You might have seen skincare products advertised as pH balanced, pH neutral or pH friendly, but what does any of that actually mean? And does the pH of your soap matter?
Well, yes, it does. But first, a (very) quick chemistry lesson.
What exactly is pH?
pH is a measure of how acidic or alkaline something is, using a scale that generally runs from 0 to 14. A pH of 7 is neutral, anything below 7 is acidic, and anything above 7 is alkaline.
For example, lemon juice is acidic, pure water is neutral, and baking soda dissolved in water is mildly alkaline.
Traditional handmade soap, including the cold process soap I make at The Soap Mine, is naturally alkaline, usually with a pH somewhere around 9 to 10, although the precise figure varies between formulations and how it’s measured.
And that’s perfectly normal.
Why is soap alkaline?
It’s all down to the chemistry of soapmaking. Traditional soap is produced when oils and butters react with sodium hydroxide in a process called saponification. The resulting soap molecules are naturally alkaline when dissolved in water.
That doesn’t mean there’s dangerous, unreacted sodium hydroxide lurking in a properly made bar. The alkalinity comes from the chemical nature of soap itself.
And here’s something important: you can’t simply lower the pH of traditional soap to match the pH of your skin without changing the soap itself. Add enough acid and the soap begins to break down into fatty acids, losing the properties that make it an effective cleanser.
But isn’t our skin acidic?
Yes! Healthy skin has a slightly acidic surface, usually somewhere around pH 4.5 to 5.5. This helps support the skin’s natural protective barrier.
Washing with alkaline soap can temporarily raise the skin’s surface pH, and for some people, particularly those with sensitive or compromised skin, that might contribute to dryness or irritation, but most people can use it quite happily every day.
The overall formulation, how often you wash, the temperature of the water and your individual skin all influence how comfortable a cleanser feels to use. I’ve said it before, but this is why I spent so much time getting my soap formulation right. The balance of oils and butters matters, even though the finished soap remains alkaline.
What about pH-neutral soap?
Well, if you read yesterday’s post, you’ll know that bars advertised as pH-neutral or pH-balanced aren’t technically traditional soap at all. They’re usually syndet bars, made using synthetic detergent ingredients that can be formulated at a lower pH.
There’s absolutely nothing wrong with that. They’re simply a different type of cleansing product, NOT soap.
But if somebody claims they’ve made genuine traditional cold process soap with a pH of 5.5, I’d be rather interested to hear how they’ve managed it. Chemistry just doesn’t work that way.
So does pH really matter?
Yes, but it’s not the only thing that matters.
A soap’s pH is one factor in how it interacts with your skin, but it doesn’t tell you everything about the quality of the bar or how pleasant it will be to use. Two soaps with similar pH readings can still have very different cleansing properties because of their formulations.
My aim at The Soap Mine is to make properly formulated, well-cured soap that cleans effectively and feels lovely to use. I can’t promise that traditional soap will suit absolutely everybody, but I can tell you that many of my customers who previously thought bar soap was too drying have been pleasantly surprised.
So there’s no need to be frightened by the fact that traditional soap is alkaline. It’s simply part of what makes soap, well, soap. And now you know even more about the chemistry behind those lovely bubbles 😉
Vicki x
