that guarantees performance; each component should be selected and tested for the intended environment.

Lining

Lining can help with:

• Opacity
• Support
• Comfort
• Shape

Possible approaches include:

• Front lining
• Partial lining
• Full lining

Does Full Lining Guarantee Wet Opacity?

No.

This is important.

Wet opacity depends on:

• Shell color
• Shell density
• Stretch
• Lining color
• Lining opacity
• Fit

A white swimsuit can still become:

too revealing

if both shell and lining become transparent under:

water + stretch.

So test:

the actual finished sample wet.

Light Colors

White, cream, nude, and pastel colors usually deserve:

extra attention.

Possible solutions include:

• Denser shell
• Appropriate lining
• Double layer
• Different lining shade

depending on the design.

Elastic

Elastic controls:

• Leg openings
• Neckline
• Underband
• Straps

The key properties include:

• Extension
• Recovery
• Resistance to repeated exposure
• Width
• Tension

Do not simply ask the supplier for:

“swim-grade elastic.”

Ask what material it is

and whether it is appropriate for:

the intended pool / beach program.

Elastic Tension

The elastic length relative to:

the fabric opening

needs to be developed carefully.

Too tight:

• Digs into skin
• Distorts fabric

Too loose:

• Gapes
• Waves
• Loses security

Thread

Swimwear seams need to stretch with:

the garment.

But there is no rule that every seam must use:

one special “swim thread.”

Thread selection depends on:

• Seam
• Machine
• Fabric
• Stretch requirement

Stitching

Possible constructions include:

• Overlock
• Coverstitch
• Zigzag
• Other stretch-compatible constructions

The best seam is:

the seam appropriate to that position.

Hardware

Possible hardware includes:

• Rings
• Sliders
• Clasps
• Hooks

Avoid writing:

rust-proof

unless the material and testing support that claim.

A better requirement is:

appropriate corrosion-resistant hardware for the intended swim environment.

Metal components should be evaluated for:

• Corrosion
• Discoloration
• Surface damage
• Staining

Plastic components may avoid some corrosion concerns but still need:

• Strength
• Heat resistance
• UV stability

depending on the application.

Removable Pads

Pads can add:

• Coverage
• Shaping

But check whether they:

• Fold
• Move
• Trap water
• Distort after washing

The pad pocket also needs to be:

easy enough for the customer to use.

How Do You Get Swimwear Fit and Support Right?

Swimwear fit is different from:

ordinary clothing fit.

The garment is close to the body and exposed to:

water

and:

stretch.

Fit should be evaluated both dry and wet. Key points include torso length, coverage, leg opening, strap tension, underband stability, bust support, lining behavior, and how the garment changes once saturated with water.

Start With a Clear Size Chart

Do not simply scale:

activewear

into swimwear.

Important body measurements may include:

• Bust
• Underbust
• Waist
• Hip
• Torso

depending on the style.

One-Piece Torso Length

This is one of the most important measurements.

If the body is too short:

the suit may pull at:

• Shoulder
• Crotch

If it is too long:

the garment may:

• Wrinkle
• Sag

Leg Opening

The leg opening should:

lie cleanly

without:

• Digging
• Gaping

Check it while:

standing,

walking,

and:

sitting.

Bikini Coverage

Do not rely only on terms such as:

cheeky

or:

full coverage.

Define the actual garment dimensions.

Different brands interpret these words:

differently.

Straps

Straps need enough tension to:

stay in place.

Too much tension can:

dig.

Too little can:

slip.

Adjustable hardware can increase:

fit flexibility.

Bust Support

Support may come from:

• Pattern
• Underband
• Lining
• Cup
• Strap
• Underwire

depending on the style.

Do not treat:

larger cup support

as simply:

“add more fabric.”

It is a construction problem.

Wet Fit

Wet testing is extremely useful.

But:

“fabric always relaxes slightly when wet”

is too broad.

Different textiles respond differently.

Instead:

put the actual sample in water

and observe what changes.

