Q Why does my foundation sometimes turn orange during the day? When I put it on in the morning the colour is perfect, but after a few hours I can end up looking like an Oompa Loompa.

A We've all been there. Foundation or concealer can oxidise during the day and become substantially darker as it mixes with the chemicals and oils naturally present in your skin.

This is particularly common if you have oily or combination skin. Even if you have dry skin it can happen when the chemicals in a particular moisturiser and previously well-behaved foundation decide to fight on your face. The only way to beat oxidation is with a face primer to act as a barrier before foundation. Laura Mercier and Smashbox do good ones.

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