Five myths about natural cold-process soap, tested

Five myths about natural cold-process soap, tested

By James Allan, founder of Smelly Men.

Soap has more folklore attached to it than anything else in the bathroom, bar the towel nobody admits to washing. We tested five of the most common claims against the evidence. Some are myths. Some are half true, and we'd rather tell you which.

The verdicts at a glance

  1. Soap is bad for your skin: half true, and it depends which soap.
  2. Soap wipes out your skin's good bacteria: mostly a myth.
  3. Antibacterial soap cleans better: a myth, for everyday washing.
  4. All soap is the same: not quite.
  5. Sharing soap is unhygienic: mostly a myth, at home.

Myth 1: Soap is bad for your skin

Verdict: half true, and it depends which soap.

Here's the honest version. Soap is alkaline. Well-made soap usually sits around pH 8 to 10, while your skin's surface is closer to pH 5.5, so a soap wash does nudge your skin's pH up. Skin tends to settle back afterwards. A badly made bar can be properly harsh, and anyone who's used a bargain bar that left their skin feeling tight will know it.

But soap isn't one thing. In a small 2022 study (15 people per soap), an alkaline soap caused more redness than glycerine or creamy soaps did. Same family, different results. How a soap is made, what's left in it and what's added all change how it behaves on your skin.

That's where we think a cold-process bar earns its keep. Ours are made from olive oil, coconut oil and shea butter, with the glycerine left in and no SLS, synthetic fragrance or palm oil. Our bet is that this makes for a kinder bar than a bargain one. We say bet because nobody has tested bars like ours head to head, so the evidence points that way without proving it. Try one. If your skin feels better, that's the only proof that counts.

Two other things worth knowing. Surfactants of any kind, natural or synthetic, can strip skin, and some shower gels are as drying as some soaps. And a 'pH-neutral' bar usually isn't soap at all. It's a syndet, which can be gentler but is a different product. If you have eczema or very sensitive skin, ask your GP or pharmacist, because soap-free cleansers are often recommended.

More in Is natural soap actually better for your skin than shower gel?

Myth 2: Soap wipes out your skin's good bacteria

Verdict: mostly a myth.

Your skin's bacteria are tougher than the marketing makes out. A 2016 study of common cleansers, published in the Journal of Investigative Dermatology, found no significant change in the skin's bacterial community. In general, the microbiome bounces back after normal washing.

The one study we found that did see lasting changes was a small one on an antibacterial soap, where the shifts lasted at least two weeks after people stopped using it. That's antibacterial soap, not plain soap. Which brings us neatly to...

Myth 3: Antibacterial soap cleans better

Verdict: a myth, for everyday washing.

An antibacterial bar is usually ordinary soap with one extra ingredient. It cleans the way any soap does: it lifts the dirt and microbes off, and the rinse carries them away.

The extra ingredient needs time to work, and a normal wash doesn't give it any. In a 2015 study, a 0.3% triclosan soap and an identical plain soap performed the same over a 20-second wash. A difference only turned up after around nine hours of contact. Nobody's washing for nine hours.

A 2007 review of 27 studies found triclosan soaps no better than plain soap at preventing infectious illness symptoms or reducing hand bacteria. And in 2016 the US Food and Drug Administration (FDA) stopped 19 ingredients, including triclosan, being sold in consumer antibacterial washes, because makers hadn't shown they worked better than plain soap and water.

In fairness: hospitals do use antibacterial washes, such as chlorhexidine, in targeted ways, and that's a different job. And most of the research is on triclosan, which has now gone from US consumer soaps, so newer ingredients have less evidence either way.

The fuller version is in Do you need 'warrior' soap for jiu jitsu?

Myth 4: All soap is the same

Verdict: not quite.

Soap is one of the oldest manufactured things on the planet. Clay cylinders from ancient Babylon, around 2800 BC, hold a soap-like substance, and early clay tablets from Mesopotamia describe heating oil with wood ash. The Egyptians' Ebers Papyrus, from around 1550 BC, describes mixing animal and vegetable oils with alkaline salts, for washing and for treating skin conditions. By Roman times, Pliny the Elder was writing about soap made from tallow and ashes. The basic recipe, fat plus alkali, has barely changed in thousands of years.