Check:

• Sagging
• Strap movement
• Coverage
• Lining
• Waist stability

Movement Testing

Ask the fit model to:

• Walk
• Raise arms
• Bend
• Sit
• Move through swimming-like positions

A suit that looks perfect standing still may:

shift during movement.

How Do You Test Swimwear Before Bulk?

Testing is where the product specification becomes:

evidence.

Separate practical wear tests from laboratory performance tests. Wet fit and opacity can be evaluated on actual samples, while colorfastness, UV-protection claims, and other measurable properties may require standardized testing.

1. Wet Opacity Test

This is a practical product-development test.

Wet the complete garment.

Then inspect it:

• Relaxed
• Stretched
• Under realistic light

especially for:

white and light colors.

Do not evaluate:

fabric swatch only.

2. Wet Fit Test

Put the garment:

in water.

Then check:

• Leg opening
• Waist
• Straps
• Bust
• Torso

after the fabric becomes saturated.

3. Chlorinated-Water Colorfastness

For pool-focused products, ISO 105-E03[^1] gives a standardized approach to evaluating textile color resistance to chlorinated swimming-pool water.

4. Sea-Water Colorfastness

For beach and ocean use, ISO 105-E02[^2] evaluates textile color resistance to immersion in sea water.

5. Light Fastness

ISO 105-B02[^3] can be used to assess textile color response to artificial daylight exposure.

6. Seam and Elastic Evaluation

Stretch:

the finished seam.

Then inspect after:

• Repeated extension
• Wetting
• Washing

Check whether:

• Stitch pops
• Elastic waves
• Edge loses recovery

7. Color Transfer

Contrasting colors should be evaluated carefully.

A dark swimsuit that stains:

a white lining

or:

light cover-up

can create a quality complaint even if the garment itself still looks acceptable.

What About UPF Claims?

Rash guards, long-sleeve swim tops, and modest swimwear often use:

UPF

as a selling point.

But:

UPF is not automatically created by polyester, dark color, or long sleeves.

ASTM D6603-19[^4] is the current active ASTM specification covering labeling of UV-protective textiles.

The labeling framework is based on:

instrumental UV-protection data.[^4]

So if a brand wants to say:

UPF 50+

use:

appropriate test evidence

for the actual product/material program.

Stretch Matters

A fabric can become:

more open

when stretched.

That can influence:

UV transmission.

For a close-fitting rash guard or swimsuit:

evaluate the real use condition.

What About Recycled Swimwear Claims?

Recycled nylon and recycled polyester are common requests.

But:

recycled fiber content

and:

certified recycled claim

are different things.

The Textile Exchange Recycled Claim Standard and Global Recycled Standard[^5] provide third-party systems for:

• Recycled-content verification
• Chain of custody

Textile Exchange released:

RCS 3.0 and GRS 5.0 on July 1, 2026.

The updated versions become mandatory on:

December 31, 2026.[^5]

So if the brand wants to use:

• RCS
• GRS
• Certification marks
• Certified recycled-content claims

confirm the applicable:

certification and claims requirements

before production.

Buying fabric from:

a certified supplier

does not automatically mean:

the finished swimsuit can use every certification claim or logo.

What About Care Instructions?

The original draft said:

rinse after every use, hand wash, dry in shade.

That may be good care advice for some swimsuits.

But it should not automatically become:

the care label for every product.

For U.S. apparel, the FTC Care Labeling Rule[^6] requires covered manufacturers and importers to:

• Provide regular-care instructions
• Provide warnings where needed
• Have a reasonable basis for the instructions

So care should be developed from:

the actual garment.

That means considering:

• Shell fabric
• Lining
• Elastic
• Padding
• Hardware
• Print
• Decoration

together.

Rinsing Advice

For some swim products, advising customers to rinse away:

chlorine,

salt,

and other residues

can be useful.

But separate:

customer-use advice

from:

the legally required care-label instruction.

What MOQ, Cost, and Timing Should You Expect?

Swimwear may use small pieces of fabric.

That does not necessarily make:

production simple.

Cost depends on body fabric, lining, elastic, cups, hardware, print, construction, testing, colors, and order quantity.

