Inside the Bottle: Shampoo

Before we talk more about Hair Wash and how we’re changing the status quo around hair products in general, let’s start with the basics. What is shampoo anyways?

Just like a cake, shampoo has an ingredient list. And just like a cake, these general ingredients are what make a cake, well, a cake. Take flour for example. There is all-purpose flour, whole-wheat flour, almond flour, etc. You get the idea. And so it is with shampoo.

Basically, shampoo comes down to a few general ingredients.

  • Water (in liquid shampoos)
  • Surfactants
  • Conditioners
  • Thickening Agents
  • Chelating Agents
  • Fragrance
  • Preservatives

Now you’re probably wondering why the ingredient list on the back of your shampoo bottle is so long.  In terms of the chemistry of shampoo, to get the modern, scientifically-advanced shampoo you are used to, you do need more than 6 ingredients. To keep it simple, here is the breakdown of the general ingredient list.


In a liquid shampoo, water is the primary ingredient. On average, water makes up 80% of the shampoo by weight. Water acts as a solvent to deliver the other ingredients that have more necessary functions in a shampoo. With the innovation in raw materials, like the movement away from harsh detergents like sulfates, water is not serving the reduction in irritation as it used to. The ingredients we are using now are more mild than the typical sulfates that were previously used, giving us the opportunity to move away from water as a primary ingredient in shampoo.


Surfactant is short for surface active agent. Surfactants decrease the interfacial tension between two physical states. Essentially, that means surfactants allow for a change in how two phases interact with each other. In shampoo, surfactants allow for oil and water to get along with each other and form a uniform liquid. If oil and water did not get along, you would see two liquids sitting on top of each other in the bottle. When shampoo goes past its shelf life, you can see the oil and water phases start to separate. Surfactants can be responsible for a number of functions like wetting, emulsifying, foam boosting and anti-foaming, dispersing and cleansing.

In shampoo, the primary surfactant or surfactants are categorized as detergents. These detergents are responsible for shampoo’s primary function- cleaning! Secondary surfactants are typically categorized as foaming agents, which boost the lather effect of your shampoo. Foam boosting agents aren’t just for show though! The foaming in your shampoo can help to lift the oil off of your hair and scalp to increase the cleaning effect. However, the lather capability of a shampoo is not directly proportional to its effectiveness. A myth we will talk about in a later blog post if you’re interested.


Conditioners, well, condition the hair. Yes, it is that obvious. However, some conditioners are more effective for hair, whereas other conditioners are more effective for skin. In a shampoo, it’s important to have a conditioner for hair and skin, because a well-conditioned scalp can help to prevent dandruff and reduce irritation that may be associated with the surfactants in a shampoo. Conditioners are also responsible for properties of a shampoo like “smoothing” “shine” & “moisturizing.”

Thickening Agents

Thickening agents do just what they sound like too, they make your shampoo more manageable to pour out of the bottle by increasing the viscosity of your shampoo. Not much more to add here.

Chelating Agents

Recently there has been an increase of chelating shampoos on the market, however this ingredient exists in all shampoos. Chelating shampoos are simply shampoos with an increased level of the chelating agent. Chelating agents are responsible for removing build up in your hair by forming multiple bonds to a metal ion. Here is what is really going on. Where clarifying shampoos typically remove build-up in a physical way, chelating agents remove build-up in a chemical way. For example, chelating agents can remove minerals from hard water that have built up in your hair that can effect the color of your hair. In a standard shampoo formulation, chelating agents allow shampoo to function as normal in hard water. Chelating agents can be irritating and over-drying, so their content in shampoo is low, but plays a necessary role. This is also why the shampoo marketed for the chelating power should not be used regularly!


Fragrance. It’s arguably the first feature that is noticed when opening a bottle of shampoo. Fragrance gives a great sensorial effect- if you like the scent that is. Here is a fact you may not know, the term “fragrance” can be over 3100 different chemicals in the US as regulated by the Food & Drug Administration (FDA).


Lastly, preservatives. Preservatives do as they sound, they preserve the product in its manufactured state. One of the reasons products can go past their shelf life is because the preservative is no longer effective and the product can grow microorganisms such as mold, yeast, and/or bacteria. There has been a lot of controversy around certain preservatives, the most common being parabens. Parabens were a very popular preservative for a long time, because they are known as a broad spectrum preservative, which is effective against mold, yeast and bacteria. To replace parabens, multiple preservatives may need to be used. Are preservatives necessary? In a liquid shampoo where 80% of the product is water, I would have to argue it is. Water sitting in a bottle over a period of a couple of years will grow some unwanted microorganisms. The use of preservatives should be based on risk and for a liquid shampoo, is necessary.

So, that’s shampoo! We will touch more on certain general ingredient categories and specific ingredients in future posts. Let us know what you’re most interested in by submitting a request via our form!

Talk soon.


Read the Details:

Parabens in Cosmetics

Surface Active Agents (Surfactants)

Then and Now: Shampoo Formulations through the Years