Is Nylon or Polyester Better for Swimwear?

You’re eyeing two great swimsuits, and the tag says one is nylon, the other polyester. Which one dries faster and holds up best? The answer isn’t just about a single property-it’s a blend of science and practicality.

We will break down the fabric face-off, covering how each fiber handles water, their real-world drying speed, chlorine resistance, and long-term care for shape and color.

The Quick Answer: Your Swimwear Fabric Cheat Sheet

Run your fingers over a nylon swimsuit. It feels springy and soft against your skin. Now, feel a polyester one. It has a crisper, slicker hand. That initial touch tells you a lot.

For pure drying speed, polyester wins every time. Its fibers are hydrophobic, meaning they naturally repel water. But fast drying isn’t the whole story for a great swimsuit.

• Nylon: Dries slower, feels more luxurious, resists abrasion from sand and saltwater beautifully. Softer against the skin. More prone to fading from chlorine and sunlight over time.
• Polyester: Dries very fast, fights chlorine fade superbly, often more affordable. Can feel less supple. Excellent UV resistance for long days in the sun.

Can you swim in nylon shorts? Absolutely, if they are a swim-appropriate blend (like 80% nylon, 20% spandex). Are swimsuits made of nylon? Extremely common. It’s a classic, performance-oriented choice. The real magic-and the reason for their differences-happens at a level you can’t see.

Fiber Physics: Why Nylon and Polyester Act Differently in Water

At a molecular level, these fibers are built differently. Imagine nylon has tiny amide groups in its chain. These groups attract and hold onto water molecules, almost like a microscopic sponge. Polyester, on the other hand, is built with ester groups that repel water, acting more like a waxed jacket. This molecular difference is one of the key reasons nylon and polyester fabrics perform differently in various applications.

This core difference dictates everything. Because nylon absorbs a bit of water (about 4-5% moisture regain), it can feel cooler and wick slightly in workout gear. In swimwear, this absorption is why it dries slower. Polyester’s repellency (less than 1% moisture regain) is why water beads up and rolls off its surface, leading to quick drying.

Chlorine resistance is a huge differentiator. Chlorine is a powerful oxidant that attacks dye sites and the fiber itself. Nylon’s chemical structure is more vulnerable to this attack, leading to that familiar faded, dull look. Polyester’s inert structure makes it a chlorine champion, retaining its color and strength much longer in pools. For UV degradation, polyester also generally has the upper hand, though modern nylon is often treated for UV protection.

Neither fiber has the stretch you need for swimwear on its own. That comes from elastane (spandex), typically making up 15-20% of the blend. Nylon has a bit more inherent give than polyester, which is why nylon-spandex blends often feel slightly more forgiving and soft. Both rely on the elastane for snap-back recovery. Always rinse chlorinated water out quickly to protect that elastane from wear and decay.

This is why cotton is a terrible swimwear choice. It soaks up water like a towel (moisture regain of 8%+), becomes heavy, stretches out, and dries painfully slow. It also degrades quickly in sun and chlorine. For winter wear, this physics flips: nylon’s slight absorption can aid in moisture management under layers, while polyester’s repellency is key for waterproof outer shells. In swimwear, a spandex-polyester blend adds stretch and quick-drying performance. This spandex polyester swimwear fabric moves with you and keeps its shape.

The Drying Race: Measuring Moisture Escape

You can test this at home. Take two similar swimsuits, one nylon, one polyester. Rinse them in cool water, gently squeeze (don’t wring), and lay them flat on separate dry towels in the same spot, away from direct heat. Feel them every 30 minutes. The polyester will almost always feel surface-dry first.

The science is in the “moisture regain” I mentioned. Polyester releases the bulk of water from between its fibers and off its surface rapidly. Nylon holds some water within the fiber structure itself, which takes longer to evaporate away, especially when compared to performance nylon fabrics.

Fabric construction can override this. A thick, tightly knit polyester suit will dry slower than a thin, mesh-like nylon one. Always check the fabric weight and texture-a heavy fabric traps more water, regardless of fiber. Waterproof properties of fabrics can further impact drying times in wet conditions. Look for coatings or membranes that repel water while maintaining breathability.

