How Does SPF Work?

How Does SPF Work? And Why We Chose Zinc and SPF 30

When we set out to create a sunscreen at Scence, we didn’t just want any SPF. We wanted something that felt good on your skin, aligned with our values, and genuinely protected you and the planet. But to explain why we chose zinc and SPF 30, it helps to start with the basics…

What does SPF actually mean?

SPF stands for Sun Protection Factor, and it measures how well a sunscreen protects you from UVB rays – the ones responsible for sunburn.

• SPF 15 blocks about 93% of UVB rays
• SPF 30 blocks about 97%
• SPF 50 blocks about 98%

That jump from SPF 30 to SPF 50 sounds big, but in reality, it’s only a tiny increase in protection. No sunscreen blocks 100%.

So the question becomes: What’s enough protection, without overcomplicating things or compromising the formula?

For us, the answer was SPF 30 – the sweet spot of high protection + everyday usability.

How sunscreen protects your skin

There are two main types of sunscreen:

1. Chemical sunscreens

These absorb UV rays and convert them into heat inside your skin.

2. Mineral sunscreens (like ours)

These sit on top of your skin and reflect UV rays away, acting like a physical shield

At Scence, we chose the second option – and specifically one ingredient…

Why we chose zinc oxide

Zinc oxide is a naturally occurring mineral, and it’s one of the most effective and trusted UV filters available. Here’s why we love it:

Broad-spectrum protection

Zinc protects against both UVA (ageing) and UVB (burning) rays in one ingredient

Works instantly

Unlike chemical sunscreens, zinc starts protecting the moment you apply it

Gentle on skin

It’s non-irritating and suitable for sensitive skin, even helping calm inflammation

Stays stable in the sun

Zinc doesn’t break down under UV light, so the protection you apply is the protection you get

Better for the environment

We use non-nano zinc, which sits on the skin and is considered safer for marine life than many chemical filters

How often should you apply SPF 30?

This is the part that’s often overlooked – but it makes all the difference. SPF isn’t a one-and-done step. To stay protected, SPF 30 should be:

• Applied generously in the morning as the final step in your routine
• Reapplied every 2 hours when you’re outdoors
• Reapplied after swimming, sweating, or towel drying

Even the best sunscreen naturally wears off throughout the day – through movement, touch, and exposure and most of us apply less than we think we do. That means the real protection we get is often lower than the number on the label – which is another reason we chose a reliable, everyday SPF 30 that’s easy to reapply.

Because sunscreen only works if it’s used, and used properly.

Why SPF 30 (not higher)?

We tested and tested  and came back to SPF 30 again and again.

• It already blocks ~97% of UVB rays
• Higher SPFs only add marginal extra protection
• They often require heavier formulas or more complex ingredients
• And most importantly – people are more likely to use SPF 30 properly and regularly

And consistency is everything. A perfectly applied SPF 30 beats a rarely used SPF 50 every time.

The Scence approach

Our sunscreen is built around a few simple principles:

• Zinc-based, mineral protection
• SPF 30 for everyday, real-life use
• Plastic-free packaging
• Gentle, family-friendly formulation

We created something that works with your skin, not against it and that you’ll actually want to use. Because the best sunscreen isn’t the highest number on the label… it’s the one you’ll use every day.