Lather up, grab a blade and whip it off. That’s all there is to shaving right? Wrong. Daniel Bennett discovers the science behind whisker trimming
Dry beard hair is as tough as copper wire according to tests carried out at Gillette’s Technology Centre. Applying a hot flannel or having a shower before shaving is the easiest way to soften it.
The heat melts the grease (or sebum) that naturally gathers on the skin, allowing the hair to absorb the water. As the hair cells swell, the bristles soften and expand, reducing the force needed to cut through each one.
Water hotter than 48°C will also destroy 95 per cent of bacteria that can cause irritation after shaving.
At its sharpest point, each blade is only hundreds of atoms wide (25 nanometers), so it blunts fairly quickly. Gillette guarantees its blades’ sharpness for 10 shaves, which is a good rule of thumb, but this varies from person to person.
Your skin naturally produces an acidic layer or ‘mantle’ that wards off bacteria. Shaving removes this, leaving your skin temporarily exposed and allowing water to leave your skin cells much quicker. Alcohol-based aftershaves will keep the bugs at bay, but it can dry out your skin.
A moisturiser will temporarily replace this layer, while your body catches up. For some men this will feel unnecessary, but for others with more sensitive skin, it could help ease pain after shaving.
A shaving cream or oil has two functions. First to lubricate the cutting action, and second to provide a protective barrier between the blade and the skin. Oil-based shaving products are ideal in this respect as they are less likely to be bulldozed out of the way by the razor’s head.
To generate the ‘slip’ for the cut, shaving products contain a detergent – though at a much smaller concentration than you’d find in your car wash.
Creams with active ingredients like aloe vera usually contain molecules that are positively charged called cations to maximise their effect on our negatively charged skin but it’s debatable whether they sit on the skin long enough to have an effect.
While going against the grain will provide the closest shave, it’s also the most common cause of soreness or razor burn after a shave.
When cutting against the direction of growth, the blade bends each bristle back against itself. This tugs at the nerve endings and tears the hair as it bends back on itself. Bacteria can then rush into this micro-tear causing redness and irritation.
Shaving downwards with the direction of the growth avoids this, and taking a second pass across the grain will provide a closer shave.
Once upon a time one blade was enough to keep a man’s beard at bay. Now top brands insist that we need at least four blades on a razor with a name worthy of an atomic weapon just to keep up.
That said, the multi-blade system is based on grounded science. As the first blade cuts a hair, it also pulls it further out of the follicle by several nanometres in preparation for the next blade. This happens with each of the five blades meaning that you actually cut the hair beneath the surface.
Men tend to place between 500g and 1.5kg of force on their skin when they shave. Loaded on to one blade this can cause the skin to bulge, creating resistance. But placed over five surfaces, the effect is minimised, allowing the blade to move smoothly across the skin.
Will we see a seven-bladed razor in the future? Possibly, but only when manufacturers figure out a way to fit that many on to the same surface area.
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