Slow drying means mildew risk. Never ball up a damp suit and toss it in a gym bag. Rinse it, gently press out water, and lay it flat or hang it in the shade to dry completely before storage.

Material Data Table: Swimwear Fabric Specs at a Glance

Property	Nylon (e.g., 80/20 Nylon/Spandex)	Polyester (e.g., 80/20 Polyester/Spandex)
Breathability	Moderate. Can feel slightly clammy when wet due to water retention.	Low. Water repellency means less moisture exchange next to skin.
Shrinkage Rate	Low if washed in cool water. Can be heat-set during manufacturing, but high heat can distort.	Very Low. Excellent resistance to heat-related shrinkage. The more stable fiber.
Heat Tolerance	Fair. Avoid high heat drying; use cool iron if needed.	Good. Can tolerate warmer drying (still, air dry is best), more resistant to heat setting.
Stretch Factor	High (from elastane). Nylon fiber itself has a slight, soft give.	High (from elastane). Polyester fiber is more rigid, so stretch comes solely from the elastane.
Chlorine Resistance	Poor to Fair. Prone to fading and fiber weakening over time.	Excellent. The top choice for frequent pool use.
UV Resistance	Good (when treated). Can degrade with prolonged, intense sun exposure.	Excellent. Inherently more resistant to UV degradation.
Typical Drying Time (Relative)	Slower. Holds moisture within the fiber.	Faster. Repels water from the surface.

Your Swimwear Survival Guide: Washing, Drying, and Repair

Think of your swimsuit as a high-performance athlete. It needs a cooldown and proper recovery after every harsh workout in chlorine, salt, or sun. This routine is non-negotiable for both nylon and polyester blends.

The Post-Swim Protocol: 4 Non-Negotiable Steps

1. Immediate Rinse

   As soon as you’re out of the water, rinse your suit thoroughly under cool, running tap water. I use the shower or a hose. Cool water is key because hot water can set stains and degrade fibers. This step flushes out chlorine, salt, sand, and body oils before they can bond to the fabric. Chlorine is a potent oxidizer that attacks dye molecules and the polyurethane (elastane) fibers that give your suit its stretch, making this rinse the most important thing you can do.

2. Hand-Wash Method

   Once home, give it a proper clean. Fill a basin with cold water and add a small amount of gentle detergent, ideally one made for delicates or technical fabrics. Swish the suit through the water for a few minutes. Never use bleach or detergent with bleach additives, as they will catastrophically yellow nylon and weaken all synthetic fibers. For sunscreen or oil stains, gently rub a drop of the same detergent directly onto the spot before soaking. Never wring or twist the suit, as this permanently distorts the knit and strains the elastic threads.

3. Drying

   Press excess water out by rolling the suit in a clean, absorbent towel. Then, lay it completely flat on a dry towel or a drying rack, reshaping it to its original dimensions. Always dry away from direct sunlight and heat sources like radiators. UV rays and heat are the twin enemies of elastane; they break down the fibers from the inside out, leading to permanent sagging. Polyester dries slightly faster than nylon due to its lower moisture absorption, but both benefit from this air-drying method.

4. Storage

   Never fold a dry suit tightly, especially at the elastic points. This creates permanent creases that weaken the fibers. Instead, hang it by the liner or lay it flat in a drawer. Some of my suits last for years because I simply roll them loosely and store them in a breathable cotton bag.

When Things Go Wrong: Troubleshooting Fade, Snags, and Sag

Even with great care, swimwear faces brutal conditions. Here’s how to handle common issues.

Problem: Chlorine Fade or Yellowing.
You’ll notice this more on vibrant nylon suits, which can turn a dull, yellowish hue. Polyester has superior chlorine resistance. Bleach and chlorine can be harsher on blends like polyester-spandex or nylon, raising the risk of yellowing. For these fabrics, extra caution with any chlorine exposure helps keep colors vivid. If fading occurs, try a vitamin C soak: dissolve crushed vitamin C tablets (ascorbic acid) in cool water and soak the suit for an hour to neutralize chlorine residues, then rinse. Prevention via the immediate rinse protocol is always better.

