Shampooing should be as easy as wet, lather, rinse, repeat. But what nobody tells you is that shampoo goes on the scalp and conditioner goes on the lengths and ends.
The correct way to shampoo is to wash only the first 5 cm of the hair at the scalp where sebaceous oils, sweat and dirt gather. It really is not necessary to shampoo the lengths and ends of your hair as the shampoo that washes over the lengths and ends during rising should be sufficient to remove any dust, dirt and smog. As a matter of fact, washing your lengths and ends will only remove essential moisture and natural oils, leading to dried out ends.
Shampoo is formulated to open up the cuticles to ensure proper cleansing. Leaving those cuticles open will be disastrous as precious moisture and colour will seep from the hair. That is where conditioner comes in. Conditioner tightly closes the cuticle to prevent moisture loss, fight frizz and to help with detangling. When conditioning, you should use sufficient conditioner to cover the lengths and ends to ensure proper closure of the cuticle over the entire hair shaft.
That is also why it is important to ALWAYS use a conditioner after shampooing.
Also for this same reason, it is difficult to understand why people would want to use two-in-one shampoo’s and conditioners. Are you closing or opening the cuticle? Are you cleansing or moisturising? I am sure the hair shaft is just as confused as I am.
As a result, on long hair, you would be using more conditioner than shampoo and your conditioner would be depleted first. On short hair however, it would be a different story.
Sometimes you really do not have to wash your hair. Here is why.
Shampoos and conditioners fulfill very specific functions. Most balanced shampoos have a pH of +/- 5.5. This will ensure that the cuticle of the hair is opened to thoroughly clean the hair. The higher the pH, the more the cuticle will open.
Good conditioners have a pH around 4.5 to securely close the
cuticle after shampooing. It hydrates
the hair (i.e. replaces some of the oil that has been removed by the shampoo)
and some will film the hair to smooth the cuticle and to prevent tangles. Conditioners are VERY important and should
not be skipped, as you do not want to leave the cuticle open. That will lead to colour and moisture
loss. In other words: Dry, dull
Now water has a pH of +/- 7 – which is higher than that of a
shampoo. Hence, it would be sufficient
to “wash” your hair using only water and conditioning afterwards – i.e.
However, co-washing will not be sufficient if there is sebum on the scalp and roots or if you use any products that could possibly leave a residue that will lead to product build-up (i.e. hairspray, dry shampoo, etc.). Then you would need to use a shampoo that is both balanced and efficient.
Sebum is the oil that is produced by the sebaceous gland in
the scalp. This oil is necessary to
prevent hair from drying out, but dirt and dust accumulates on the oil, making
it a little bit more difficult to remove to dirt and dust. Hence why shampoos are formulated to contain
surfactants. A surfactant lowers the
surface tension between the sebum and the water, making it possible to wash
away the oil. Water alone (irrespective
of its pH) cannot do this.
But, if your hair is never oily, or if you use products that
are residue-free, co-washing could be a great way to save time and money. But remember – Always, always finish with a
good quality conditioner! And remember –
conditioner goes on the lengths and ends, not the scalp!
Hair masks and conditioners are formulated to have a specific
pH. Shampoo’s normally have a more
alkaline pH in order to open the cuticles.
Hair conditioners and masks have a more acidic pH to close the
cuticles. It is imperative to close the
cuticle to retain moisture, prevent tangles and prevent static.
Manufacturers use a variety of acidic substances like citric
acid, hyaluronic acids, etc. to reduce the pH of hair conditioners and
masks. However, strong acids are very dehydrating.
It is also very corrosive and will damage the protein and lipids in the
structure of the hair. The extent of the
damage will depend on:
The strength of the acid; and/or
The duration of the exposure.
Thus, the answer here lies in the instructions on the bottle. If the bottle says to rinse out after 2 minutes, then rinse it out after 2 minutes. The formulation is probably too acidic to be left on longer than the indicated time and could severely dry out and damage your hair if the hair is exposed to the conditioner or mask for longer. Only leave a product in, if it specifically declares that it is a leave-in product.