Why Mineral Sunscreen — And Why CORE Specifically
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A simple explanation on what's actually inside your SPF. Written for people who want to know what they're putting on their face every morning... and why it matters.
There are only two kinds of sunscreen. Most people don't know the difference.
Every sunscreen in the world falls into one of two camps: mineral (also called physical) or chemical. The distinction isn't marketing — it's about how they interact with UV radiation on a molecular level.
Chemical filters — ingredients like oxybenzone, octinoxate, avobenzone, and butyloctyl salicylate — absorb UV rays, convert them into heat, and release that heat from your skin. To do this, they have to be absorbed into the stratum corneum (the top layer of your skin). Studies published in the Journal of the American Medical Association found measurable levels of these filters in the bloodstream of participants after a single application. The FDA has since requested further safety data on 12 of the most common chemical filters. The EU has restricted several. Hawaii, Key West, and the US Virgin Islands have banned oxybenzone and octinoxate outright because of coral reef damage.
Mineral filters — zinc oxide and titanium dioxide — don't absorb into your skin. They sit on top of it and physically reflect UV rays off, like a mirror. Because they don't enter the bloodstream, they're considered Generally Recognized As Safe and Effective (GRASE) by the FDA — the only two active sunscreen ingredients with that designation.
Why CORE uses zinc oxide only — and what makes our zinc different.
CORE's UV protection comes from 100% zinc oxide. We don't use titanium dioxide, which can leave a heavier, more whitish finish on deeper skin tones. We don't use any chemical filters at all. That means zero absorption, zero hormone-disruption concerns, and zero compromises on broad-spectrum protection.
But "zinc oxide" isn't one ingredient. The particle size, shape, and surface treatment completely change how it performs on the skin:
- Hexagonal platelet technology. Our zinc uses flat, stackable particles instead of the standard spherical ones. Flat particles shield more surface area per gram, which means more protection at a lower concentration — and a dramatically lighter feel.
- Iron oxide neutralization. Zinc has a naturally blue-white refractive index. On its own, it creates that chalky, ashy cast on medium-to-deep skin tones that's historically kept mineral SPF niche. CORE includes a mandatory micro-load of cosmetic-grade iron oxide that neutralizes the blue wavelength — the formula disappears on Fitzpatrick I through VI. Every shade.
- Non-nano particle size. CORE's zinc is formulated above the nanoparticle threshold, which means it cannot penetrate skin or aquatic organisms. This is what makes it reef-safe and body-safe.
Broad-spectrum UVA + UVB. Here's what that actually means.
The sun emits two forms of UV radiation that damage your skin:
- UVB causes sunburn and short-term damage to the outer epidermis. It's what most cheap sunscreens block. SPF numbers refer primarily to UVB protection.
- UVA penetrates deeper into the dermis — where collagen and elastin live. UVA is responsible for an estimated 90% of visible skin aging: fine lines, pigmentation, loss of firmness, sagging. It passes through clouds and window glass. It's the one most people under-protect against.
CORE is tested to a Critical Wavelength ≥ 370 nm — the threshold at which the FDA allows a product to be labeled "broad spectrum." Our SPF30 rating means we block approximately 97% of UVB; the broad-spectrum certification means that protection extends deep into UVA territory.
Why one-step products usually don't work — and why CORE does.
Combining SPF, anti-aging actives, and hydration in a single formula is chemically difficult. Most brands fail in one of three ways:
- Actives that react. Zinc oxide is mildly ionic. When you combine it with copper peptides or vitamin C, those actives can oxidize and lose potency within weeks in the bottle.
- Heavy textures. Mineral SPFs at meaningful concentration tend to sit on the skin like a mask. Without careful emulsification, you either get broad-spectrum protection or a wearable cream — not both.
- Compromises on one pillar. Most "day creams with SPF" max out at SPF 15 and include no real anti-aging work.
CORE solves each:
- The 1% copper peptide (GHK-Cu) is encapsulated in a stabilizing matrix that prevents ion interaction with zinc. The peptide arrives intact, bioavailable, for the full shelf life of the bottle.
- The emulsion is an oil-in-water system with a high water phase and a high-HLB surfactant — which means CORE applies as a quick-break, watery-light cream that absorbs in 30–45 seconds, dry to the touch.
- All three jobs are held to clinical strength. SPF30 broad-spectrum. 1% GHK-Cu (the same concentration used in published dermatological trials). Dual molecular-weight hyaluronic acid. Centella and allantoin for soothing.
The 12-week mark.
Copper peptide GHK-Cu has been studied for its role in collagen synthesis and wound healing for over three decades. Clinical data shows a measurable reduction in fine lines and improvement in skin elasticity within 12 weeks of daily use. That's the timeline CORE is formulated around — and it's why we offer a 60-day money-back guarantee that fully covers the window you need to see if it's working.
Read this far? CORE is what you've been reading about.
100% mineral. Hormone-safe. Invisible on every skin tone. Dermatologist-formulated with published actives. 60-Day Skin Promise.