Our sunscreen is extremely Photo Stable.
What does this mean? It means that there is minimal discernable drop in SPF in testing from Pre Irradiation to Post Irradiation. In other words when you are out in the Sun the SPF and UVA protection will continue to be the same as what it tested at. Our UVASPF testing showed negligible drop in performance between pre and post irradiation indicating that it was highly photo- stable. Photo – stable sunscreens also generate minimal Free – Radicals.
EWG in “Methodology for Assessing Sunscreens” rates Zinc Oxide as completely photo-stable with no degradation.
Many sunscreen ingredients, especially the chemical UV absorbers experience a significant drop in performance when subjected to UV radiation. Coupled with this the energy absorbed from the sun by these chemical UV absorbers that causes the performance to drop actually incites Free Radical generation. To get around this, some formulators have had to add other chemical ingredients to stabilize the active UV filter.