Part of the show Sun Tans, Fission and Fusion
Erika in California asked:
I'd like to know if putting lemon juice on your hair really helps to bleach it, and if so, why?
The answer to this is acid catalysed oxidation. If you add oxygen and ultraviolet light to most things, like hair or clothes, then they will bleach. If you're out in the summer sun, there's oxygen in the air and sunlight, so your hairs go blond. Adding lemon juice to your hair means that you are adding an acid, and that just speeds up the bleaching process.