Problem: Pilling or Snagging.
Nylon’s smooth, round fibers are more prone to snagging on rough surfaces like pool concrete. Small pills can form. Use a battery-operated fabric shaver carefully on a low setting, holding the fabric taut. Prevent this by avoiding sitting directly on abrasive surfaces.

Problem: Loss of Elasticity (Sagging).
This is almost always irreversible elastane degradation from heat, chlorine, or age. You can’t fix it, but you can slow it. Elastane’s lifespan is finite, but rigorous cold-water rinsing and air-drying away from heat will maximize it.

Problem: Dye Bleed from Prints.
This is common with vibrant digital prints on either fabric. Always wash in cold water with a color-catching sheet, and never let a wet, printed suit sit bunched up on itself.

Note on Water Repellency:
Some swimwear, like board shorts, may have a Durable Water Repellent (DWR) coating. This is common in “nylon vs polyester jacket” comparisons. Harsh detergents and frequent washing strip this coating, so if you need water-beading action, use a technical fabric wash designed to protect DWR. For nylon, following nylon waterproof wash dry care helps preserve that water-repellent finish between uses. Proper care keeps the fabric hydrophobic and quick-drying.

Choosing Your Champion: Matching Fabric to Your Swim Life

Your daily swim environment dictates the best fabric choice. Here’s my breakdown from the lab and the pool deck.

Choose Polyester If:

• You are a lap swimmer in a chlorinated pool multiple times a week.
• Your top priority is colorfastness and resisting fade over many seasons.
• You want the absolute quickest drying time, especially for items like board shorts.
• You prefer a slightly crisper, more structured hand feel.

Choose Nylon If:

• You swim mainly in oceans, lakes, or saltwater.
• You prefer a softer, silkier feel against your skin.
• You need superior abrasion resistance for active wear like surf rash guards.
• You prioritize tensile strength and durability for sporty cuts.

Most swimwear is a blend. Nylon or polyester is paired with spandex (elastane) for stretch. A typical 80% nylon / 20% spandex blend offers a soft, strong, and stretchy suit, while an 80% polyester / 20% spandex blend prioritizes chlorine resistance and drying speed. Always check the care label for the blend ratio. Understanding the differences between nylon and polyester can help you choose the best swimwear for your needs.

Are nylon shorts good for swimming? Absolutely. They are durable and strong. Just ensure they have some spandex (usually 10-20%) for comfort and mobility, and follow the care guide to protect that elastane.

For the eco-conscious, recycled options exist for both fibers. Recycled nylon (often from fishing nets) and recycled polyester (from plastic bottles) perform nearly identically to their virgin counterparts, offering a more sustainable choice without sacrificing performance.

While we compare “nylon vs polyester jacket” for rain resistance, swimwear needs are unique: less about waterproofing, more about stretch retention and chemical resistance while wet. Your choice ultimately balances the feel against your skin with the demands of your favorite water.

Final Fabric Insights for Swimwear

Your choice hinges on your main swimming environment: pick polyester for its chlorine resilience in pools, and lean toward nylon for quicker drying in casual or saltwater use. Always pair your choice with a cold, gentle wash and flat air-drying to maintain the fabric’s shape and color intensity for seasons to come.

Extending your swimwear’s life through proper care is a direct step toward reducing textile waste. I encourage you to let this knowledge spark curiosity about all fibers, from why cotton shrinks to how silk dyes, building a more sustainable approach to your entire wardrobe.

Sources and Additional Information

• Sustainable Swim Fabric: Polyester vs. Nylon and our choice
• Understanding the Difference Between Nylon Spandex and Polyester Spandex in Swimwear
• r/arcteryx on Reddit: Can someone break down the differences between polyester and nylon?
• What is the Best Swimsuit Material? – Cheeky Chickadee Store
• Nylon VS Polyester for Swimsuits
• Is Nylon or Polyester Better for Swim Trunks? – Clothing Manufacturer – Modaknits Apparel