Understanding
Emulsions and Emulsifiers (Brief Overview)
An
emulsion is a mixture of water based and oil based ingredients that
are bonded together by an emulsifier.
An
emulsifier is a substance or combination of substances that create
the emulsion bond.
Types
of Emulsions
Water
in Oil W/O - in this type of emulsion the oil surrounds the water and
the oil touches the skin first. The level of greasiness depends on
the percent of oil vs water in the formula and how much is absorbed
into the skin. An W/O emulsion is made with a choice of oils, water
and the emulsifiers needed to make a full, stable emulsion. If done
correctly the product will have little to no greasiness.
Oil
in Water O/W - in this type of emulsion the water surrounded the oil.
This emulsion produces cream and lotions that feel moist, lighter and
less greasy. As they are absorbed into the skin there is very little
to no oily residue noted with application. A O/W emulsion needs the
correct level and type of emulsifier to create a stable and complete
emulsion.
Types
of Emulsifiers
Emulsifier
can range from vegan, organic and natural all the way to synthetic
lab created.
They
can be sourced from vegetables, animals or chemicals and there are a
multitude of both natural, mechanical and chemical extraction methods
as well.
They
can be produced or harvested in the USA or imported.
This
and much more information is necessary to allow the formulator to
determination which emulsifier is the best choice for a formulation.
The
HLB (Hydrophilic-lipophilic balance) of an emulsifier is also very
important to help determine how effective it will be for each
formulation. The higher the HLB the greater its emulsifying ability.
Beeswax
- This weak emulsifier can be naturally harvested from bees and then
filtered or it can be produced synthetically. It is used in cosmetic
and skin care products as both a thickening agent, emulsifier and
humectant. When used incorrectly in cosmetic formulations, beeswax
can be heavy, waxy and comedogenic. It also provides the positive
properties of being and emollient and softening agent to
formulations when used correctly. HLB ~ 10-12
Borax
- This Borax or sodium borate is a naturally occurring alkaline
mineral first discovered over 4000 years ago. It is found in large
quantities in the Western United States as well as in the Tibet area
of China. Borax alone will not emulsify. It must be used in
conjunction with Beeswax. Together the electricity from the friction
of the two causes the reaction and yields an emulsion. When used in
combination Beeswax/Borax is somewhat difficult to master, can be
problematic and may not provide for a stable formulation with an
acceptable shelf life for consumer sales. HLB unknown
Carbomer
- This synthetically derived cross-linked polymer of acrylic acid is
used an emulsifier, emulsion stabilizer, to adjust viscosity and as
a thickening agent. It is often used to create gel like
formulations. HLB ~ 12
Cetyl
Alcohol - This emulsifier can be synthetically created or naturally
derived from coconut or other vegetable fatty alcohol. It is an
emulsifying wax made by combining fatty alcohols. (see fatty
alcohols) It is used in many formulations as an emollient,
thickening agent, moisturizer, emulsifier, stabilizer or opacifier
as well as a carrying agent for other ingredients. It can be
extracted using chemicals or naturally mechanically extracted. HLB ~
15
Cetearyl
or Cetostearyl Alcohol (used interchangeably) - is a blend of cetyl
alcohol and stearyl alcohol usually meeting *NF specifications. HLB
~ 14-15
Emulsifying
Wax (aka E wax) - This is a generic term used for emulsifier blends
and can contain any combination of emulsifiers at whatever
proprietary ratios the manufacturer chooses. It can be organic,
natural, vegetable sourced or completely synthetic. It is usually a
white waxy solid, but can be creamy or yellow and often looks like
small dome pellets or beads. It is highly effective in both w/o and
o/w formulations. It usually has the characteristics of cetyl
alcohol combined with the viscosity building effect of stearyl
alcohol and is a very effective thickener that form extremely stable
emulsions in either w/o or o/w preparations. HLB ~ 15
Fatty
Alcohols - A fatty alcohol it is an alcohol, which is derived from a
vegetable or animal fat source. It does not behave like a 'real
alcohol' like ethanol and is not drying to the skin. Fatty alcohols
