What Actually Makes a Bar of Soap Gentle?
People throw the word “gentle” around a lot when they're talking about soap.
Gentle soap. Natural soap. Soap for sensitive skin. Goat milk soap.
But what the hell does gentle actually mean?
Because I've used plenty of things labeled gentle that left my skin feeling about three sizes too small afterward.
And here's the slightly annoying answer: there isn't one magic ingredient that makes a bar of soap gentle.
Not goat milk. Not olive oil. Not shea butter. Not the fact that somebody made it by hand while wearing an apron and listening to Lambrini Girls loudly enough to concern the neighbors.
It comes down to the whole recipe—and how that recipe cleans your skin.
First: soap is supposed to clean you
Obvious, I know. But this is actually where the whole gentle-soap thing starts.
Soap works because its molecules can grab onto oils and grime on one end and water on the other. When you rinse, away it all goes.
Excellent. We are clean.
Except your skin naturally has oils of its own, and we don't necessarily want to send every last bit of those down the drain.
A soap that cleans too aggressively can leave your skin with that tight, squeaky feeling afterward.
And despite what years of advertising may have taught us, squeaky clean isn't necessarily better.
Your skin isn't a casserole dish.
The oils in the recipe matter
When I'm making a soap recipe, I'm not just picking oils because they sound nice on a label.
Different oils do different things in a finished bar.
Some help make the bar hard and long-lasting. Some make big fluffy bubbles. Some contribute a creamy lather. Some are particularly good at cleansing.
You want a balance.
Coconut oil, for example, makes fabulous bubbles and is a really effective cleanser. That's why you'll find it in a lot of handmade soap—including mine.
But that doesn't mean that if some coconut oil is good, ALL THE COCONUT OIL must be better.
A soap made with a very high percentage of coconut oil can be more cleansing than some people's skin appreciates.
That's really the trick to a good soap recipe. It isn't about cramming every trendy oil and butter known to mankind into a single bar.
It's getting the ingredients to play nicely together.
Then there's something called superfat
Time for a little soapmaker geekery.
Traditional soap is made when fats or oils react with lye through a process called saponification.
And since we're talking about gentle soap, this is probably a good place to deal with the elephant in the room:
Yes, real soap is made with lye.
When a soap recipe is formulated and made correctly, the lye is used up during saponification. You're not washing yourself with a bar full of free-floating lye waiting to eat your face.
Soapmakers can also formulate a recipe so there's more oil than the lye can convert into soap.
That's called superfatting.
It's another tool we can use to control how cleansing—or how mild—a finished soap feels on your skin.
And no, more isn't automatically better here either. Too much extra oil can create other problems in a bar.
There's that annoying answer again: balance.
Soapmaking is basically chemistry wearing a cute apron.
A cute apron that apparently has very loud taste in music.
What about goat milk?
Okay. Now we're in my happy place.
I make a lot of goat milk soap because I genuinely love what it brings to a bar—the creamy lather, the feel of it, the whole experience.
Milk contains fats and naturally occurring sugars. Those sugars can help boost the lather, while the fats contribute to that rich, creamy quality people associate with a really nice milk soap.
But does adding goat milk magically transform any random recipe into the gentlest soap ever created?
Nope.
The rest of the recipe still matters.
I love goat milk as a soap ingredient. I use a lot of it. But it isn't a magic spell.
And glycerin? That's already in there
This is one of those fun little soap facts that a lot of people don't know.
You may have heard something described as “glycerin soap,” which can make it sound as though glycerin is some special ingredient that only certain soaps contain.
But glycerin is naturally created during soapmaking.
In handmade cold-process soap, that naturally occurring glycerin remains in the finished bar.
Glycerin is a humectant, meaning it attracts water. It's part of what can give handmade soap such a lovely feel on the skin.
It's also one reason a handmade bar sitting in a humid bathroom can sometimes get a little...sweaty.
Soap has moods, like a Gen-Xer whose field of you-know-whats is empty.
Fragrance matters, too
Here's another thing that's easy to miss.
Sometimes the soap itself isn't what someone's skin dislikes.
It might be the fragrance. Or an essential oil. Or a botanical. Or another additive that sounds perfectly lovely but does not agree with that particular person's skin.
Which brings me to one of my favorite little hills to die on:
“Natural” and “gentle” are not synonyms.
Poison ivy is natural.
I don't recommend bathing with it.
If your skin tends to be reactive, simpler can sometimes be better. An unscented or simply formulated bar may be a better starting point than something containing seventeen essential oils, flower petals, exfoliating seeds, clay, glitter and the hopes and dreams of the soapmaker.
Your shower does not need that kind of pressure.
So how do you actually choose a gentle soap?
Unfortunately, there's no single ingredient you can find on a label that guarantees a soap will be perfect for your skin.
What you can do is look at the whole bar instead of chasing one superstar ingredient.
If you're prone to dry or sensitive skin, consider starting with a simpler soap. Pay attention to fragrance if you already know you're sensitive to it. And don't assume something will be gentle just because the label says natural, herbal, handmade—or even goat milk.
Most importantly, pay attention to how your skin actually feels after you use it.
Does it feel clean and comfortable?
Great.
Or are you climbing out of the shower feeling like your skin suddenly shrank half a size?
Maybe that's not your soap.
Your skin gets a vote.
Gentle doesn't have to mean boring
This is probably obvious considering I make soaps with names like Dirty Girl and Sexy Man, but I don't think taking care of your skin needs to feel medicinal.
I want the good stuff, too.
Beautiful lather. Great scents. A bar that feels good in your hands and that you actually look forward to using in the shower.
The goal is to get all of that into a soap that cleans well without trying to strip your hide off in the process.
That's what I'm after when I formulate a soap.
Not the most bubbles.
Not the longest ingredient list.
Not whatever ingredient happens to be having its fifteen minutes on TikTok.
Just a really good bar of soap that does its job and leaves your skin feeling good afterward.
Which, frankly, shouldn't be such a revolutionary concept.
Want a gentler place to start? Take a peek at our goat milk soaps and skin-loving bars, handmade in small batches in New Hampshire.
