Mo wants to know…I’m confused. Since I read that surfactant-based liquid cleansers are better than soap, I have been on the look out for a good body wash preferably fragrance free. But now I discover that Dove Bar / Vanicream Bar etc. are not soap but Syndets. What does that mean? There are also Syndet base Liquid face & body washes. What do I pick up?
Right Brain comes clean: It’s easy to understand why people get confused by terms like soap, surfactant and syndet. Personal care marketing companies often hijack words from science and repackage them as friendly marketing messages. Unfortunately, everyone’s marketing message is different so words lose their focused definitions. That’s what has happened with these words. We’ll try to clear it up – busting beauty myths like this is what we do best!
Surfactant Cleaners
Almost all cleansing products are based on surfactants. These molecules have a special construction which 
makes them compatible with both oils and water. Since oil and water do not usually mix, you need surfactants to remove oils from skin and hair. Soaps and syndets are all surfactants. Detergent is just a synonym for surfactant.
Syndet Made Simple
Syndet is a portmanteau word created by combining the words “synthetic” and “detergent”. It was made up by the beauty industry to make products based on synthetic detergents sound sciencey and special. Synthetic detergent sounds nasty, dangerous and icky. Syndet sounds high tech, fun and friendly.
A common type of Syndet like Sodium Lauryl Sulfate is made by reacting a fatty alcohols with acid.
Fatty Alcohol + Acid = Syndet
Straight Dope on Soap
Soaps were the first surfactants people used for cleaning. They are made by reacting fatty acids with a base (e.g. sodium hydroxide), a process called saponification.
Fatty Acid + Base = Soap
Three things make Soap different from Syndets.
1. Starting material. The starting material for soap is either animal fat (tallow) or natural oils. Syndets start 
with fatty alcohols which can be distilled from petroleum or derived from natural oils. Sodium Lauryl Sulfate can be made from both Coconut Oil or petroleum distillates. A by-product of soap making is glycerin, a natural moisturizer. Syndets must be formulated with glycerin or other moisturizing ingredients.
2. Reactions with metal ions. The primary problem with soap is that it reacts with metal ions to form a material that is insoluble (can’t be dissolved) in water. This is what causes the “soap scum” you see lining people’s bathtubs and sinks. Syndets do not react like this so it is not a problem.
3. Formulating flexibility. From a formulation standpoint, syndets are much more flexible than soaps. Soaps are generally solids at room temperature and are limited in the number of ingredients you can incorporate in them. Syndets are liquids that can be thickened and made solid.
Syndet Bar
An example of a Syndet bar would be this La Roche-Posay Syndet bar
It uses standard surfactants like Disodium Cocoamphodiacetate, Coco-Betaine, Peg-7 Glyceryl Cocoate, Sodium Laureth Sulfate, etc.
Beauty Brains Bottom Line
As far as what you should get, that is up to you. If fragrance free is an issue, you could try the La Roche product. You could also try the Dove Bar or other syndet bar. The key to these things is to try different products until you find something you like. Everyone’s skin and preferences are different. Personal experimentation is your best option.
See this page for an experiment demonstrating the difference between soap and detergent.
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{ 9 comments… read them below or add one }
A natural soap is best for my skin. Important to note the difference between commercially made soap and natural soap, which this article didn’t do. The commercially made soap removes the glycerin. I no longer need lotion since I stopped using syndets on my skin.
Great article, as usual! I just recently started using a bar of soap, and realizing how much I’ve been taking syndets for granted!
A low cost, green eco friendly, healthy natural surfactant for body wash can be made from soapberry which grows on the Chinaberry tree and has been used for thousands of years. It works very effectively.
First of all, this was a very informative article. Thank you for writing it.
I use handmade natural bar soap, which, unlike factory-made soaps like Ivory, is not drying at all. In fact, as a previous poster noted, I no longer need to use lotion after I shower and shave with the soap. I would love to see an article showing that not all soap is creted equal!
We’ll work on it. It’s true that not all soap is created equal. In fact, a standard procedure during skin moisturization tests is to use Ivory soap to dry out the skin.
Does it have Aloe?
what is a good soap free bodywash that is fragrence free or mild fragrence that has little moisturizers in it.
Not exactly correct…
A soap is a very simple, low impact cleaning agent that improves water’s ability to clean particulate and oily soils. It is made in a one-step process, with no waste products, and quickly & completely biodegrades.
A surfactant is the same as a detergent. The word itself is a compression of “Surface Active Agent.” Surfactants were developed in the first place because they clean and rinse better than soap in hard water. They usually are much more aggressive cleaners. Their virtue lies in all-purpose, industrial, and specialty cleaning applications. Unfortunately, they are often used in personal body washes, for which soap is superior.
The synthetic manufacture of many surfactants, especially those built from petroleum, generates undesirable waste. Surfactants also do not biodegrade as rapidly as does soap. However, within detergents, there is a wide range in both effectiveness and ecological impact. Renewable resource plant-based detergents usually have less ecological impact than those that are petroleum-based.
Also not exactly correct and full opinion.
Soap is a surfactant that is made of fat/oil + alkali (aka Draino). By it’s very nature, the pH of soap is quite alkaline, whereas the natural pH of skin is acidic (around 5, and neutral pH is 7). One of the biggest problems of using soap for face/body/hair is its high pH which disrupts the natural pH balance. Soap dries skin and frequently causes reddening due to it’s intrinsic high pH. Glycerin in soap has been shown to cause skin Soap also leaves ‘soap scum’ on face/body/hair which is undesirable. On the contrary, synthetic surfactants have been developed especially for personal care products that overcome the short fall of soap: pH around 5, extremely low skin irritation as demonstrated by testing, and is also readily bio-degradable. Furthermore, hair and high pH create brittle, frizzy, tangled hair that looks terrible. This type damage can be masked by silicone or heavy conditioners but once its damaged, only re-growing the hair can fix it.
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