Does UPF wash out of clothing?

Does the faded rash guard in your laundry basket still block UV rays? Ultraviolet protection factor (UPF) washes out of clothing over time, but the fabric, construction, care practices, and manufacturing determine how quickly UPF fades. 

You play a big role in the longevity of your UPF clothing. We’ll examine the science of UPF clothing. You'll also learn how to preserve sun protection, recognize when it's declining, and make informed choices about replacement.

SwimZip is your source for dermatologist-certified UPF 50+ swimwear for men, women, and children of all ages.

All clothing blocks some UV rays

Every piece of clothing you own already provides some sun protection. A typical cotton t-shirt provides UPF 5–10, blocking 83–90% of UV radiation. For daily life, regular clothing protects you just fine.

But extended sun exposure calls for higher protection. Swimming at the beach, hiking mountain trails, spending hours at the playground, or participating in outdoor sports that subject you to hours of intense UV rays.

Sun-protective swimwear, hiking apparel, outdoor athletic wear, and other technical clothing carry ratings that tell you how much UV radiation they block.

How fabric blocks UV radiation

Fabrics block UV through two mechanisms, which determine whether your garment's protection survives constant washing or gradually disappears down the drain.

Structural UV protection

Inherent or structural UV protection comes from a garment’s material properties and construction methods. Nothing washes away because the fabric's physical characteristics provide protection.

Four factors create this resilient defense:

1. Fabric: Synthetic fibers, like polyester and nylon, absorb UV radiation better than natural fibers. Unbleached cotton only blocks about 50% of UV rays, while polyester blocks over 90%, even without special treatments.
2. Weave density: It controls how much light passes through the fabric. Hold a loosely woven cotton t-shirt up to a window and you'll see daylight filtering through the gaps between threads. Tightly woven fabric eliminates gaps.
3. Color intensity: Dark, rich colors absorb more UV radiation than pale or bleached fabrics. A navy blue shirt blocks more UV than the same shirt in white or pastel yellow. The dye molecules themselves absorb UV rays before they reach your skin. This is true whether you're wearing cotton or synthetic fabrics.
4. Material thickness: Thick fabrics force UV rays to travel through more material before reaching the skin. This explains why a heavy denim jacket provides better protection than a lightweight linen shirt, even though both use natural fibers.

Garments built with inherent protection maintain their ratings until the fabric structure physically degrades. While this form of UPF protection doesn’t wash off, thinning, permanent stretching, or holes reduce protection.

Applied UV protection

Chemical treatments also increase UV protection and UPF rating. They work, but they sit on the fabric surface rather than fusing with the fiber.

Manufacturers apply chemicals through sprays and baths, but neither application method creates protection that lasts longer than structural UPF.

Surface treatments wash away gradually with each laundering cycle.

• Detergents lift the chemicals off fibers.
• Mechanical washing physically scrubs them away.
• Heat from water and dryers accelerates chemical breakdown.

These treatments also degrade from environmental exposure. Chlorine, saltwater, and ironically, UV radiation from sunlight attack the protective compounds.

Treatment quality varies between manufacturers. Budget brands might use simple spray applications that wash away after 20–30 cycles. Premium brands engineer treatments that chemically bond to fibers and survive 100–500 washes.

High-quality UPF clothing combines both approaches. Manufacturers start with UV-resistant synthetic fabrics sewn in tight weaves, then add chemical treatments for extra protection. When the applied treatment eventually degrades, the fabric still provides baseline protection from its structural properties.

The research on UPF durability

Washing degrades applied treatments

A 2023 study published in a peer-reviewed textile journal examined how routine laundering impacts UPF protection. The findings confirm that textiles treated with UV-blocking finishes lose effectiveness over repeated wash cycles. The protective finish gradually washes away, breaks down from detergent exposure, or degrades from mechanical washing action.

Manufacturer claims vary

According to the Cleveland Clinic, a well-made UPF garment typically lasts 2–3 years with regular use and proper care. Industry testing reveals dramatic variation in durability claims. Some manufacturers test garments through 30–50 washes, while others engineer fabrics retaining protection through 100–500 washes.

But just because your UPF clothing shows no visible wear doesn't mean it provides full protection. UV-blocking chemicals can degrade while the fabric looks fine. Only laboratory testing provides precise UPF measurements. For everyday assessment, rely on visual warning signs, manufacturer wash-count guarantees, and garment age (explained below).