Typical Starting MOQ

For our normal programs:

Product	Typical starting point
Stretch swimwear	Around 150 pcs/style
Rash guard	Around 100–150 pcs/style depending on program
Swim leggings	Around 150 pcs/style
Swim shorts	Around 100 pcs/style
Board shorts	Around 100 pcs/style

The final MOQ depends on:

• Fabric
• Colors
• Print
• Hardware
• Size range
• Construction

Fabric

Avoid writing:

PBT always costs more

or:

nylon always costs more.

Actual material cost depends on:

• Composition
• Yarn
• GSM
• Width
• Finish
• Supplier

Lining

Full lining adds:

• Material
• Cutting
• Sewing

But it may be necessary for:

the product specification.

Cups and Padding

Removable cups add:

• Material
• Pocket construction
• Handling

Molded or structured components may add:

more development.

Hardware

Rings, sliders, clasps, and hooks each add:

• Component cost
• Assembly

Custom hardware may introduce:

separate MOQ

and:

tooling.

Prints

Printed swim fabrics can add:

• Artwork development
• Printing
• Color approval

depending on the technique.

Testing

Lab tests for:

• Chlorinated-water colorfastness
• Sea-water colorfastness
• Light fastness
• UPF

add:

cost

and:

time.

Colors

A bikini uses relatively little fabric.

That means a small order divided across:

many custom colors

can make material sourcing inefficient.

Do not assume:

small garment = easy small-color MOQ.

Full Roll vs Small Quantity

Full-roll fabric may provide:

better purchasing economics.

Small cut quantities may cost more.

But do not publish:

small cuts are always double price.

That depends on:

the supplier and fabric.

Sample and Bulk Timing

For swim programs using available materials:

Sampling: approximately 10–14 days

can be a practical range.

Simpler programs may be faster.

Complex projects involving:

• Structured cups
• Custom print
• Special hardware
• Testing

may need more development time.

For standard bulk programs:

approximately 20–30 days

after:

• Final sample approval
• Deposit
• Materials ready

is a typical working range.

Testing and custom material development can extend that.

Payment

For new bulk orders, our normal structure is:

50% before production + 50% before shipment.

How Should a New Swim Brand Build Its First Collection?

Start with:

a small number of silhouettes.

Option 1: Fashion Swim

• Bikini top
• Bikini bottom
• One-piece

Option 2: Active Swim

• One-piece
• Rash guard
• Swim legging

Option 3: Resort Range

• Bikini set
• One-piece
• Men's swim short

Then choose:

one or two core fabric directions.

Test Light Colors First

If the range includes:

white,

cream,

nude,

or:

pastel,

develop those early.

They often reveal:

opacity and lining problems

faster than dark colors.

Develop the Full Color Combination

Do not approve:

red shell

and:

white lining

independently.

Put them together.

Wet them.

Wash them.

Check them again.

Test the Complete Garment

Do not approve only:

the raw fabric report.

A finished swimsuit includes:

• Body fabric
• Lining
• Elastic
• Thread
• Hardware
• Pad

and they all interact.

Green Flags and Red Flags

Green flag	Red flag
Selects fabric for actual pool/beach use	Calls every stretch knit swim fabric
Uses chlorine testing for pool products	Assumes PBT guarantees chlorine resistance
Tests sea-water colorfastness	Tests only normal washing
Checks wet opacity on the finished garment	Assumes full lining means no transparency
Fits samples wet and dry	Fits only on a dry mannequin
Develops elastic tension by opening	Uses one elastic ratio everywhere
Selects corrosion-resistant hardware appropriately	Calls every metal trim rust-proof
Checks contrasting colors together	Approves each color separately
Uses real UPF test data	Claims UPF from polyester or color
Verifies recycled claims and chain of custody	Assumes recycled fabric automatically gives GRS label rights
Bases care instructions on the complete product	Copies one care label onto every swimsuit
Separates practical wear tests from lab tests	Uses informal testing as proof of every marketing claim

Conclusion

Swimwear looks small.

But technically:

it is demanding.

The customer wears it:

close to the body,

stretches it,

gets it wet,

exposes it to chlorine or salt,

puts it in sunlight,

and then repeats the process.

