Your soap bar is missing something.

Not visibly. It looks fine. Smells fine. Lathers up, rinses off, does its job. But somewhere between the factory and your bathroom shelf, an ingredient was sneakily removed and sold to someone else at a profit. But your skin kind of needed that ingredient.

So you bought a moisturiser to fix the dryness that came from using the soap that no longer had the thing that prevented dryness in the first place.

That's the heist. And it has been running for over a century.

Let’s uncover who stole the Glycerin.

First, The Chemistry Lesson You Never Asked For (But Need)

Every bar of true soap is made the same way. You take fats or oils, and you combine them with an alkali, typically sodium hydroxide (lye). This triggers a chemical reaction called saponification.

The reaction produces two things:

1. Soap molecules (the part that cleans)

2. Glycerin (the part that moisturises)

Glycerin isn't an ingredient you add to soap. It's a byproduct that soap creates. 

In natural soap made using the cold process method, both outputs stay in the bar. You get the cleaning action and the moisture retention in one. That's the complete product.

In commercial soap manufacturing, the story goes differently.

The Part Where The Heist Happens

Shortly after World War I, soap manufacturers figured out how to extract glycerin from soap and purify it at scale. The timing wasn't accidental; glycerin was also used to produce nitroglycerin (boom), and suddenly the soap industry had a very profitable side business in a very in-demand commodity.

The war ended. The glycerin extraction did not.

Today, commercial soap manufacturers use a process called salting out: they add salt to the soap mixture, which causes the soap to curdle and rise to the surface. They skim off the soap, then distil and decolourise the remaining liquid to recover pure glycerin.

That glycerin is then sold to cosmetics companies, pharmaceutical manufacturers, food producers, and, in a particularly neat piece of circular irony, to the same brands that also sell moisturisers and lotions.

Their soap dries you out. You buy their cream. Everyone wins except you.

What Glycerin Actually Does To Your Skin

Before this starts sounding like a conspiracy theory, here's the science.

Glycerin is a humectant. That's the technical term for an ingredient that attracts and retains water. Specifically, it pulls moisture from the environment and from the deeper layers of your skin into the outermost layer and holds it there.

Published research confirms that glycerin is a key molecule in skin hydration, maintaining the water content and elasticity of the outermost layer. A separate study found that 10% glycerin outperformed both 10% propylene glycol and 10% urea (two common synthetic alternatives) in providing skin hydration over a three-hour window.

Your skin actually produces its own glycerin. Through a transporter protein called aquaporin-3, glycerin moves from the dermis upward into the epidermis, keeping the outer layers hydrated from within. Cold-process soap's natural glycerin content essentially supplements your skin's own system. It works with your biology rather than against it.

Remove the glycerin from soap, and what you have is a product that removes dirt effectively but provides no moisture in return. The skin is left to recover on its own, and it will, because your skin is good at its job. But it takes time, it costs energy, and if you're stripping the glycerin twice a day, every day, the recovery never fully catches up.

The pH Problem Is Also Real

All soap made through saponification is alkaline. Commercial soap typically sits at a pH of 9 to 10. Cold-process natural soap sits a little lower, but it's still on the alkaline end of the scale.

Your skin, for reference, likes to sit between pH 4.5 and 5.5. This is called the acid mantle — a thin protective film that keeps your skin barrier intact, your microbiome balanced, and harmful bacteria from taking up residence on your face.

Research published in the Indian Journal of Dermatology confirms that washing with alkaline soap can raise skin pH by a mean of three units for up to 90 minutes post-washing. The skin's buffering mechanisms will work to bring it back down, but frequent daily use of alkaline cleansers makes sustained elevated pH more likely, which in turn compromises barrier repair functions.

So the honest answer is: no soap is perfectly pH-neutral for your skin. Every wash is a mild disruption.

What determines how well your skin recovers from that disruption is what else is in the bar. A soap that retains its natural glycerin gives your skin the moisture it needs to restore balance. A soap that has been stripped of glycerin and filled with synthetic substitutes and synthetic fragrances asks your skin to recover from a pH disruption with no tools to do it.

What Goes In Instead

After removing glycerin from commercial soap, manufacturers don't just leave the void empty. Something has to replace it, or the bar would be obviously terrible, and people would stop buying it.

The most common replacement is propylene glycol, a synthetic humectant derived from petroleum. It does a serviceable job of creating the sensation of moisture in the short term. The US Agency for Toxic Substances and Disease Registry (ATSDR) includes it in its Toxic Substances list and notes potential respiratory effects from prolonged exposure, though it is classified as generally recognised as safe by the FDA for cosmetic use at the concentrations typically used.

The EU, for context, has restrictions on its concentration in cosmetics.

We're not here to tell you that propylene glycol is dangerous. It's probably not going to hurt you. But here's the thing: your skin already knows how to process and use glycerin. It produces glycerin. It has aquaporin-3 channels specifically designed to transport glycerin. It doesn't have any such relationship with propylene glycol.

Replacing something your skin actively uses with a synthetic approximation, in order to sell the original thing separately, is a business model. A clever one. But it's not skincare.

Commercial Soap Also Does This

While we're opening things up: many commercial "soap" bars aren't technically soap at all.

