Sun filters fall into two categories - physical and chemical.
These work by reflecting UV light away from the skin - they are like a physical barrier between the skin and the light. Examples include Titanium dioxide and Zinc oxide.
These work by undergoing a chemical reaction in the presence of UV light. As part of this reaction, the energy of the UV light is converted into a different form, usually heat. As a result of this reaction the structure of the UV filter changes and it gradually loses its protective properties. This is why we recommend re-applying sun lotions every 2 to 3 hours to maintain protection.
As a result of their activity, some UV filters can release free-radicals. Some filters are more likely to cause free-radical generation than others – the grade of Titanium dioxide that we use, and the Isoamyl p-methoxycinnamate derived from cinnamic acid have much lower potential for this reaction than other chemical filters.
To guard against any possible free-radical generation and damage, we include a selection of antioxidant ingredients in all of our sun lotions. These include Green Tea, Chamomile, Edelweiss, Rosemary and Avocado oil - all of which have demonstrated antioxidant activity.