The science of post-shave skin
Everything Lyscia is built on, in one place. What razor burn actually is. What potassium alum does on skin. Why the fixes most people try do not address the real cause. Written to be read once and referred back to.
The problem
A razor does not only cut hair. It drags across the skin and lifts off the top layer of dead cells. That leaves the fresh layer underneath exposed. In the next few hours, friction, sweat, and bacteria attack it. The result is what people call razor burn: red patches, small bumps, a hot tight feeling. It is not an allergy. It is a wound, small, spread over a large area.
Related skin problems
Razor burn is one of a small family of post-shave problems. Ingrown hairs, strawberry legs, folliculitis, and simple irritation all share a common cause: the follicle and the skin around it get inflamed after shaving, and the top layer of skin does not close fast enough.
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- How to prevent strawberry legs
- Shaving irritation vs folliculitis
- Ingrown hairs after shaving
- Skin rash after shaving
- Shaving rash vs razor burn
The mineral
Potassium alum is a naturally occurring salt. Chemical name potassium aluminium sulphate. Chemical formula KAl(SO4)2·12H2O. On skin, applied wet, it acts as an astringent: it makes the top layer of tissue contract slightly. The tightening closes the shallow wound the razor made. It is one of the strongest natural astringents that is still safe for external skin contact. That combination is rare, which is why alum has stayed in use for over two thousand years.
The context
People confuse potassium alum for post-shave use with aluminium in antiperspirant deodorants. They are different compounds used for different purposes. The concerns you may have read about aluminium in cosmetics come almost entirely from studies of a different compound, applied daily in a different way, close to different tissues.
The fixes that do not work
Aloe cools the skin for a minute and does nothing to close the wound. Body lotion covers the skin with oil, which can trap bacteria against fresh skin. Aftershave is mostly alcohol, which kills some bacteria but stings, dries the skin, and does not close the wound.
- Alum stone vs aftershave
- Alum stone vs aloe vera
- Alum stone vs witch hazel
- The best thing to put on skin after shaving
- How to soothe irritated skin after shaving
The routine
Six steps, five minutes the first time, autopilot after that. Warm shower. Real shaving product. Shave with the grain. Rinse cool. Alum stone. Pat dry.
- The complete legs guide (cornerstone)
- How to use an alum stone
- How to shave without razor bumps
- Sensitive skin shaving routine
- Why does my skin burn after shaving
- How long does razor burn last
The product
The Lyscia Crystal is one solid piece of potassium alum in a clear drying case. Nothing added. One ingredient, one job. Shop the Crystal — €39