I have a sunscreen with active ingredients Titanium Dioxide 4.9% and Zinc Oxide 4.7%. I would like to use it on top of P&R Day Cover or possibly Emu Oil/Squalane. Will this block the Zinc Oxide from converting to Zinc Ions? I found a post from Dr Pickart saying that "Yes, using Day Cover under the strong sunblocks is a good idea. The Day Cover's lipids will block the uptake of ingredients from the sunblock." (https://healthyskin.infopop.cc/eve/forums/a/tpc/f/5990018252/m/6420072665?r=5050073665#5050073665)

Will Squalane or Emu Oil also do this?

Has anyone experienced indications that Day Cover does not block the uptake of Zinc Oxide?

Either Day Cover or the lipids will block most of the zinc.

Thanks Dr P, do you have a recommendation of a percentage of zinc oxide not to exceed?

5% would be a good guess. But the best approach is to put a barrier between the zinc oxide and your skin. A light amount of Day Cover would make a good barrier.