Posted 21 March 2008 - 02:24 AM
I've been wondering something along these lines also. If I understand correctly, we want the filters in the sunscreen to be absorbed into the upper layers of the skin, or else we would not be told to apply sunscreen 20-30 minutes before exposure. But we also DON'T want it to be absorbed into the deeper layers of the skin, or it will cause free radical damage that is actually worse than with no sunscreen at all. This is why we are told to RE-Apply every 2 hours. So, if we are using any other skincare products, should they go under the sunscreen, over the sunscreen, or not be used at the same time? Is there any tactic for slowing the absorption of the filters in order to stretch out the 2 hour window?