Absorption ov UV radiation by sunscreens

On an approx. 4 cm wide and approx. 30 cm long strip of PE foil very thin layers of different sun protection creams are applied (rub and wipe with a handkerchief with slight pressure). The absorption capacity for UV light from an LED flashlight (λ = 365 nm) is tested by holding spots without applied cream and spots with applied creams one after the other between the UV lamp and a sample fluorescing at 365 nm (e.g. a fluorescein solution in a Petri dish, a filter paper painted with a highlighter, etc.).

• A reduced fluorescence can be observed by the UV absorbing part so of the PE foil.

The distances and concentration of the fluorescein solution depend on the creams tested and the performance of the UV LED flashlight used.