There’s a common assumption that sunscreen works as a kind of guarantee. Apply it. Reapply it. You’ll be fine. It’s an understandable way to think about it - but it isn’t how sun protection actually works.
At any UV level, sunscreen doesn’t stop exposure. It reduces it. A proportion of UV still reaches the skin, and that exposure continues to build for as long as you’re in the sun. In the case of Shade, SPF25 allows 4% of photons that hit the skin to penetrate, the other 96% are reflected and scattered away. Reapplying helps maintain protection, but it doesn’t reset that exposure back to zero.
That principle doesn’t change. What changes is how quickly your skin reaches its limit.
In lower UV, you may have more time before that happens. In higher UV, that window becomes much shorter. The margin for error shrinks, and the consequences show up faster.
This is why people are often caught off guard on holiday, or in unfamiliar conditions. Not because sunscreen “isn’t working”, but because the level of exposure is very different to what their skin is used to.
Most of us spend much of the year indoors. Even in summer, exposure tends to be gradual and inconsistent. As a result, skin isn’t particularly well adapted to sudden, sustained UV - especially at higher levels. When that exposure increases quickly, the skin can reach its tolerance far sooner than expected. And it’s not always obvious when that’s happening.
It's not about temperature
UV doesn’t behave in the way people expect. It isn’t tied neatly to temperature or how bright the sun feels. It passes through cloud. It reflects off water. It peaks in the middle of the day, when the sun is highest overhead. So it’s entirely possible to build up significant exposure without it feeling especially intense in the moment. This is where expectations around sunscreen start to matter.
SPF is often interpreted as a level of protection that allows you to stay in the sun for as long as you like, as long as you keep reapplying. But in reality, even very high SPF products allow a small amount of UV to pass through. Over time, that adds up. In higher UV, it adds up quickly. And that’s true of all sunscreens.
There isn’t a formulation that blocks 100% of UV, or that prevents exposure from accumulating. What sunscreen does is reduce the rate at which that exposure builds - which is useful, but not absolute.
A simple way to think about it is that sunscreen gives you more margin. It doesn’t remove the need to make decisions about your exposure.
It’s a bit like wearing a life jacket. It improves your chances, but it doesn’t make you immune to the conditions around you. If those conditions become more extreme, your overall risk still increases.
Sun exposure works in much the same way. It’s shaped by a combination of factors - the UV level, the time of day, how long you’re in direct sun, your environment, and your individual sensitivity. Medication, hormonal changes, and general skin condition can all influence how quickly your skin reacts, sometimes in ways that aren’t immediately obvious.
Mineral sunscreens, in particular, work by forming a physical layer on the surface of the skin. That layer reflects and diffuses UV, rather than absorbing it within the skin. It’s an approach that aligns with how we formulate Shade - but it also means that protection is directly influenced by what happens on the skin itself.
Friction, movement, time in water, lying on a towel, even normal daily activity can gradually reduce that layer. Reapplication helps maintain coverage, but it doesn’t undo exposure that has already taken place. Which is why, particularly in higher UV, how the product is used - and how overall exposure is managed - becomes so important.
Ultimately, sunscreen is one part of protection. It doesn’t replace judgement.
Protecting your skin comes down to understanding the conditions you’re in, how long you’re exposed for, and how your skin is responding in real time.
Because your risk isn’t fixed.
It changes depending on the day, the location, your environment, and your individual sensitivity.
At Shade, we’ve always tried to reflect that. Not by presenting sunscreen as a standalone solution, but by being clear about how it works, and where its limits are. Because protecting your skin isn’t passive - it requires awareness, adjustment, and, at times, restraint.
If you’ve ever burned despite “frequently reapplying”, it generally means one, two or all of three things:
1. the conditions were stronger than expected;
2. your exposure lasted longer than your skin could tolerate, and those limits were reached;
3. the limitations or usage recommendations of the product were misunderstood, not heeded, or simply not researched in the first place.
Once you understand these facts, you’re in a much better position to manage your exposure, and prevent the burn ever happening to you. Check the UV index, and be prepared.
The brutal truth is:
Sunscreen can only support YOU - the ultimate responsibility comes down to your own decision-making.