If you’ve ever spent a day at the beach or by the pool only to notice that your once-vibrant swim trunks or bikini top have faded unevenly, or worse, left streaks of blue on your skin or a light-colored towel, you already know how crucial color-fastness is in swim fabric. As a swim fabric supplier who’s spent the last 12 years testing, sourcing, and perfecting materials for brands big and small, I can’t tell you how many times a new client has come to us with horror stories of previous gear running or fading after just a few uses. Today, I want to break down what color-fastness actually means for swim fabrics, why it matters more than most people realize, and what we do at our shop to ensure every yard of fabric we send out lives up to the standards swimmers, surfers, and active water lovers deserve. Swim Fabric
First, let’s get the basics straight: color-fastness is simply a fabric’s ability to retain its original color without fading, bleeding, or transferring dye when exposed to specific conditions. For swim fabrics, those conditions are way harsher than what your t-shirt or jeans face. We’re talking constant exposure to chlorine, saltwater, UV radiation from the sun, and repeated cycles of sweat, sunscreen, and washing. Most people don’t realize that regular cotton or even basic polyester will fall apart pretty quickly in these environments—cotton absorbs so much water that it becomes heavy, and its dye molecules don’t bind tightly enough to resist chlorine. That’s why you’ll see cheap swimwear fade after one trip to the pool, while high-quality pieces hold their color for years.
Let’s start with the biggest culprit for swim fabric dye damage: chlorine. If you swim in a public pool, chlorine is used to kill bacteria, but it’s a powerful oxidizing agent that attacks dye molecules. Think of it like bleach—just on a smaller, more targeted level. Basic dyes that work for cotton won’t stand up to chlorine because they’re designed to bond to natural fibers with hydrogen bonds, which chlorine can break. For synthetic fibers like polyester, which is the most common fabric used in performance swimwear, we use disperse dyes. These dyes are tiny, so they can penetrate the tight molecular structure of polyester and form covalent bonds—much stronger than hydrogen bonds—that don’t wash out easily when exposed to chlorine. But not all disperse dyes are created equal. Some cheap brands use low-grade disperse dyes that will bleed when wet, especially in warm water, while we source dyes that are specifically formulated for chlorine resistance, tested to survive up to 50 hours of continuous pool exposure without fading more than 1 Delta E (that’s the standard color difference measurement, where anything under 2 is undetectable to the human eye).
Saltwater is another big one, especially for surfwear or swimsuits made for oceans or lakes with high salt content. Salt is hygroscopic, meaning it pulls moisture out of the fabric’s fibers, and it can also act as a catalyst for dye molecules to break free, especially when combined with sun and wind. We’ve tested some swim fabrics that fade 3x faster in saltwater than in freshwater pools, which is why we developed a specialized line of salt-resistant swim fabric a few years ago. We worked with our dye manufacturers to add a salt-resistant polymer coating that locks the dye in place without making the fabric feel stiff—something that’s a fine line to walk. The last thing swimmers want is a swimsuit that feels like a plastic bag; it still needs to be stretchy, quick-drying, and comfortable. That coating also helps with UV resistance, by the way—another bonus that ties into color-fastness, since UV radiation breaks down dye molecules just like chlorine does.
Sunscreen and sweat are two everyday factors that people often overlook when it comes to color transfer. If you’re applying SPF 50 to your arms and shoulders before a day at the beach, that lotion has chemicals that can lift dye from fabric. I’ve had clients send back swimwear that had bright orange streaks on the chest, only to find out the swimmer had been using a new oil-based sunscreen that didn’t wash out. Sweat has similar effects, especially when combined with salt or chlorine, since it creates a damp environment where dye molecules can move more easily. At our facility, we test for “perspiration color fastness” by soaking fabric in a simulated sweat solution (mixed with salt and lactic acid, which are key components of human sweat) for 48 hours, then rubbing it against a white cotton cloth to see if any dye transfers. Our top-tier fabrics pass this test with zero transfer, which means you won’t be left with stained shoulders after a day on the water.
