What is shampooIn the language of the personal care industry, companies build shampoo systems. The formulators start with the surfactants, which can be anionic, cationic, nonionic, or amphoteric--but what they all have in common is a polar hydrophilic head with at least one long-chain hydrophobic tail. Shampoos generally contain suites of surfactants that act synergistically--each has its own role, but they also work in concert to improve the overall formulation.

Some anionics commonly used in shampoos are sodium lauryl ether sulfate (also called sodium laureth sulfate), sodium lauryl sulfate, and the ammonium versions. The anionic surfactant is the primary foaming and cleansing component of a shampoo.

Olealkonium chloride, distearyldimonium chloride, and isostearyl ethyldimonium ethosulfate are cationic surfactants that are used in some shampoos. Cationics like these provide some conditioning to the hair, and they also can boost the viscosity of the shampoo formula.

Amphoterics such as cocamidopropyl betaine or cocamidopropyl hydroxysultaine provide foam stabilization and viscosity-building properties.

Nonionics such as polyethylene glycol (PEG) esters can play a number of roles in a shampoo system. For example, PEG-80 sorbitan laurate promotes mild cleansing, whereas PEG-150 distearate is used to build viscosity. Alkanolamides--one you might see listed on a label is cocamide MEA--is an example of another type of nonionic that provides foam stabilization and viscosity-building properties.

Surfactants clean hair by stripping sebum from hair shafts. Sebum is the natural oily coating that tends to collect dirt, styling products, scalp flakes, and the like. It is attracted to the hydrophobic end of the surfactant, then washed away when a shampooer rinses. Surfactants determine how gently hair will be cleaned--harsh cleaners can overstrip hair and dry skin.FORMULATORS also consider ingredients that will provide other characteristics. Glycol stearate or glycol distearate will impart pearlescence to a shampoo system; ethyl alcohol, glycerol, or sodium xylene sulfonate can be used to maintain clarity; and a small amount of a resin latex can be used if an opaque shampoo is desired. Formulators will add thickeners (cocamide monoisopropanolamide or sodium chloride or citrate, for example) and conditioners (dimethicone or quaternized cellulosic polymers) to achieve the right "feel" in the shampoo and on the cleaned hair, respectively.

Conditioners can also help with static control. Shampoo makers may add a sunscreen or a humectant--to help retain moisture--and they'll add preservatives and antioxidants. Fragrances and dyes will be incorporated. Formulators may also consider using foam stabilizers (betaines or amine oxides) or chelators to tie up trace ions that can complex with fragrance components and dyes.

And formulators have to ensure that the pH is within a workable range, some say 5.5 to 6.5. Correct pH is important because the cuticle of the hair, which is exposed after the sebum is stripped away, is covered with overlapping scales that are smoothed and soothed in a properly acidic environment. Aggravated scales don't overlap nicely, and they make hair look dull and feel rough. They can also snag other raised scales on neighboring shafts, resulting in snarls.

Getting the ingredients and proportions right is a matter of experience if formulators are using tried-and-true ingredients or trial and error if they are moving in new directions. They need to end up with a formulation that has all of the desired attributes for the consumer as well as being processible, stable, and within budget.

Formulators can tweak shampoo in a wide variety of ways, but it's up to the marketing experts to create an image for their shampoo that will make people actually look for it among all the contenders--and maybe even remember it 30 years later.



What is conditioner



When considering the question of how hair conditioner works you first need to know about the structure of hair. Hair, as you may know, is composed of a protein called keratin. This fact is important because keratin has a high percentage of those amino acids which have negative charges sticking out, like the hairs on a nettle. The next thing you need to know is that most hair conditioners contain positively charged molecules called cationic1 surfactants. Soap, shampoo, and other cleaners contain surfactants (also called detergents) that are anionic2; that is, negatively charged.

These cleaners are very effective at removing dirt, but they also remove natural oils and positive charges from the hair. The positively charged surfactants in hair conditioner are attracted to the negative charges in your hair, and do not rinse out completely with water. When the hair dries, it is coated with a thin film, which adds weight, makes the hair easier to comb, and prevents static electricity from building up and 'frizzing' the hair. Static buildup, by the way, is what happens when the positive charges are stripped from the hair. Rubber combs do this very nicely, which is why combing your hair on a dry day makes the hair 'frizz out'; because the negative charges on your hair are repelling each other! All surfactants comprise an 'oily part' and a 'watery part'. The watery part - called the hydrophile - is what sticks to the hair; it contains the positive charge.

The oily part - called the hydrophobe - is what gives the surfactant its conditioning ability, as it smooths the hair and gives it weight. The cationic surfactants used in conditioners come in several types, and can be classified by the nature of their hydrophobes. If the hydrophobe has the structure of a saturated fat, like lard or butter, the surfactant has a waxy consistency. Oily hydrophobes, with a structure like liquid vegetable oil, give the surfactant a lighter texture; they may even be liquids. Hydrophobic polymers yield a hard, plastic-like material. Hair conditioners come in several different types. 'Pack' conditioners are heavy and creamy in consistency. They contain high percentages of 'fatty' surfactants, and are used when the hair is damaged. Such conditioners are left in the hair for a long time, and will virtually 'glue' split ends and stripped scales into place. 'Leave-in' conditioners are lightweight, and will contain lighter-weight 'oily' surfactants, which add little weight to the hair.

Ordinary conditioners have a balance between the two. There are also 'hold' conditioners; which are combination products that provide the benefits of conditioning while also holding the hair in place like a mousse. This effect is achieved using cationic polymers. Finally, there are some conditioning ingredients which are not cationic. These do not offer the best results, but they have benefits of their own. Some anionic surfactants, which carry no electric charge, will stick to the hair in useful quantities. Unlike cationic surfactants, they can be mixed with anionic surfactants to produce conditioning shampoos. Other ingredients, like esters, oils, and polymers, are added to improve lustre, add comb-ability, and assure that the conditioning ingredients stay mixed in the bottle.