Yesterday we took a look at how to formulate a shampoo. Today, we'll take a look at the other ingredients you might add to a shampoo to take it from good to great.
In general, a shampoo contains surfactants, water, preservative, and thickener. Each one is a pretty obvious inclusion - the surfactants clean, the water thins the mixture, the preservative preserves, and the thickener thickens, but a shampoo is about more than just cleaning your hair. We want something that is bubbly and foamy, something that makes our hair feel and smell nice, and something conditioning. So let's take a look at the other ingredients you might include in a shampoo!
A little more on thickeners: From an aesthetic point of view, we need to include these to make the mixture more viscous, which imparts a nicer feeling than pouring something like water on your hands that you have to work hard get into your hair. Plus, most of the thickeners we use will make the surfactant mixture less irritating, which is always a bonus.
Cationic polymers: Conditioning agents like polyquat 7, honeyquat, and Celquat H-100 are water soluble and intended for surfactant mixes. We use up to 5% of these ingredients to leave our hair feeling conditioned. Some people can even use up to 5% as a 2-in-1 shampoo type product - but those people probably have short, virgin hair in good condition! (Celquat H-100 can create quite a gel at 0.5%, so you don't want to use it over 1%!)
Silicones: We can use dimethicone in our shampoos to increase the feeling of conditioning. You can use water soluble or oil soluble dimethicone at about 2%. (You don't need to add an emulsifier if you're using it around 2% as most detergents are good solubilizers!)
Film formers: We can add lovely hydrolyzed proteins like Cromoist (oat) or Phytokeratin to create a film over your hair strands, which will decrease the friction. You can use p...