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Chlorine, fit, color fastness: what Miami Swim Week buyers actually scrutinize

9 min read By Dougie Taylor · May 17, 2026

The booth is not the finish line

Hey,

If you're prepping for Miami Swim Week 2026 (May 27-31, if your calendar hasn't auto-updated), you're probably thinking about line sheets, lookbooks, and which influencer might stop by your booth. All reasonable concerns.

But here's what nobody tells first-time exhibitors: the samples you hand to a wholesale or resort buyer often don't stay in their tote bag. They go to a third-party testing lab. And what happens in that lab determines whether you get a PO or a polite follow-up email that never converts.

I watched three brands lose major resort accounts in a single season because their samples failed testing after a promising booth conversation. The buyers liked the aesthetic. They liked the price. They just couldn't put product on the floor that would embarrass them six weeks into a Caribbean summer.

So let's talk about what actually gets tested, and how to prep your samples so they survive scrutiny.

Bucket one: chlorine resistance

This is the test that catches the most brands off guard. A buyer picks up your suit, feels the hand, loves the print. Then they ask the question that separates hobbyists from operators: "What's your chlorine resistance spec?"

If you don't have an answer, you've already lost the conversation.

What buyers actually test

The industry standard for chlorine resistance testing is AATCC Test Method 162, which evaluates colorfastness to chlorinated pool water. The test involves immersing fabric specimens in a solution that simulates pool chlorine at specific concentrations, then measuring color change and stretch retention.

But here's the thing: buyers don't just want to see your lab certificate. Many resort buyers bring sample units back and run their own accelerated tests. They'll soak your suit in chlorine solution for 24-48 hours, then check for three specific failure modes:

The fabric composition equation

Standard nylon-spandex blends (the 80/20 or 82/18 compositions that dominate fashion swim) are vulnerable. Nylon is less chemically stable in chlorine than polyester, and standard elastane degrades under repeated chlorine exposure.

PBT-polyester blends perform significantly better. Lab tests show fabrics with PBT (polybutylene terephthalate) last over 300 hours in chlorinated conditions while maintaining structural integrity. A polyester-PBT blend at 50/50 is essentially what competitive swimwear uses for a reason: the molecular structure resists chlorine attack better than fashion-first compositions.

The trade-off is hand feel. PBT fabrics can feel slightly firmer, less silky than nylon-spandex. But for resort accounts that sell to guests who will wear the same suit in the hotel pool every morning for a week, durability beats drape.

What to prep before Miami

If your current samples are nylon-spandex, run your own chlorine soak test before you ship anything to Miami. Take a sample, soak it in a chlorine solution (2mg/L active chlorine is the European EN13528-2001 standard) for 72 hours, and compare stretch and color to an untreated piece. If there's visible degradation, you have a problem you need to solve before the show.

Ask your mill for a chlorine resistance data sheet. If they can't provide one, that's a red flag about the technical depth of your supply chain.

Bucket two: fit consistency across the size run

Here's a failure mode that doesn't show up in fabric testing but kills wholesale relationships: inconsistent fit across sizes.

A buyer orders a size run. The size 6 fits beautifully. The size 14 fits like a compromised version of the size 6, with weird proportions, straps that dig, and a rise that doesn't match the body it's supposed to fit.

Scaled vs. graded patterns

The root cause is almost always pattern scaling versus proper grading. Scaling takes a size 6 pattern and mathematically enlarges it. Grading redraws the pattern at each size point, adjusting torso length, bust placement, and hip curve independently.

"A graded size 20 has a different rise, a different bust apex, and a different hip curve than a scaled-up size 4."

This distinction matters enormously to buyers who sell to diverse bodies. If your XL fits like a tent because you just made the small bigger, the buyer will notice when they fit-test across their range. And they do fit-test.

What buyers actually check

What to prep before Miami

Bring a full size run of your hero styles to the show. Not just your sample size. Buyers want to see the 2X next to the XS. If you can only afford to make one size run, make it your top-selling style in every size you intend to offer.

Document your grading methodology. If you can explain to a buyer that you work from multiple fit models at different size points, you're signaling that you take fit seriously. If you can't explain your grading, that silence communicates something too.

