Curious as to how two products with the same amount of active sunscreen ingredients can have different SPF and PPD ratings?
The protection provided by sunscreen chemicals are modified by the other ingredients in a sunscreen formulation as well.
Waxes reduce the recovery time of a sunscreen product. This means that the product hardens up more quickly than without the wax, which creates a more even application. Products with a long recovery time can flow into wrinkles of the skin, creating an uneven coverage.
Film formers, like polymers, are also able to create a more even distribution of sunscreen on the skin.
There’s also new additives that modify the way that UV light interacts with the sunscreen chemicals.
Synthetic hollow spheres have been created that help scatter and “bounce” light. The UV light has a longer path to travel before reaching the surface of the skin where the sunscreen chemicals are. The longer the path length, the more absorption a sunscreen chemical can provide. The incorporation of these light scattering spheres can boost protection by 50% across the full UV spectrum!
This means that companies using this technology can reduce the amount of sunscreens to achieve an SPF, or enhance their product’s protection beyond the ingredient limit set by regulatory bodies.
Look for the ingredient “Styrene/Acrylates Copolymer” on the label (but contact and ask the company if they’re using this technology to be sure, as it can also just be used as a regular film former). Biotherm has used this technology in their Brume Solaire Lactée SPF 50 Spray. Heliocare also uses it in their Extreme SPF 50 Gel Sunscreen.