Hello, the recipe should use heat. To help dissolve the ingredients together well. In particular, some ingredients are powdered, such as
BEMT ,
DHHB must be sufficiently heated. to achieve complete dissolution. If not completely dissolved Sun protection efficiency will not be fully in. For the SPF / PA, the team can not tell clearly. The only way to know for sure is to send a lab to measure it. In the case of formulas derived from the originals that are already on the market It may refer to the SPF / PA value that the original manufacturer has notified me (this does not mean that Every manufacturer will always tell you the exact SPF/PA value. The only way to know for sure Probably still sending a lab to check)