The best bar soap for your skin

by michael holloway bsc, msc

Not all soap is the same. For example,  did you know mass produced "cleansing" soaps can actually be the most damaging to your skin? Or that certain "old-fashioned" soaps have properties far superior to that of higher-priced brands? Soap can vary significantly, both in terms of it's chemical composition and it's clinical and cosmetic effects. By knowing what to look for you can find the soap best suited to your individual needs.

How Traditional Soap Is Made

Traditional soap has long been made by mixing oils (animal fat or vegetable oil) and water (most often distilled) with an alkali salt. The salt combines with the oils and undergoes a chemical process called saponification. Saponification is the process of turning oils, liquid, and alkali into soap. For making bar soap the alkali salt used is sodium hydroxide, also known as lye. Although this sounds abrasive there is no lye left in properly made soap. All of the alkali and oil have been converted into soap.
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Historically, soap was made with tallow (beef fat) or lard (pork fat). Soap makers today still make soap in the same way, except modern soap is more likely to contain coconut oil, palm oil, rapeseed oil, olive oil, and other specialty botanicals, nutrients and/or vegetable oils than animal fats. Manufacturers also add fragrance, colours, essential oils, herbs, and other ingredients to theme the soap although many of these additions do little in the way of contributing to good skin health.

True Soap

Only soap made in the traditional way, comprised of alkali salts of fatty acids (in more basic terms, oils that have been saponified with an alkali) is considered "true" soap. True soap is currently made by large manufacturers to small artisan crafters alike. True bar soap contains surfactants that reduce surface tension between oil and water. Surfactants tend to do the best job of capturing dirt and washing it away.

It was previously thought that true soap left the skin's pH unbalanced because soap is slightly alkaline with an average pH of 8 - 9. Human skin is naturally slightly acidic, with a pH of around 4.5  to 5.5. Research shows that, even after cleaning with soap, the skin returns to its normal pH very quickly. So using a pH balanced bar isn't really as important as previously believed.
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Although there are many true soaps that are all-natural, many soaps on the market today contain synthetic hardeners, fragrances, or colorants. This isn't good or bad, just something of which to be aware. If you're looking specifically for an all-natural bar, read the ingredients.

Synthetic Detergent Bars

Most bar soap you buy at the supermarket isn't technically soap at all; It's syndet bar. Syndet is a hybrid of the words "synthetic" and "detergent." Syndet bars are made from synthetic surfactants. These surfactants are made from oil, fats, or petroleum products which are processed in ways other than traditional saponification.

Instead of alkali saponified animal fats and vegetable oils, syndet bars contain ingredients that include sodium cocoyl isothionate, sulfosuccinates, sulfonates, and betaines. However, just because this soap is made with synthetic ingredients does not mean it is bad for your skin; in fact, quite the opposite. These soap-free cleansing bars can be quite gentle. Dove (the very first syndet bar launched), Cetaphil, and Eucerin bars are all good examples of gentle syndet bars.

Although we as consumers call syndet bars soap, you will never see such bars marketed this way. To be considered soap, according to the U.K government, the product must be mainly alkali salts of fatty acids. So, manufacturers can call syndets detergent bars, cleansing bars, or beauty bars, but not soap.

Glycerine Soap

Transparent soaps can be true bar soaps or syndets, with the addition of glycerin for added moisturising ability. The additional glycerin helps make them milder, but not all the time. The components of transparent soaps can still be irritating to the skin. It depends on the formulation and ingredients of the product in question. A transparent bar is not a guarantee of a mild soap.

Super-fat Soaps

Super-fatted soap is true soap that contains extra oil. This additional oil has not been saponified (hasn't turned into soap). The super-fatting improves the soap's moisturising abilities and makes it less irritating to skin. Some people however find super-fat soaps too heavy and not cleansing enough.

Combi Bars

Combination bars are exactly what they sound like. They are a combination of different types of soap designed to maximise cleansing while minimise dryness and irritation. These bars commonly combine ingredients of super-fat soap and syndet bars. Many bars on the market today are combination bars.

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choosing the right bar

Choosing the right bar for your skin can definitely feel overwhelming. However, knowing what you are looking for will help narrow your choices.

1. Decide what's important to you. 

Are you committed to natural, vegan skin care products? Then a traditional handcrafted soap like our bath bars or Deli soap would be your preferred bar. (Just remember to read the ingredient list, not all handcrafted soap is all-natural or vegan.) Is it more important that the product be inexpensive and easy to find at most stores? Syndet bars will be your best choice in this case.

2. Do you need a face or body soap? ​

A bar with excellent cleansing abilities may work great on your body. But use that same bar on your face and it's likely to be too drying. As a general rule, you'll need a more moisturising bar for the face than the body, so plan on getting two different bars. Can you use bar soap on your face? Absolutely, as long as it is gentle and non-irritating.

3. Listen to your body. ​

It doesn't matter what type of bar you're using if it's leaving your skin feeling tight, dry, or itchy, it's not the right product for you. The right bar will leave your skin feeling clean and refreshed, but not stripped. Just because a bar works wonders for your friend, doesn't necessarily mean it's right for you. Everyone's skin is unique and reacts differently to soap and cleansers. If possible, try out samples of products before you purchase them (we provide free samples upon request). Really pay attention to how your skin feels, not just immediately after you're finished washing but after using the product for several days or weeks.

In Summary ​

Your NHS dermatologist is an expert on skin, so will have some great suggestions for you. But to sum up, one type of bar soap isn't inherently better or worse than any other. Some true soap bars are gentle and some are drying; some syndet bars are gentle and some are drying. Don't get too worried  trying to identify what type of bar you're using. If you like the way a soap bar makes your skin feel, you like the scent, and the price, then it's good for you.