No one likes the red lobster look, and science knows how you stop it. Warning: this answer is absorbing.
Asked by: Alex Round, London
Opaque sunblocks are effectively paint: particles of white titanium dioxide or zinc oxide suspended in a heavy oil. The oxide particles form an opaque barrier that reflects visible light and ultraviolet. Clear suncreams use organic compounds, such as Phenylbenzimidazole sulfonic acid, that only absorb ultraviolet wavelengths and let visible light through.
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Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.
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