And all that time, every bar came with its glycerine. Nobody knew it was there until the Swedish chemist Carl Wilhelm Scheele found it in the late 1700s. In 1823 the French chemist Michel Eugene Chevreul showed that fats are made of glycerine and fatty acids, and that making soap splits them apart: the fatty acids become soap, and the glycerine is left over.

It didn't stay that way. Industry learned that glycerine is valuable. It's the raw material for nitroglycerine, which Alfred Nobel turned into dynamite in 1867, and it ended up in lotions and creams too. Many commercial makers now recover it and sell it on, so many mass-market bars contain less of it. Same stuff, very different careers. In a cold-process bar, it stays where it was born.

Is that a good thing? There's decent evidence that glycerine is kind to skin. A 2008 review in the British Journal of Dermatology found it improves skin hydration and barrier function, protects against irritants, and improves dry skin conditions, including atopic dermatitis. In a 1999 study, glycerol sped up the recovery of skin barriers damaged by repeated washing with a harsh detergent.

Now the honest bit. Those studies used glycerine left on the skin, in creams and lotions. A bar gets rinsed off, so how much stays behind isn't known, and nobody has tested a bar like ours against a bargain one. The nearest evidence is that small 2022 study, where a glycerine soap caused less redness than an alkaline one.

So here's our bet: a bar with its glycerine left in, made from real oils and butters, is a kinder bar than one stripped of it. The evidence points that way. It doesn't prove it, and we'd rather say so.

Myth 5: Sharing soap is unhygienic

Verdict: mostly a myth, at home.

Ever noticed how nobody wants to use someone else's bar? The evidence says you can relax. Studies going back to 1965 found no sign of germs being passed on when people washed, even when the bars were loaded with bacteria on purpose. UK hospital guidance still prefers liquid soap as a precaution, and anyone with a skin infection should have their own bar. For the bar in your own bathroom, that's about it. And if you'd rather have one each, nothing wrong with that either.

The full evidence is in Is it unhygienic to share a bar of soap?

Where we fit

We sell soap, so weigh that. Our soaps are cold-process bars with the full ingredient list on the box, and the glycerine stays in. We don't claim they're cleaner or more hygienic than any other soap. Whether they're kinder to your skin than a bargain bar is our bet, not a proven fact. What we can tell you is exactly what's in them, and what isn't. Have a look at the range.

Quick answers

Is soap bad for your skin?
Half true, and it depends which soap. Real soap is alkaline and a badly made bar can be drying, but in a small study glycerine and creamy soaps caused less redness than an alkaline one. If your skin feels tight after washing, change what you use.

Does soap kill your good skin bacteria?
Mostly not. A 2016 study of common cleansers found no significant change in the skin's bacterial community, and the skin microbiome generally bounces back after normal washing.

Is antibacterial soap better than plain soap?
Not for everyday washing. In studies it performed no better over a normal wash, and in 2016 the US FDA stopped 19 ingredients being sold in consumer antibacterial washes because makers hadn't shown they worked better.

Is a pH-neutral bar the same as soap?
Usually not. True soap is alkaline. A pH-neutral bar is typically a synthetic detergent bar, or syndet, which is a different product.

Is glycerine soap different?
It can be. Glycerine is a natural by-product of soap-making that many commercial makers remove and sell on, while cold-process soap keeps it in. Glycerine is well studied as a skin moisturiser, but mostly when left on the skin. Whether a rinse-off bar gives the same benefit hasn't been proven.

Why does cold-process soap cost more than a bargain bar?
You're paying for what's in it and what's been left out: real oils and butters turned into soap, the glycerine kept in, no SLS, synthetic fragrance or palm oil, and a full ingredient list. Whether it's kinder to your skin is our bet rather than a proven fact, so try one and see.

Is it unhygienic to share a bar of soap at home?
For hand washing, the evidence says no. The exception is anyone with a skin infection, who should have their own bar.

General information, not medical advice.

Sources

Last reviewed: 11 October 2026. Next review: April 2027.

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