All things SPF
August 06, 2026
Mineral Sunscreen That Isn't Greasy
Greasy is not a zinc problem. It is an oil problem. Swellies has no oil and no water, so there is nothing...
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August 06, 2026
Zinc Oxide Absorbs UV Light. It Does Not Absorb Into You.
Zinc oxide absorbs UV below about 375nm and scatters the rest. The mechanism, what SPF it can reach, and what particle size...
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August 04, 2026
What Is Butyloctyl Salicylate? The UV Absorber Hiding in Your Sunscreen’s Fine Print
Butyloctyl salicylate absorbs UV and boosts SPF, but it is not an FDA-approved filter, so it sits in the inactive list instead...
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August 03, 2026
Does Sunscreen Cause Skin Cancer? Of course not.
Melanoma diagnoses rose for fifty years while deaths stayed flat. That gap is the whole story, and it points at how we...
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July 30, 2026
The FDA Just Approved Bemotrizinol. Here's Why Swellies Is Still Mineral-Only.
In June 2026 the FDA authorized bemotrizinol, the first new sunscreen filter in about twenty years. It is good news for the...
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July 26, 2026
Why Sunscreen Goes White Under Makeup (and How to Stop It)
A gray cast through your foundation and little rolls of pilling product are two separate problems. Here is the mechanism behind each,...
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July 25, 2026
The Real Dangers of DIY Zinc Oxide Sunscreen
A homemade formula with 25% zinc oxide measured SPF 7 at an FDA approved lab. The ingredients were not the problem. Dispersion...
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July 24, 2026
The Minimal Sunscreen That Feels Elegant, Not Like Cream Cheese on Your Face
Most people quit mineral sunscreen over the feel, not the protection. Here is why it usually feels heavy, how coco caprylate/caprate makes...
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July 20, 2026
Sunscreen Flashback: Why You Look White in Flash Photos
Mineral sunscreen shows up white under a camera flash because zinc oxide scatters visible light. Here is the mechanism, why the usual...
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