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An
introduction to shampoos
Did you know that the word Shampoo comes form India? Well now
you do. It is a Hindi word that means to "milk" the hair - to
smooth the
hair from root to tip - and this is the best method of washing
hair (never scrub your hair). All shampoos are basically water
and detergent mixtures.
There may be various other ingredients such as herbal extracts,
proteins, fats, and conditioners, but in essence for shampoo
to work you
just need a diluted detergent. This loosens the dirt and grease
from the hair, emulsifies the oils, and allows rinsing with water
to wash the oil and dirt away.
When looking for a suitable shampoo the most important thing
you need to know is the concentration and the harshness of the
detergent
in it. The problem is there is no way for the average consumer
to find that out. Shampoos may contain anything between 1 and
25 percent
detergent. It may be exactly the same detergent, sodium lauryl
sulfate based detergents are the most common, but the concentration
will
vary considerably from brand to brand and even within a manufacturers'
product range. Cost of the shampoo is rarely an indicator of
detergent
concentration or quality. Cheap shampoos may contain a high detergent
concentration while expensive shampoos may contain very little
of
a cheap detergent. Cost is mostly about branding and the market
the manufacturer is trying to sell the product to. Some indicators
that you might think would be a rough guide to detergent power,
such as products labeled for oily hair, in fact bear no
relation to
the
amount of
the detergent in them. Shampoos for oily hair can have exactly
the same detergent at the same concentration as shampoos for
dry hair.
The difference is more likely to be a reduced amount of oil or
conditioning agent in the shampoo for oily hair, or the difference
may even just
be the packaging. The thickness of the shampoo is also not an
indicator of detergent concentration. There are many thickening
agents that
can be used that contribute nothing to the actual cleaning action
of shampoo.
 Because
the detergent concentration is not on the label, your only practical
option is to find the right shampoo, with the right detergent
concentration
for you, through trial and error. Select a few shampoos you like
the sound of and do a home comparison test. You may find you
need
up to three times the amount of one shampoo compared to another
to get the same result. Just pick the one you like the feel of
at
the price you are willing to pay. Do not be swayed on buying a
shampoo for the additional ingredients like herbal extracts.
Frankly these
will not do much, usually the amount of extract in the shampoo
is quite low and most of it is washed down the drain anyway.
When looking for a shampoo that is right for you keep in mind the
criteria below:
- It should be simple to apply, although it is worth noting
that the all in one shampoo and conditioners are usually not
as good as a separate
shampoo
and
subsequent
conditioner. Although it is more hassle, a separate shampoo
and conditioner usually gives better results.
- The shampoo should cleanse the scalp thoroughly with one application
unless you have very oily or dirty hair. Even so, you should
not
need to wash your hair more than twice.
- The hair should be left soft, shiny and easy to brush and comb.
This quality has much to do with conditioning agents. Most modern
shampoos contain them, but you may need a separate conditioner
too.
- The shampoo should rinse away easily and not leave any residue.
In a hard water area (water that has a lot of minerals dissolved
in it is called hard water) there is a greater chance of residue
being left on the hair. An acid rinse can get rid of this. People
often use lemon juice but vinegar can work just as well. Use
conditioner after an acid rinse.
- The shampoo should not be irritating to scalp skin. With the
popular fad of including herbal extracts in shampoos so dermatologists
have seen an increase in scalp dermatitis complaints. If your
shampoo irritates your scalp skin, find one without herbs in
it. If that
doesn't work, the detergent in the shampoo may be the problem.
If so, find a shampoo with a different detergent in it. Some
common shapoo detergents, like sodium lauryl sulfate, can be
irritating to sensitive skin.
- Finally, the shampoo must satisfy your tastes in color, perfume,
texture and later. None of these are really necessary for thorough
cleansing and it is all down to personal preference. Not even
lather is necessary, you can clean hair just fine without any
bubbles. We have been conditioned to believe a good lather is
important for good cleaning, but this is actually not true. Many
shampoos contain specific ingredients that make a lather, but
they do not actually contribute to the cleaning process.