Start with:

the use case.

Is this swimsuit for:

• Resort fashion?
• Beach swimming?
• Frequent pool training?
• Surf?
• Sun coverage?
• Modest swim?

Then choose the fabric.

Do not choose nylon only because:

“it feels premium.”

Do not choose polyester or PBT only because:

“it is chlorine resistant.”

Define the actual requirement.

Then test it.

For pool colorfastness:

use an appropriate chlorinated-water method.

For sea water:

use a sea-water colorfastness method.

For sun fading:

evaluate light fastness.

Next:

develop the hidden parts.

The lining needs to support:

opacity and fit.

The elastic needs:

appropriate recovery and tension.

The seams need to:

stretch.

The hardware needs to suit:

wet use.

Then fit the garment:

dry

and:

wet.

Check:

• Torso
• Leg opening
• Coverage
• Straps
• Bust support
• Waist
• Sagging

after the textile becomes saturated.

For light colors:

test opacity on:

the finished swimsuit,

not only the fabric swatch.

Then control the claims.

If you want to say:

UPF 50+,

support it with UV-protection data.

If you want to say:

recycled, RCS, or GRS,

make sure the material and chain of custody support the exact claim.

And do not turn general swim-care advice into a care label without checking:

the actual product.

Finally:

put the sample in water.

Wear it.

Move in it.

Wash it.

Inspect it again.

Because a swimsuit is not successful because:

it looks good dry on a factory table.

It is successful when the:

fabric, lining, elastic, fit, color, support, and construction continue to work after the customer gets into the water.

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Footnotes & References

[^1]: International Organization for Standardization — ISO 105-E03:2010, Textiles — Tests for Colour Fastness — Part E03: Colour Fastness to Chlorinated Water (Swimming-Pool Water). Specifies a method for assessing textile color resistance to active chlorine at concentrations used for swimming-pool disinfection. ISO specifies 50 mg/L and 100 mg/L test conditions for swimwear. The standard was reviewed and confirmed in 2026 and remains current.
https://www.iso.org/standard/52252.html

[^2]: International Organization for Standardization — ISO 105-E02:2013, Textiles — Tests for Colour Fastness — Part E02: Colour Fastness to Sea Water. Specifies a method for determining resistance of textile colors to immersion in sea water. ISO reviewed and confirmed the standard in 2023, so it remains current.
https://www.iso.org/standard/52231.html

[^3]: International Organization for Standardization — ISO 105-B02:2014, Textiles — Tests for Colour Fastness — Part B02: Colour Fastness to Artificial Light: Xenon Arc Fading Lamp Test. Specifies a method for evaluating the effect of an artificial light source representative of daylight on textile color. ISO reviewed and confirmed the 2014 edition in 2025; a future revision is under development, but the 2014 edition remains the current published standard.
https://www.iso.org/standard/65209.html

[^4]: ASTM International — ASTM D6603-19, Standard Specification for Labeling of UV-Protective Textiles. Provides requirements for labeling textile products intended to protect against UVA and UVB radiation, with UV-protection labeling based on instrumental test data rather than fiber name or visual appearance alone.
https://store.astm.org/standards/d6603

[^5]: Textile Exchange — Recycled Claim Standard (RCS) and Global Recycled Standard (GRS). RCS and GRS provide third-party systems for verifying recycled materials and chain of custody. Textile Exchange released RCS 3.0 and GRS 5.0 on July 1, 2026; the updated versions become mandatory on December 31, 2026. Certified product claims remain subject to applicable certification and claims requirements.
https://www.textileexchange.org/recycled-claim-global-recycled-standard/
https://textileexchange.org/knowledge-center/documents/recycled-claim-standard-rcs/

[^6]: U.S. Federal Trade Commission — Care Labeling Rule, 16 CFR Part 423. Requires covered manufacturers and importers of textile wearing apparel to provide regular-care instructions and warnings where necessary and to have a reasonable basis for those instructions before sale.
https://www.ftc.gov/legal-library/browse/rules/care-labeling-textile-wearing-apparel-certain-piece-goods