What degrades UPF protection (and how to preserve it)?

Multiple factors degrade UPF clothing over time. By understanding these stressors and following smart care practices, you can get the most out of your UPF clothing.

Washing and heat damage

Washing practices cause the most frequent and preventable damage to UPF clothing.

• Hot water breaks down UV-blocking treatments by accelerating chemical reactions that degrade the protective compounds.
• Harsh detergents with optical brighteners, enzymes, or heavy alkaline content attack UV-blocking treatments. Optical brighteners absorb UV light and re-emit it as visible light, which interferes with UV-blocking compounds. Enzyme-based detergents break down proteins and other organic compounds, which include some UV treatments.
• Mechanical agitation physically scrubs UV-blocking compounds off fabric surfaces during the wash cycle. 
• Dryer heat compounds the damage by breaking down UV-blocking chemicals, while tumbling adds mechanical stress.

Washing best practices

• Use cold or lukewarm water (below 85°F). Detergents effectively clean in cold water while preserving UV protection.
• Choose mild, fragrance-free detergents without optical brighteners. Look for formulas designed for technical fabrics or delicate items.
• Skip fabric softeners, and use vinegar in the rinse cycle instead; one-quarter cup softens without the coating.
• Select delicate or gentle cycles that minimize mechanical agitation.
• Turn garments inside out. This reduces surface abrasion during washing, protecting UV treatments on the exterior.
• Use mesh laundry bags. Place garments in mesh bags to prevent tangling, reduce friction, and minimize stretching.

Chlorine and saltwater exposure

Pool chlorine and ocean salt water attack fabric fibers and UV treatments. Chlorine oxidizes fibers, weakening fabric structure and degrading protective compounds. Salt crystals left after ocean swimming create tiny abrasive particles that physically wear fabric.

This is why sun-protective swimwear uses chlorine-resistant fabrics that withstand pool chemicals.

Post-swim garment care

• Immediately rinse chlorine and salt water from fabric using shower water at the pool or beach, or rinse at home within an hour.
• For single-use situations, hand-wash swimwear in lukewarm water with gentle soap to remove sunscreen residue and body oils.
• Squeeze excess water out by pressing the garment between your hands or rolling it in a towel.
• Rotate multiple garments to let each one fully dry between uses.

Physical wear and stretching

Physical wear from normal use gradually degrades UV protection even when you wash garments properly. Fabric thinning occurs wherever garments experience repeated friction. For example, elbows on long-sleeve rash guards, knees on swim leggings, and shirt shoulders under backpack straps degrade quickest.

Stretching opens gaps between fibers in the fabric weave at stress points. Weak points include waistbands, necklines, and other areas where fabric stretches over your body. Once stretched, fabric rarely returns completely to its original tight weave. Pilling and surface damage from abrasion remove material from fabric surfaces, degrading the fabric and any UPF treatment.

Physical wear is an inevitable part of using your UPF clothing. The best way to minimize unnecessary wear is to get the right size, since overly tight fits stretch and stress the fabric.

Drying and storage practices

Air drying is the gentlest treatment for UPF clothing. Hang garments in shaded, well-ventilated areas away from direct sunlight. This prevents additional UV exposure while the fabric dries. Don't lay wet swimwear or hiking gear in direct sunlight.

If you must use a dryer, select the lowest heat setting and remove items while slightly damp, and finish by airdrying. Never use high heat settings.

If you’re storing your UPF clothing for the season, follow these tips to keep it from unnecessary damage:

• Wash all garments thoroughly.
• Dry completely.
• Store in climate-controlled spaces rather than attics, basements, or garages.
• Use breathable storage, like cotton bags, cardboard boxes, or open shelves.
• Hang garments when space allows.

When to replace UPF clothing

All UPF clothing eventually needs replacement. Inspect UPF clothing regularly for these signs that it’s time to replace:

• Fabric thinning: Hold garments up to bright light. If you see light glowing through areas that should be opaque, the fabric has thinned enough to reduce UV protection.
• Color fading: When colors fade from vibrant to pale, UV-blocking compounds have likely degraded too.
• Persistent stretching: Fabric that no longer returns to its original shape has lost structural integrity, creating gaps for UV penetration.
• Pilling and surface roughness: Run your hand over fabric surfaces. Smooth material maintains better protection than rough, damaged surfaces.
• Holes or tears: Even tiny holes compromise protection.
• Elasticity loss: Swimwear that sags or bags has lost the structure that maintains UV protection.

