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Written by OSEA Staff | Last Updated on: May 22, 2026.
You asked, we answered. Since launching Marine Screen SPF 50, we’ve received so many questions from our community about sunscreen and how to use it correctly. So we created this guide to answer some of your most common SPF questions, like what broad spectrum actually means, how much sunscreen to use and whether SPF really belongs in your routine every single day. Let’s get into it.
What Does SPF Mean?
We’re always told to look for sunscreen with SPF, but what does that actually mean? SPF stands for Sun Protection Factor, and it measures how well a sunscreen protects your skin from UVB rays, the ones that primarily penetrate the outer layers of the skin and are responsible for sunburn. But SPF alone doesn’t protect against UVA rays, which contribute to visible signs of premature aging (think fine lines, wrinkles and discoloration). While UVB rays are easier to spot because they cause visible sunburn, UVA rays work more quietly beneath the surface and can contribute to long-term visible skin damage over time. When used as directed, along with other sun protective measures (such as sun-protective clothing), a broad-spectrum sunscreen, like Marine Screen SPF 50, helps protect against both, reducing the risk of visible signs of aging and skin cancer.
What Does the SPF Number Mean?
The number of SPF ranges from SPF 15 to SPF 100, but the amount of protection provided is minimal once you go beyond SPF 50.
- SPF 15: blocks about 93% of UVB rays
- SPF 30: blocks about 97% of UVB rays
- SPF 50: blocks about 98% of UVB rays
So which SPF level should you choose?? The Skin Cancer Foundation recommends using a broad spectrum sunscreen with at least SPF 30 for days spent indoors and SPF 50 for outdoor activities.
Do You Need to Wear SPF Indoors?
If there’s one thing dermatologists unanimously agree on, it’s that SPF is the most important step in your routine, every single day. All of the benefits of your favorite skincare products (hello Hyaluronic Sea Serum) can be diminished by damaging and aging UVA/UVB rays. UV damage happens year-round. It happens on cloudy days. It happens through windows. It even happens in winter. So applying SPF to your face and neck daily is necessary, whatever the season.
The key is finding one you'll actually want to wear. You want something that protects and plays nicely with everything else in your routine. Our Marine Screen Mineral SPF 50 uses non-nano zinc oxide to shield skin from UVA/UVB rays with clean, lightweight, hydrating protection.
When and How to Apply Sunscreen
Sunscreen is always the final step in your skincare routine, after moisturizer but before makeup (if you wear it). Apply at least 15 minutes before sun exposure and reapply every two hours for full SPF protection.
The amount matters. Your face needs 2mg/cm² – enough to coat the entire surface area of exposed skin, which is roughly half a teaspoon, or two-finger lengths of sunscreen. Anything less and you’re not getting the protection on the label. It might seem like a lot, but trust us, your future skin will thank you.
Sunscreen vs. Moisturizer: Which Comes First?
As we mentioned above, sunscreen comes after moisturizer, always. We don’t recommend mixing sunscreen with a moisturizer, as it will dilute and change the efficacy of the sun protection. Our Marine Screen wears beautifully over moisturizer and under makeup.
Do Mineral Sunscreens Leave a White Cast?
While there have been advancements in SPF formulation, mineral sunscreen can never be 100% invisible. Mineral filters like zinc oxide and titanium dioxide are naturally white powders that sit on top of the skin to form a physical barrier, making it impossible for mineral SPF to be completely invisible across every skin tone.
Our Marine Screen SPF 50 uses non-nano zinc oxide and was formulated to be lightweight and blendable to help minimize the look of white cast. Pro tip: It blends best when warmed and pressed into well-hydrated skin. We tested the formula across the Fitzpatrick skin tone scale to help ensure it blends as seamlessly as possible.
What Is the Best Way to Remove SPF?
Cleansing is essential on any day, but even more so when you’ve been wearing sunscreen. Start with a cleansing oil like our Ocean Wave Cleanser to effortlessly melt away oil-based impurities like makeup, excess sebum and daily buildup. Follow with a water-based cleanser for a deeper cleanse that is appropriate for your skin type. Our pH-balanced Ocean Cleanser removes surface impurities and excess oils while gently exfoliating with lactic acid for a clear-looking, radiant complexion that's perfectly prepped for the rest of your routine.
In the end, the best SPF is the one you'll actually use. Every day. Rain or shine. If it pills, irritates or feels greasy, you won't want to wear it. If it feels like skincare, you will.
That's what we designed our Marine Screen SPF 50 to be: clean, lightweight, hydrating protection, made for your every day. For the sun you live in. Because SPF should be the least complicated part of your routine.
Ready to sea the difference™? Discover Marine Screen SPF 50 today.