My husband asked me if I could put any additive into my lip balm to give it any SPF? I make lip balm just for our family and give out a few as gifts and I have heard you can't claim it to have a certain SPF if you sell it, so this wont be a problem. Do I have to modify my current recipe, or can I just add the.....ummm, is it zinc oxide, or titanium dioxide to it? I have never tried this before so any direction would be welcomed! I have no idea how much to add. I usually make up about enough lip balm base to fit into a pint size mason jar and I just scoop out a little at a time as needed to fill up containers.