To be legally classified as soap in most jurisdictions, a product must be made through saponification. If a product uses synthetic detergents like sodium lauryl sulfate (SLS) to clean instead, it cannot legally be called soap. Which is why you'll notice a lot of shelves lined with products called "beauty bars," "cleansing bars," or "moisturising bars”. Have a peek at the label the next time you see a bar. 

SLS is an aggressive surfactant. It cleans so effectively that it strips the skin's natural oils along with the dirt. Brands then add small amounts of conditioning agents to offset the stripping, which is a bit like turning the heat up and the air conditioning on simultaneously and calling it climate control.

In a bar that uses neither the saponification process nor natural glycerin, you are genuinely just using mild detergent on your face.

What Cold Process Soap Actually Is

We make cold process soap. Here's what that means and why it matters.

Cold process soap is made by combining oils and lye, then pouring the mixture into moulds and allowing the saponification reaction to complete at room temperature over time. The "cold" in cold process refers to the fact that no external heat is applied during saponification, which matters because heat can degrade certain beneficial compounds in the oils.

The full reaction and stabilisation takes time. We cure our bars for a minimum of six weeks before they reach you. Not because we're slow. Because rushed soap isn't finished soap.

During those six weeks:

• Saponification completes fully

• Excess water evaporates

• The bar hardens and lasts longer

• The pH gradually moderates as the bar matures

Nothing is removed from a cold process bar. The glycerin your skin needs stays in the bar. The fatty acid profiles of the oils, which contribute to the skin feel, the lather quality, and the conditioning properties, remain intact. Superfatting (using slightly more oil than the lye can fully convert) means the finished bar contains a small percentage of free, unsaponified oils that sit on the skin and contribute to that non-stripped feeling after washing.

How To Read Your Current Soap Label

One practical thing you can take from this.

If your current soap retains its natural glycerin, "glycerin" will not appear on the ingredient list because it's a byproduct of the process, not an added ingredient, and INCI labelling rules don't require it to be listed separately. Its presence is implied by the saponification process itself.

If you see "glycerin" listed on a commercial soap label, it means glycerin was added back in after being extracted, a small percentage, for marketing purposes.

If you see a long list of ingredients ending in phrases like "sodium lauryl sulfate," "propylene glycol," "tetrasodium EDTA," or "BHT," you're likely looking at a synthetic detergent bar. It might be called soap. It is not soap.

And if the label says "beauty bar" or "cleansing bar" instead of "soap"? That's legalese for ‘skin detergent’.

The Version That Takes 30 Seconds

You pressed for time? Here it is:

Glycerin is a natural byproduct of soap-making. It keeps your skin moisturised. Most commercial manufacturers remove it and sell it separately for profit. They replace it with cheaper synthetic alternatives. Then you buy moisturiser to compensate for the dryness the soap caused.

Cold process soap doesn't do this. Nothing is removed. The glycerin stays. Your skin gets the whole product.

That's the heist. Now you know it's happening.

Mr. Macha is a cold process soap brand built for the South Asian man. Every bar cures for a minimum of six weeks. No shortcuts. No chemical fillers. No removed glycerin. We're currently in development — follow us @MrMachaSoap to be the first to know when we launch.

References

The scientific claims in this article are drawn from the following peer-reviewed sources. We link to primary research wherever possible so you can read the actual data.

On glycerin as a key molecule in skin hydration and the AQP3 transport pathway Hara M, Ma T, Verkman AS. (2002). Glycerol replacement corrects defective skin hydration, elasticity, and barrier function in aquaporin-3-deficient mice. Proceedings of the National Academy of Sciences. https://pmc.ncbi.nlm.nih.gov/articles/PMC165880/

On glycerin outperforming propylene glycol and urea as a skin humectant Sagiv AE, Dikstein S, Ingber A. (2001). The efficiency of humectants as skin moisturizers in the presence of oil. Skin Research and Technology, 7(1), 32–35. https://pubmed.ncbi.nlm.nih.gov/11301638/

On glycerin's comprehensive effects on skin barrier function and the AQP3 pathway (review) Fluhr JW, Darlenski R, Surber C. (2008). Glycerol and the skin: holistic approach to its origin and functions. British Journal of Dermatology, 159(1), 23–34. https://pubmed.ncbi.nlm.nih.gov/18510666/

On alkaline soap raising skin pH by a mean of three units for up to 90 minutes Mukhopadhyay P. (2011). Cleansers and their role in various dermatological disorders. Indian Journal of Dermatology, 56(1), 2–6. https://ijdvl.com/acid-mantle-what-we-need-to-know/

On cleanser pH and skin barrier integrity (Journal of the American Academy of Dermatology) Ananthapadmanabhan KP et al. (2017). Impact of cleanser pH on maintaining a healthy skin barrier. Journal of the American Academy of Dermatology. https://www.jaad.org/article/S0190-9622(17)31962-X/abstract

On propylene glycol — FDA GRAS classification US Food and Drug Administration. 21 CFR §184.1666 — Propylene glycol. https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=184.1666

On propylene glycol — ATSDR Toxic Substances listing and respiratory concerns Agency for Toxic Substances and Disease Registry (ATSDR). (1997). Toxicological Profile for Propylene Glycol. US Department of Health and Human Services. https://www.atsdr.cdc.gov/toxprofiles/tp189.pdf