pH of Soap: What Is It and Why Does It Matter?

ph of soap

When it comes to the science of making soap, it's crucial to make sure the final product is both effective and safe for the skin. pH balance is one of the most critical factors that help the skin stay healthy, but there's so much conflicting information about the pH of soap! In this article, you will learn what soap makers must know about pH.

What Is pH of soap?

In chemistry, pH stands for 'potential of Hydrogen.' It's a scale from 0 to 14 that measures the hydrogen ion concentration in an aqueous solution of a substance and is used to specify how acidic or alkaline it is. To have a pH, a substance must be a water-based (aqueous) solution or, if a solid, it must be in a water-based solution. This means substances like gasoline and vegetable oil do not have pH. Soap bars don't have a pH either until you add water by using them.

A pH of 7 is neutral. Anything above that level is alkaline, and anything below it is acidic. Extreme points on both ends (1—very acidic and 14—very alkaline) are bad for us, but it's safe to use both alkaline soap and acidic products.

For reference, here is the pH of some common household acidic products. Lemon juice has a pH of about 2, black coffee about 4.5, and milk about 6.6. Water is about 7. And what is pH of soap? It depends on the manufacturer and the ingredients. pH testing natural soap (when all base oils are from plants) typically shows a result between 8 and 10, with most landing between 9 and 10.

pH of Castile Soap

Castile soap was first made in the Mediterranean and then spread to Europe. Today, it's a vegetable-based alternative to traditional mass-produced soap because it is free of animal fats and doesn't contain synthetic ingredients. Traditionally, castile soap was made with olive oil, but today, it refers to soap made from plant oils, such as coconut, sunflower, almond, castor, and hemp oils that give the soap its luxurious lathering and moisturizing properties. More generally, castile soap refers to the liquid version of soap made from plant-based oils. Like all true soap made with lye and oils, the pH of Castile soap in its natural state is between 9.0 -11.0.

Castile soap can be used as a beauty product and a household cleaner and even makes a great pet shampoo. Our collection of soap that we offer for private label use also includes liquid Castile soap available in multiple scents as well as Unscented. Botanie Castile soap is made with an 81% organic base that's perfect for skin, hair, and general all-purpose use. For example, the ingredients of our Lavender Castile Soap are saponified oils of sunflower and coconut, vegetable glycerin, pure essential oils of lavender and lavandin, and rosemary extract. You can purchase Botanie Castile soap starting from 1 gallon.

pH Level of Soap: Why Is It Important?

The pH level of soap we use on our skin matters because our skin is protected from harmful bacteria and other pathogens by a protective acid mantle (that also has a pH). The acid mantle is a very thin, slightly acidic film on the skin's surface that helps maintain the optimal amount of healthy bacteria and flora on the skin surface, so it remains healthy, balanced, and protected and looks hydrated, smooth, and soft.

On average, the acid mantle has a pH level of 5.5, with some variance between 4.5 and 6.2, depending on such factors as age, gender, ethnicity, climate, and body chemistry. So our skin is naturally slightly acidic, which enables a protective layer of bacterial flora to flourish.

In general, brief exposure to slightly acidic or slightly alkaline material doesn't harm the acid mantle. Changes to the skin's pH tend to be temporary, and healthy skin can rebalance its acid mantle in a very short amount of time. But a long-term or prolonged exposure to a high pH product (when you apply it to your skin and leave it for hours) can cause damage and negatively affect the acid mantle. The short amount of time we use soap does not have a lasting effect on the pH of our skin. For example, in a study of infants, water-only washing shows a pH rise of 1.1 while alkaline all-natural soap sees a rise of 1.2 points.

So although the pH of soap is an essential characteristic of a skincare item, it doesn't have a direct relationship to how harsh or mild a specific product is. pH should not be viewed as an indicator of whether or not a soap or other skincare product is irritable to your skin unless it has an extremely acidic or alkaline pH that could cause damage.

Best Soap for pH Balance

We know that skin is naturally acidic and all-natural bars of soap are alkaline. From this, many think it's better to use synthetic cleansers that are more acidic and, therefore, supposedly less disruptive to the skin's acid mantle. Beauty brands have started using terms like "pH balanced" to refer to products with a pH levels that are not alkaline. But is this true? What is the best soap for pH balance?

In fact, most non-alkaline soaps contain synthetic surfactants (oil-stripping foaming molecules) such as sulfates that actually strip skin of its natural oils. For example, Sodium Lauryl Sulfate (SLS) and sodium laureth sulfate (SLES) are cleansing agents commonly found in synthetic soaps because they're inexpensive and easy to work with. But they're also known to be harsh on the skin and may cause irritation. In addition, artificial fragrances or perfumes used in commercially produced soaps can also irritate the skin. Combined, surfactant cleansers with synthetic fragrance are more problematic than a properly formulated alkaline soap.

The best soap for pH balance is an alkaline all-natural soap made with nourishing oils mixed with lye (saponification reaction). It's a traditional way to craft soap that people have been using for hundreds of years. The resulting product is a combination of soap and glycerin, a natural humectant and moisturizer. When properly formulated and properly made, all-natural soap is the simplest way to cleanse your skin without harsh chemicals, and it's something people have been doing for generations.

At Botanie Soap, we produce bar soap, castile soap, foaming soap, and body wash using only certified organic oils and scented with essential oils. Our all-natural soap is colored with organic herbs and plant extracts and doesn't contain any artificial substances.

Interested in wholesale private label soap? Order our wholesale soap sample set to see what we offer and choose what you could sell under your brand. The sample set includes all our bar soap varieties and samples of our different liquid soap bases and scents.

Final Thought

There is a lot of marketing hype and buzz about using pH-balanced soaps that overlook practical science. The pH value alone doesn't determine whether soap is gentle, harsh, or even effective. Whether a skin care product is gentle or damaging is determined by its complete chemical makeup—all the ingredients used to create it. It is more important for your soap to be "formula balanced" than "pH balanced."

A high pH of soap isn't the real danger to your skin if it's made with all-natural ingredients and is well formulated. Instead, the synthetic detergents and other chemicals used in soaps and other cosmetics products to make them 'pH balanced' can be harsh to your skin and cause irritation.

Our skin is naturally protected from bacteria with the acid mantle that must be periodically cleaned of dirt and germs. And the most effective way to clean our skin is with a gentle, properly formulated alkaline soap. That's why properly made all-natural soaps with alkalinity in the 8 to 10 range do no harm at all—they are actually beneficial.

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