are usually derived from coconut oil or palm oil. Cetyl alcohol is
often made by heating coconut oil with a strong base like Sodium
hydroxide (Lye). This process is the same process that occurs during
soap making (saponification). The differences between cetyl, stearyl
and cetostearyl alcohol is very little. Stearyl alcohol has a
slightly longer carbon chain than cetyl alcohol. (Cetyl has 16
carbons while Stearyl has 18). Cetearyl or Cetostearyl alcohol are
simply a combination of cetyl and stearyl alcohol. HLB ~ 14 +
Lecithin
- Lecithin is a weak natural emulsifier containing phospholipids as
its major emulsifying component. It is found abundantly in animals
and plants. It can be used in both its liquid or powder form in
formulations. Lecithin is sourced from plants like soybeans, corn or
rapeseed. It can be fractionated or isolated from special components
of the raw materials or isolated from egg yolks by excluding the
phospholipids, which compose about 30% of the egg yolk. Lecithin as
an emulsifier can also be difficult to use in formulations. It does
not have strong emulsification and is often used in combination with
beeswax and borax. Because of its strong odor and dark color it
should not be used at greater than 3% of the total formulation. HLB
~ 4
PEG's
- PEG's are synthetic emulsifiers and usually contain letters and
numbers. PEG stands for polyethylene glycol and it made from
ethylene oxide. These polymers are mixed with various other
molecules to produce a wide variety of products of unique qualities.
Polyethylene glycol (PEG) is a water-soluble lubricant sourced from
petroleum and/or mineral sources. HLB ~ 15
Polysorbates
- These non-ionic surfactants and emulsifiers are derived from the
combination of fatty alcohols and sorbitol which comes from fruit
and berries. They can also be synthetically created. Polysorbates
are oily liquids and they are most often used in cosmetics to
solubilize oils into very high content water based formulations.HLB
~ 16-17
Polysorbates
are followed by a number that indicates the fatty acid associated
with the sorbitol part of the molecule.
PS
20 - sorbitan monolaurate derived from Lauric acid (often coconut and
palm oil sourced) and connected to sorbitol
PS
40 - sorbitan monopalmitate derived from Palmitic acid (often coconut
and palm oil sourced) and connected to sorbitol
PS
60 - sorbitan monostearate derived from Stearic acid (often coconut
and palm oil sourced) and connected to sorbitol
PS
80 - sorbitan monooleate derived from Oleic acid (often coconut and
palm oil sourced) and connected to sorbitol
Stearic
Acid - Stearic acid, also called Octadecanoic Acid is one of the
most common long-chain fatty acids found in its combined form of
stearic, palmitic and oleic acid in animal and vegetable fats. In
nature, stearic acid occurs primarily as a mixed triglyceride with
other long-chain acids and as an ester of a fatty alcohol. This
emulsifier can be derived from plants or created synthetically.
Usually it is derived naturally from palm and is often listed as
Palm Stearic Acid on ingredient lists. Stearic acid functions as a
moisturizing lipid and is an excellent emulsifier. At the same time
it improves the shelf life and consistency of the emulsion. Stearic
acid is also a natural thickener used for many personal care
products. HLB ~ 15
Stearyl
Alcohol - This emulsifier can be synthetically created or naturally
derived from coconut or other vegetable fatty alcohol. It is an
emulsifying wax made by combining fatty alcohols. (see fatty
alcohols) It is used in many formulations as an emollient,
thickening agent, moisturizer, emulsifier, stabilizer or opacifier
as well as a carrying agent for other ingredients. It can be
extracted using chemicals or naturally mechanically extracted. HLB ~
14
*
NF - When the ingredient name is often followed by the initials NF,
this indicates that it conforms to the specifications of the National
Formulary. These standards are used by regulatory agencies and
manufacturers to help to ensure that these products are of the
appropriate identity, as well as strength, quality, purity, and
consistency.
With
all the emusifiers on the market today, it can be very difficult to
figure out the right one(s) for your purpose(s). Finding the right
supplier of raw materials, one that shares your goals, expectations
and standards is the first step in the right direction to a natural
you.
