I have wavy rather than curly hair, but on some days it can be as limp and flat as a wet flag. I'm not sure why this happens, but on days when a little volume is needed, Bumble & Bumble Surf Spray ($24.99) can be a help. Be warned, unless you have very greasy hair, this product will make your hair very dry and should be used sparingly and not every day.  The culprit is magnesium sulfate, which soaks up oil. And, given that there isn't much else but water and algae, that got me to wondering what magnesium sulfate has to do with making waves.

It turned out to be one of those questions for which it is hard to get a straight answer. Here's what I've pieced together. Magnesium sulfate is Epsom salts, most commonly thought of as something to add to bathwater to soothe aching muscles. It is a sulfate mineral that easily dissolves in water. Hair curls because the keratin proteins contain amino acids called cysteines. These cysteines link to each other by disulfide bonds (two sulfur atoms connected to each other). The closer together that those sulfor atoms get, the curlier the hair. So the sulfor in the magnesium sulfate increases the bonding and helps the hair retain bounce, waves and the style it has been set into. Or something like that.

Now that we've worked that out, its easy to understand how relaxers and perms work. Relaxers simply break these disulfide bonds and cap them so that they cannot reform, while the chemicals in perms break them and recombine them.

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Ingredients for Bumble & Bumble Surf Spray:

Water (Aqua), Magnesium Sulfate, Macrocystis Pyrifera (Kelp) Extract, Algae Extract (Algae), Isoceteth-20, Potassium Sorbate, Citric Acid, DMDM Hydantoin, Fragrance (Parfum).