The characteristics of a good shampoo are fairly obvious. A shampoo should clean away the oil and dirt, rinse out easily, and leave our hair shiny, manageable, and flexible. If we believe shampoo commercials, the right shampoo will also have good-looking strangers taking notice of our fabulous hair -- but let's not get carried away. Let's try for a goal that's more achievable -- clean, manageable hair.
First, the basics. To get oil out of our hair, we need to use soap or detergent. We know the old saying "oil and water don't mix." Oil and grease don't stick to water, which is why oil floats on water rather than mixing in. So washing our hair with water alone doesn't get out the oil and grease. Detergent and soap molecules have a dual nature: one end sticks to grease; the other end sticks to water. When we wash our hair with detergent or soap, the grease sticks to the detergent or soap and washes away with the water.
An informal survey of shampoo ingredients by looking at the labels of a couple of dozen shampoos in the supermarket shows, which the first ingredient listed after water was some kind of detergent. Since ingredients are listed in order of concentration that means there is more detergent in shampoo than anything else except water.
Wrong. According to the cosmetic chemists, detergent is actually better for our hair than soap. Soap solutions are alkaline, which makes the cuticle cells swell up and get rougher. That leaves hair dull looking. In addition, soap may leave behind deposits of calcium and magnesium (known as soap scum), which will also make the hair dull. Old-fashioned beauty books suggested completing our shampoo with a lemon juice or vinegar rinse. Acid helps dissolve soap scum and makes the cuticle scales lie flat, protecting the cortex and making our hair shiny and smooth. Most shampoos and conditioners are slightly acidic, for the same reason.
Take a look (below) at the ingredients listed on a bottle of shampoo. Some of those ingredients are coloring, fragrance, thickeners, glycol distearate (which gives shampoo an opalescent look), and lather enhancers (which help it foam). More lather doesn't necessarily mean that a shampoo is cleaning our hair any better, but most peoples equate foam with cleaning power -- so shampoo makers add lather builders to make shampoos that lather really well. And some of those ingredients condition our hair to make it more manageable.
| Agent | Acts |
|---|
| Water: | Acts as a solvent, keeping the other ingredients in solution
|
Ammonium lauryl sulfate,
Ammonium laureth sulfate: | Detergents that remove oils and grease from hair
|
| Dimethicone: | Conditioning ingredient that makes dry hair soft
|
| Glycol distearate: | Gives shampoo a pearlescent look
|
| Ammonium xylenesulfonate: | Thickener
|
| Cocamide mea: | Lather builder Hydrolyzed collagen
|
| Tricetylmonium chloride: | Conditioning ingredients that help control static and make hair easier to comb
|
| Octyl salicylate: | Sunscreen
|
| Xanthan gum: | Thickener
Cetyl alcohol,
|
| Stearyl alcohol: | Thickeners and fatty acids
|
| Disodium edta: | Preservative
|
| Sodium chloride: | Thickener
|
| Methylchloroisothiazolinone: | Fragrance
|
| Methylisothiazolinone: | Preservative
|
| Sodium citrate: | Thickener
|
| Citric acid: | Makes shampoo acidic
|