Soap
versus detergent shampoos
Detergent
based shampoos are by far the most common shampoo in the supermarket
today. Detergent shampoos are a relatively recent development only
really becoming widely available from the 1950s onwards and it took
20 years for detergent shampoos to become the dominant shampoo product.
Before this time soap based shampoos were prevalent. Soap shampoos
are made from organic sources, most frequently from coconut oil
and less commonly from olive oil or palm oil. Detergents are synthetic
cleaning agents made by a chemical reaction. Detergents do a better
cleaning job and are less likely to react with minerals and salts
in the water supply compared to soap based shampoos. However, soap
shampoos are making a limited comeback as some people want to go
the organic route. There is no real problem with using a soap shampoo
except that if you live in a hard water area you may find a scum
builds up on the hair making it look dull and dry. An organic acid
rinse can get rid of this.
Waterless
shampoos
When an individual is an invalid and bed ridden waterless shampoos
can be very useful. The shampoos are usually a combination of
an
absorbent powdered substance and a mild alkali. They usually come
packaged as a straight powder, but sometimes you can get them
in
a foam or spray formulation. Either way, the principle of application
is the same. The powder is applied to the hair and this absorbs
oils (sucks the oil inside the powdered particles) and adsorbs
dirt (dirt binds to the surface of the powdered particles). The
powder
is then brushed or toweled away. These waterless shampoos work
quite well, but they are not as effective compared to water and
detergent
shampoos. For really dirty hair, the powderless shampoos may
need to be reapplied several times before getting reasonably
clean hair.
Some people who like to go completely organic prefer to make their
own powderless shampoos. You can use powdered corn starch as a dry
shampoo with a reasonable level of success. Indigenous peoples may
use chalk powder or camp fire ash as a waterless shampoo.
Shampoos
and pH
A few television commercials have made claims that their shampoos
have an acidic pH and this is superior to other shampoos. So here
are a few comments on pH and shampoo.
First just to review what pH means. Water molecules (H2O) occasionally
break apart into H+ and OH- (and H+ and OH- will join back together
to form H2O). Things dissolved in water can release or take up either
H+ or OH-, thus changing the ratio of H+ and OH- in the water. An
acidic solution (pH < 7) has more H+ than OH- , and a basic or
alkaline solution (pH > 7) has more OH- than H+. A neutral pH
is pH 7.
Hair is made from keratins. Keratin is a protein, and proteins
are chains of amino acids. Different types of protein contain different
amino acids, linked together in a different order. Keratin happens
to contain lots of the amino acid cysteine, which contains a sulfur
atom. The sulfur atoms from two cysteines join together, forming
a disulfide bond. These disulfide bonds give hair fiber its strength.
However, OH- can split disulfide bonds, thereby removing crosslinks
between keratin molecules and weakening the hair. H+ does not disrupt
disulfide bonds. As such, alkali solutions can weaken hair and strong
alkali solutions will actually dissolve it. In contrast, acid solutions
do not interact with disulfide bonds.
Most shampoos are somewhat acidic. Shampoos typically have a
pH of 4-6. Some go as low as pH 3. These are usually strong shampoos
for heavy duty cleaning. If your water supply contains a lot of
lime and other minerals dissolved in it, your water pH is most
likely
to be neutral to slightly alkali. The alkalinity of the water
is not enough to significantly weaken the hair but alkali solutions
can make the the hair cuticle open up. The outer hair cuticle
is made up of overlapping, flattened, dead cells - like tiles.
These
tiles can flake up and expose the underlying, softer cortex of
the hair fiber which is more prone to damage by environmental
chemicals.
The shampoo acidity can help with closing the cuticle of the hair.
In addition, slight acidity helps to break up soap scum and wash
it away. So in general, an acid pH shampoo is good for maintaining
the hair structure and it can neutralize adverse alkali action
on the
hair.
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