Bucket three: color fastness after real-world exposure

The third bucket is color retention. And this is where Caribbean resort buyers get especially specific, because they've seen what 30 days of direct sun does to cheap dye jobs.

The sun test failure mode

A guest buys a suit at the resort boutique. She wears it for three weeks. By week two, the vibrant coral has faded to salmon, and by week three it's approaching pink. She's unhappy. She tells other guests. She leaves a review. The boutique buyer remembers which brand failed, and that brand doesn't get reordered.

This is not theoretical. I've had resort buyers describe this exact scenario to me unprompted, usually while explaining why they're cautious about new vendors.

What actually gets tested

Color fastness testing follows AATCC or ISO 105 series standards, depending on the buyer's market. The key tests for swimwear are:

The grades matter. A rating of 5 means no visible change. A rating of 3 means noticeable change that a consumer would see. Below 3, the buyer walks.

The 50-wash benchmark

Some buyers specify a 50-wash standard. They want documentation that your fabric maintains acceptable color after 50 laundry cycles, because that approximates a full season of wear for an active consumer.

If your dye supplier can't provide data on 50-wash retention, you need a different dye supplier or a different fabric.

What to prep before Miami

Request colorfastness data from your mill, specifically for chlorine exposure and light exposure. If the data doesn't exist, commission a test through a third-party lab before the show. The cost of testing is negligible compared to the cost of failing a buyer's post-show validation.

If you're using bright, saturated colors (which perform well at swim shows but are harder to stabilize), be prepared to discuss your dye process. Reactive dyes bond more strongly than direct dyes and generally show higher fastness grades.

The lab report buyers actually want

Let me be specific about documentation. The buyers who take samples to labs want to see:

If you can hand a buyer a single-page tech sheet with this data, you've just differentiated yourself from 80% of the brands at the show who only have a lookbook.

The failure modes nobody talks about

I want to name a few specific failure modes I've seen kill deals after booth conversations:

Ladder runs after one season

This happens when the knit construction is too loose or the yarn quality is inconsistent. A single snag propagates into a visible run that ruins the suit. Buyers who've been burned by this failure check for knit density and ask about yarn source.

Fade after 30 days in Caribbean sun

Direct sunlight in the Caribbean is brutal. A dye job that holds up fine in a temperate climate can fall apart under sustained tropical UV. If you're selling to resort accounts in the Caribbean or similar latitudes, your color fastness requirements are higher than domestic retail.

Stretch loss that makes the suit unwearable

A suit that fits perfectly new but sags after a month of use is a returns problem and a reputation problem. Standard elastane degrades faster than specialty formulations. If your elastane isn't rated for chlorine and UV exposure, expect stretch loss complaints.

Prep timeline for brands showing at Miami Swim Week 2026

With the show running May 27-31, here's a realistic prep timeline:

Now (late May): If you don't have third-party test data, you're out of time to commission new tests before the show. Bring whatever documentation you have and be prepared to explain gaps.

For future shows: Start fabric testing 90 days before any major trade event. That gives you time to commission tests, receive results, and make sourcing changes if needed.

At the show: When a buyer asks about chlorine resistance or color fastness, have a specific answer. "Our fabric is tested to AATCC 162 with a grade 4 or higher on color change" is a real answer. "It's good quality" is not.

The relationship underneath the data

I've framed this whole piece around testing and specs because that's what actually happens in buyer decisions. But underneath all the numbers, there's a relationship question: does this brand understand what we need?

Buyers who serve resort accounts have specific requirements because their end customers have specific use cases. When you demonstrate that you understand chlorine resistance, size grading, and color fastness, you're also demonstrating that you understand their business. That understanding builds trust.

And trust is what gets you from a promising booth conversation to a reorder.

At Ohzehn, we've built our fabric programs around exactly these conversations. Knowing what buyers actually test helped us spec our mills correctly from day one. Not every brand has that advantage starting out, but now you know what to ask.

Good luck at the show. Do the prep work, bring the data, and don't hand a buyer a sample that can't survive the lab.

Cheers,

Dougie

Dougie Taylor
Dougie Taylor
Co-Founder, Ohzehn Textiles · Forbes & Inc. recognized brand operator

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