When we started making Shade, the concept was simple: make a mineral sunscreen that sensitive skin can actually use, with as few natural ingredients as possible - and still be genuinely protective. We landed on just four ingredients. Pushing SPF sky-high with only four would make a very thick, chalky paste that most people would apply too thinly, slashing the real-world protection - exactly what we were trying to avoid. Under typical use, consumers often apply ¼–½ of the lab-tested amount (2 mg/cm²), which can halve the effective SPF. 

Below is why we deliberately offer SPF25 - and not 50, 70 or 100.

Four problems with high SPF

1) Poor UV balance (UVA vs. UVB).
SPF measures UVB (sunburn) protection; it says little about UVA, which drives deeper damage like photoaging, immune suppression and contributes to skin cancer risk. The U.S. “broad-spectrum” test relies on a critical wavelength cut-off and doesn’t guarantee a strong UVA-PF/SPF ratio. In 2019 the FDA proposed tying higher SPF to higher UVA protection because current rules can allow high-SPF products with relatively weak UVA shielding. Independent lab testing has also found some sunscreens deliver even less UVA protection than labels imply.

UVA’s harms are well documented: it penetrates more deeply, generates reactive oxygen species, and suppresses cutaneous immunity. 

2) High SPF can change behaviour.
People feel “safer,” stay out longer, and still get sunburned - while taking on more UVA dose. Classic field studies by Philippe Autier and colleagues showed higher-SPF users often extend sun exposure; later reviews influenced FDA rulemaking. 

3) Diminishing returns.
SPF isn’t linear: properly applied SPF25 blocks ~96% UVB; SPF 50 blocks ~98% UVB; SPF 100 ~99%. That single extra percent can be wiped out by under-application or missed spots, while still not fixing UVA balance. Dermatology guidance focuses on broad-spectrum products and correct use, not ever-higher numbers. 

4) More actives, more exposure.
Very high SPF formulas typically require higher loads of UV filters. FDA-sponsored trials show several common organic (chemical) filters are systemically absorbed at levels that trigger the need for additional safety data; the clinical significance is still being studied. Mineral filters (zinc oxide, titanium dioxide) are not the ones implicated here. 

Why Shade is SPF 25

• Balanced, wearable protection.
  Our non-nano zinc-based formula with four natural ingredients aims for a smooth film people will actually apply at a realistic thickness - because how you use sunscreen matters as much as what’s on the label. Real-world use below 2 mg/cm² can slash delivered SPF; designing for pleasant, even application helps keep protection closer to the claim.
• Support natural resilience (safely)
  Regular, sub-erythemal UV exposure (i.e., not burning) can trigger adaptive responses - increased melanin and stratum corneum thickening - which provide additional photoprotection over time. This is not a license to bake; it’s an explanation for why moderate SPF, clothing and shade together can be a smart, sustainable regimen. 
• Vitamin D, without the burn.
  UVB initiates vitamin D synthesis in skin via 7-dehydrocholesterol → previtamin D₃ → vitamin D₃. Well-designed trials and expert consensus indicate that proper sunscreen use does not necessarily compromise vitamin D status in healthy people, especially with balanced UVA/UVB protection and typical outdoor behaviour. 

Our take on the numbers game

Regulators have long debated caps on labelled SPF because benefits above 50 are uncertain. The FDA’s 2011 proposal would have limited labels to “50+”; its 2019 update proposed a top label of “60+” while strengthening UVA requirements - a direction we endorse. Whatever the cap, broad-spectrum performance and correct application are the wins that matter. 

Bottom line: Shade’s SPF 25 is intentional. It’s about balanced UV protection and minimal, natural ingredients - protection you’ll actually use generously and reapply.