Washing is another step that’s critical for color retention, even though most people wash swimwear wrong. I see this all the time: someone throws their swim trunks in the washing machine with their regular laundry, uses hot water, and tosses them in the dryer. That’s a surefire way to speed up fading. The high heat breaks down dye bonds, and mixing them with regular laundry means if your swim fabric does bleed, it will stain everything else in the load. We always recommend washing swimwear by hand in cold water with a mild detergent (no bleach, no fabric softener—fabric softener coats fibers and makes them less stretchy, plus it can break down dye) and hanging it to dry. But even with proper care, the fabric itself has to be able to hold up. We test all our fabrics for “wash and wear color fastness” by running them through 20 wash cycles in a standard washing machine, measuring color before and after. Our fabrics retain over 90% of their color after 20 washes, which is 2x the industry standard for performance swimwear.
A common question we get is about printing: what about swimwear with graphics, logos, or patterns? Screen printing, digital printing, and sublimation printing all have different color-fastness properties, and we’ve tested each method extensively. Sublimation printing is our go-to for most custom orders, because it works by turning dye into a gas that bonds directly to the polyester fibers. That means the pattern won’t crack, peel, or fade, even after dozens of washes or exposure to chlorine. Screen printing is great for bold, solid logos, but we use a special water-based ink that’s formulated to resist chlorine and saltwater, so it doesn’t flake off when the fabric stretches. We also test all our printed fabrics for “rub fastness” by rubbing a dry and wet cloth against the printed surface for 10 seconds, checking for dye transfer. Our prints pass with no transfer, which is why some of the biggest surf brands have been using our printed swim fabric for years.
Now, I want to be transparent—no fabric is 100% color-fast forever, and there are factors outside of the fabric’s control. If you leave your swimwear sitting in a damp pool bag for days, that trapped moisture can speed up dye breakdown, because chlorine and bacteria have more time to attack the fibers. Or if you use a harsh detergent or bleach when washing, that will damage the dye. But what we do at our company is build color-fastness into the fabric from the start, not just as a marketing buzzword. We don’t cut corners on dye quality, we test every batch of fabric before it leaves our warehouse, and we work with swimmers and designers to find the right balance between color retention, stretch, comfort, and durability.
As a supplier, we know that our reputation lives or dies by the quality of the fabrics we provide. A brand can have the best design in the world, but if their swimwear fades after a month, they won’t have repeat customers. That’s why we invest so much time and money into testing and refining our products. We recently updated our color-fastness testing process to include simulated UV exposure, since more and more swimmers are spending long days outdoors, and we wanted to make sure our fabrics hold up to harsh sunlight as well.
If you’re a swimwear brand looking for a fabric that will stand out in terms of color vibrancy and long-lasting performance, we’d love to chat. Whether you need a basic solid fabric for core swim trunks, a printed fabric for a new line of bikinis, or a specialized fabric for competitive swimmers who need maximum chlorine resistance, we can customize a solution to fit your needs. We don’t do one-size-fits-all when it comes to swim fabric, and we’re always happy to share test results, samples, or advice on how to get the most out of your fabric’s color-fastness. You can reach out to our team to discuss your specific project, ask questions about color-fastness testing, or request a sample of our top-performing fabrics. We’re here to help you create swimwear that customers will love for years, not just a few uses.
Active Fabric References
- Textile Institute. (2019). Standard Test Methods for Color Fastness of Textiles. Textile Technology Series.
- American Association of Textile Chemists and Colorists (AATCC). (2021). Test Method 61: Color Fastness to Chlorinated Water. AATCC Technical Manual.
- International Organization for Standardization (ISO). (2020). ISO 105-E02: Textiles – Tests for Color Fastness – Part E02: Color Fastness to Sea Water.
- Obermayer, E. (2022). Performance Swim Fabrics: Material Science and Durability. Journal of Textile and Apparel, Technology and Management.
- Surfrider Foundation. (2021). Sustainable Swimwear Guide: Color Fastness and Eco-Friendly Dyeing Practices.
Suzhou Henly Textile Co., Ltd.
Suzhou Henly Textile Co., Ltd. is one of the most professional swim fabric manufacturers and suppliers in China, featured by quality products and good price. We warmly welcome you to wholesale bulk customized swim fabric from our factory. If you have any enquiry about free sample, please feel free to email us.
Address: Room B607, Shimao Business Plaza, No.11 East Minjiang Road, Changshu, Jiangsu, China
E-mail: henly@henlytex.com
WebSite: https://www.henlyfabric.com/
