Does UPF Clothing Lose Its Effectiveness Over Time?

The short of it is-- yes, UPF clothing can become less effective over time, but how quickly that happens depends on the fabric, construction, wear, and care. Stretching, repeated laundering, prolonged exposure to sunlight, and general wear can change a fabric's ability to block UV radiation. The good news is that standardized testing can account for some of these changes, so a UPF rating isn't necessarily based only on a brand-new piece of fabric.

What Makes UPF Clothing Lose Effectiveness?

UPF is a measurement of how much ultraviolet radiation passes through a fabric. As a textile changes, so can its UV protection.

One of the biggest factors is stretching. When fabric stretches, the spaces between its fibers can become larger, allowing more UV radiation through. The Skin Cancer Foundation notes that clothing can lose some protective ability when it becomes stretched or wet.

Washing and everyday wear can also affect a textile over time. Changes in the fabric's structure, finishes, color, or density can influence how much UV radiation passes through.

This doesn't mean that your UPF shirt suddenly stops working after a certain number of washes. There isn't a universal expiration date for UPF clothing. How long it remains highly protective depends on the particular fabric and how the garment is used and cared for.

How Is UPF Durability Tested?

This is where UPF testing gets interesting.

ASTM D6544 provides a standardized practice for preparing UV-protective textiles for testing. It exposes fabrics to conditions including laundering, simulated sunlight, and chlorinated pool water to simulate approximately two years of seasonal use. The fabric can then be tested for its remaining UV protection using AATCC TM183.

In other words, testing can look beyond the fabric when it's brand new. The goal is to understand how its UV protection performs after conditions that mimic real-world use.

ASTM describes UV resistance as dynamic, meaning it can change as a textile is exposed to use and environmental conditions.

Does Washing UPF Clothing Reduce Its Protection?

It can, but the answer depends on the fabric and how it achieves its UPF rating.

Some UV-protective fabrics rely on the inherent construction of the textile, while others use finishes or treatments. Their durability can therefore behave differently with repeated washing.

This is one reason following the garment's care instructions matters. Avoiding unnecessary heat, harsh chemicals, excessive stretching, and other forms of fabric stress can help preserve the garment's original properties. Before you purchase, look to see if the UPF is through chemical washes or inherent. 

And if a UPF garment becomes noticeably stretched, thin, damaged, or worn, it's reasonable to assume that its protective performance may have changed.

What About UPF 50+?

UPF 50+ is the highest classification in the UPF rating system, but the label isn't a guarantee that a garment will provide exactly the same protection forever.

The testing and labeling standards recognize this. ASTM D6603 states that the labeled UPF should reflect the lower protection value expected during consumer use over a two-year period in the applicable testing framework.

That's an important distinction: UPF 50+ describes tested performance under specified conditions; it isn't an expiration date or a lifetime guarantee.

How Can You Make Your UPF Clothing Last Longer?

The best approach is simple: treat UPF clothing like any other well-made garment. In fact, make sure you choose high quality UPF. At Some Sun, we make our UPF out of premium materials.

Follow the care label, avoid unnecessary stretching, and replace clothing when the fabric becomes significantly worn, damaged, or stretched out.

It's also worth remembering that UPF protects only the skin covered by the garment. The Skin Cancer Foundation recommends combining protective clothing with other sun-protection measures, particularly for areas left exposed.

The Bottom Line

UPF clothing can lose some UV-protection performance as the fabric ages, but there is no universal point at which UPF clothing “stops working.” Fabric construction, stretching, laundering, sunlight, moisture, and wear all play a role.

When buying UPF clothing, look for a specific UPF rating and information about how the fabric was tested. And when you own it, caring for the garment properly is one of the simplest ways to preserve its performance.

At Some Sun, we believe sun protection should be something you can incorporate naturally into the way you dress—without adding another complicated step to your routine. See our blog about why summer fabrics might not be protecting you (which is why we make cotton-feel UPF).

The best UPF garment is one you'll actually wear, care for, and reach for again.

Sources

• ASTM International, D6544: Standard Practice for Preparation of Textiles Prior to Ultraviolet (UV) Transmission Testing
• ASTM International, D6603: Standard Specification for Labeling of UV-Protective Textiles
• AATCC, TM183: Transmittance or Blocking of Erythemally Weighted Ultraviolet Radiation through Fabrics
• Skin Cancer Foundation, Sun Protective Clothing