Samples were applied onto microscopy glass plates (Corning Life Sciences, New York, NY, USA) as thinly as possible, with a concentration of 2 mg/cm2, as per FDA methods for SPF determination [7]. Formulations were then irradiated with a custom-built solar simulator, using an UVA/UVB-emitting lamp (ExoTerra 10.0, Hagen Inc., Montreal, Canada), with optimal emission at the wavelength range of 290–390 nm. Each sunscreen was applied in four different glass slides, for distinct time exposures (in min): t = 15,t = 30,t = 60 and t = 120.