Are botanicals really “useless” in soap? - A scientific, practical, and honest look at what happens with plants in cold process soap
This article was inspired by a recent exchange on Instagram that, quite honestly, left me both frustrated and motivated.
Under one of my posts about botanical soap, there was a depbate as someone said: "there is no evidence that the herbs used in soaps really do anything on the skin". According to her, lye destroys everything, botanicals provide no benefit, and even superfatting is essentially a myth that does nothing for the skin.
What followed was a long comment thread where several professionals, including myself, explained the chemistry, the process, and the science behind botanicals, infused oils, and superfatting. I linked peer-reviewed research. We explained it from multiple angles. Other experienced makers, chemists and professionals joined in.
That exchange is exactly why this article exists.
Not to attack anyone, but to educate properly, transparently, and responsibly. And to gently warn newer soap makers to be cautious about cheap courses and oversimplified claims that dismiss both science and real-world formulation experience.
The myth: “Lye destroys everything”
Let’s start with the most common claim.
Yes, lye is alkaline.
Yes, saponification is a chemical reaction.
No, that does not mean everything botanical is destroyed.
What actually happens in cold process soap is far more nuanced.
Lye reacts with fatty acids, not directly with all plant compounds. Many botanical constituents, such as polyphenols, flavonoids, terpenes, and certain antimicrobial and anti-inflammatory compounds, are not fully destroyed during saponification.
What does significantly impact delicate compounds is heat, not lye itself. The heat released during saponification can degrade heat-sensitive vitamins and compounds, especially if high temperatures are used early in the process. This is why timing matters.
Adding botanicals later, working at lower temperatures, and using infused oils changes the outcome dramatically.
What science actually says about herbal soaps
Scientific reviews of herbal soap formulations clearly describe why botanicals are used and what they contribute.
From the research:
“Plant-derived ingredients and extracts are incorporated into herbal soaps for their antibacterial, antioxidant, anti-inflammatory and skin-nourishing properties. These formulations are associated with gentler skin effects and functional benefits such as moisturising and calming the skin compared to harsher synthetic products.”
Source:
This does not claim soap is medicine. It does not claim cures. It simply confirms that botanical components do survive in functional ways and contribute to skin comfort and performance.
A chemist’s perspective (and why this matters)
To go deeper, I discussed this topic extensively with Arwa Mohsen Yousef, owner of MOJ Soap in Egypt, a chartered chemist specialised in organic chemistry and clinical analysis, and a soap maker with her own laboratory and production facility.
I trust her expertise fully, and I have personally learned a great deal from her.
Her key insights, simplified and translated into practical terms:
- When herbs are infused in oil for around six weeks and stored in a dark environment, the oil extracts antimicrobial, anti-inflammatory, and healing compounds, along with scent and therapeutic properties.
- Vitamins are mainly degraded by heat released during saponification, not by lye itself.
- Even so, trace amounts of vitamins A and D have been detected in soaps made with pumpkin purée, carrot, avocado, and milk, even at higher temperatures.
- Milk soaps, despite higher soaping temperatures, still show detectable vitamin traces in testing.
This aligns with what many experienced formulators already know: soap is not a vitamin delivery system, but it is not chemically barren either.
Superfatting: Not a myth, but applied chemistry
Another claim made in that Instagram exchange was that superfatting “does nothing” for the skin.
This is chemically incorrect.
Superfatting means that lye is the limiting reagent, and oils are present in excess. In cold process soap, not all oils are converted into soap.
When you wash with cold process soap, the soap molecules rinse away, but excess oils do not fully rinse off. They remain on the skin surface, interacting with the skin’s lipid layer.
This is why:
- Cold process soap does not leave the chalky white dryness typical of synthetic shower gels
- Skin feels conditioned rather than stripped
- Oils infused with botanicals are particularly effective in this context
From a chemistry standpoint, this is simply surface chemistry and solubility.
Skin is porous.
“Like dissolves like.”
Lipids interact with lipids.
Small quantities matter. Molecular size matters.
A simple analogy Arwa shared:
A fingerprint can be lifted after a fraction of a second of contact. Turmeric stains marble instantly, even if wiped quickly. Oil can remove that stain because like dissolves like. That is the beauty and power of chemistry.
Are botanicals medicine? No.
Are they nourishing? Yes.
We believe it, we trust it, practice it, we live it, we teach it.
Cold process soap is not a medical treatment. Claims should never be made.
But soap can absolutely:
- Support skin comfort
- Reduce harshness
- Improve balance
- Enhance sensory experience
- Support acne-prone or inflamed skin when formulated thoughtfully
Arwa described it perfectly:
Soap is not medicine, but it behaves more like an over-the-counter support product, similar to vitamins or electrolytes during cold weather.
She also noted how customers often label bars themselves, asking for “the eczema bar”. She avoids those claims, but real-world feedback consistently shows improvement with certain formulations, such as indigo or camel milk soaps.
That distinction matters.
Why this matters for students and makers
The most concerning part of the Instagram exchange wasn’t disagreement, it was dismissal of science and experience.
When multiple professionals explain something from different angles, link research, and share real-world testing, and the response is still denial, it raises a red flag.
This is why I always encourage students to:
- Question absolutes
- Be wary of “everything is useless” claims
- Avoid cheap courses that oversimplify chemistry
- Learn from people who understand formulation, not just trends
Soap making sits at the intersection of chemistry, craft, and experience. Ignoring one of those pillars leads to misinformation.
Final thoughts
Botanicals are not useless.
Superfatting is not a myth.
Soap is not sterile chemistry.
Cold process soap is a beautifully balanced system, where formulation choices, timing, temperature, and ingredient quality all matter.
When taught responsibly, it empowers makers to create products that are not only beautiful, but genuinely supportive to the skin.
And that is exactly what education should do.
Thank you to all my fellow soap makers and educators who commented on the Instagram post. Special thanks to:
Arwa at Moj Soap
Kris at Wild Ona
Kathy at Coconut Luxe Naturals
If you would like to share your thoughts on this topic, please feel free to click/tap here and jump to the Instagram post to add your comment.
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With all my love,