How to choose long-lasting UPF clothing

Care can extend the lifespan of UPF clothing, but you should also look for clothing that is made to last. Check for these durability and effectiveness indicators when shopping for UPF garments:

• Third-party certification: For example, SwimZip swimwear holds the Skin Cancer Foundation Seal of Recommendation. This guarantees the quality and UV protection of our UPF swimwear.
• Wash-count guarantees: Some manufacturers specify how many washings fabrics can withstand while maintaining UPF ratings. Garments rated for 100+ washes are above average.
• Fabric composition: Stick with synthetics (polyester, nylon, spandex). These materials provide better inherent UV protection than natural fabrics.
• Construction quality: Examine seam strength, stitching density, and fabric weight. Heavier-weight fabrics generally provide better mechanical protection.

Sun protection is important for everyone, but people with photosensitivity conditions, those recovering from skin cancer treatment, or anyone taking medications that increase UV sensitivity need maximum sun protection. Shop for UPF 50+ clothing that blocks 98% of UV rays.

SwimZip: Sun protection that lasts

SwimZip offers UPF 50+ sun-protective swimwear backed by rigorous testing in sizes and styles the whole family will enjoy. Every garment carries the Skin Cancer Foundation Seal of Recommendation, so your family can safely enjoy the sun, season after season.

Here’s how we’ve built superior UV protection into our entire swimwear line:

• Chlorine-resistant fabrics
• Durable construction
• Full-coverage designs

🏊 Explore our swimwear collection to find sun protection that looks good and doesn’t wash off.

UPF clothing FAQ

How can you tell if clothing has UPF protection?

Check the garment's label or hang tag for a UPF rating (typically UPF 15, 30, or 50+). Manufacturers of tested UPF clothing display ratings along with care instructions. You can also look for third-party certifications.

Can you add UPF to regular clothing?

Some laundry additives claim to add UV protection to regular fabrics during washing by depositing UV-blocking compounds onto fibers, but the protection level is typically lower than UPF-rated clothing. Purpose-built sun-protective clothing provides more reliable protection.

Can you tan through UPF clothing?

Minimal tanning can occur through UPF 50+ fabric since 2% of UV rays still penetrate. This tiny amount of UV exposure is generally insufficient to produce noticeable tanning during reasonable wear periods. If fabric becomes stretched, worn, or degraded, more UV penetrates and tanning can occur.

😎 Learn how to get rid of a sun tan.

Do you need sunscreen under UPF clothing?

You don’t need to wear sunscreen under properly fitted, intact UPF 50+ clothing. The fabric provides physical sun protection that doesn't wear off like sunscreen. 

You should still apply sunscreen to exposed skin not covered by clothing.

⛱️ Read our sun protection tips guide for more information.

Is UPF clothing better than sunscreen?

Combine UPF clothing and sunscreen for optimal protection. UPF clothing provides reliable, continuous protection that doesn't wear off, sweat off, or need reapplication. Apply sunscreen to exposed areas that clothing can't cover, like the face, hands, ears, and neck.

For extended sun exposure, especially water activities, UPF swimwear provides superior protection than sunscreen since it can't wash off or wear thin from towel drying.

🔎 Learn more about the differences between UPF and SPF.

Further reading

What is a rash guard?

What is a sunsuit?

Best rash guards for sun protection

Kids’ sun safety tips

What is the UV index?

How to wash swimsuits

What are rash guards made of?

References

"The Impact of Routine Laundering on Ultraviolet Protection Provided by Fabrics." National Center for Biotechnology Information, 2023, https://pmc.ncbi.nlm.nih.gov/articles/PMC10440054/.

"Does Sun-Protective Clothing Actually Work?" Cleveland Clinic, https://health.clevelandclinic.org/does-sun-protection-clothing-actually-work.

"7 Things to Know About UPF, Sun Protection and Clothing." MD Anderson Cancer Center, https://www.mdanderson.org/cancerwise/7-things-to-know-about-upf--sun-protection-and-clothing.h00-159698334.html.

"How to Choose Sun Protection UPF Clothing." REI Co-op, https://www.rei.com/learn/expert-advice/sun-protection.html.