Why We Don't Recommend DIY Sunscreen (and What Brands Need to Know)

This might be an unusual post for an ingredient store. We love DIY. We'll happily help you make a serum, a cleanser or a body butter. But there's one product we'll always talk you out of making at home: sunscreen. Here's why.

The Pinterest experiment

In 2019, researchers analysed homemade sunscreen recipes shared on Pinterest. Their findings were alarming: 95% of the pins portrayed homemade sunscreen as effective, yet 68% of the recipes offered insufficient UV protection. Claimed SPFs ranged from 2 to 50, and none of the pins offered any proof (Nationwide Children's Hospital; study: Merten et al., Health Communication).

Why SPF can't be "mixed in"

• SPF is measured, not calculated. You can't add up ingredient percentages and get an SPF number. It has to be tested on human skin using a standard method such as ISO 24444.
• Even dispersion is everything. Mineral filters like zinc oxide must be spread perfectly evenly through a formula. Clumps leave gaps, and gaps mean a product may not reach its SPF (Cosmetics & Toiletries). Home stirring just can't guarantee that, as PBS NewsHour explains (PBS NewsHour).
• UVA matters too. SPF mostly reflects UVB (burning). Broad-spectrum protection against UVA (ageing) needs its own testing.
• Batch to batch varies. Without testing, one jar can protect very differently from the next.

It's a regulated product, almost everywhere

• United States: sunscreens are regulated as over-the-counter drugs, and all sunscreens must be tested to determine their SPF (FDA).
• European Union: only UV filters listed in Annex VI of the Cosmetics Regulation may be used, at their permitted concentrations (Regulation (EC) No 1223/2009).
• India and other markets have their own standards and approved filter lists. Always check where you'll sell.

What about "natural SPF" oils?

You'll often see plant oils described as having a "natural SPF". Some oils absorb a little UV, but nowhere near enough, and not reliably enough, to protect you. Please don't use any oil as your sunscreen.

So why do we sell UV filters?

For professional formulators and brands working with proper testing. If that's you, here's the responsible route:

1. Choose approved filters for your target market, for example Zinc Oxide (Non-Nano, Coated), Titanium Dioxide (Non-Nano, Coated), or modern organic filters like Bemotrizinol and Tris-Biphenyl Triazine where permitted. Each dictionary entry flags that use levels follow your destination market's maximum.
2. Work with an experienced sun-care chemist on dispersion, film formation and photostability.
3. Test it properly: in-vivo SPF, UVA protection, water resistance if you claim it, stability and preservative efficacy.
4. Register and label it according to local rules.

What DIYers can do instead

Buy a well-tested commercial sunscreen you love wearing, and channel your creativity into the products around it: an antioxidant serum to wear underneath (see our vitamin C guide), or a soothing after-sun gel with Aloe Vera and Panthenol.

Brands can browse UV Filters and Sunscreen Ingredients. Everyone else: wear your (tested) sunscreen, and let us help with everything else.

This article is educational and not medical or regulatory advice.