Skin Creams

 

In cosmetics, creams signify a solid or semisolid emulsion. If an emulsion has a viscosity which allows for pouring, due to gravity, then it is not a cream. However, creams and lotions will be dealt with together as skin creams.

Ingredients and types of creams are numerous that no comprehensive books can contain all details. In addition, new products and ingredients are being introduced on daily basis.

 

Classification of Skin Creams

 

Traditionally, creams are classified according to their function, some cream types are listed below:

  1. Cleansing creams: they are oily in nature due to medium to high oil content
  2. Cold creams: can be either o/w or w/o emulsions which are difficult to rub-in. Both cleansing and cold creams contain surfactants to improve penetration and suspension properties.
  3. Moisturizing creams: These are characterized by low oil content and ease of spreading and rub-in. Usually contain emollients and moisturizing ingredients.
  4. Vanishing creams: These are composed of a low slip-point oil phase and are neutral or slightly acidic and may contain emollients and special moisturizing agents.
  5. Protective creams: Usually of low to medium oil content and are easily spreadable. They may have a slightly alkaline or acidic properties and contain protective oils like silicones and lanolin.
  6. All-purpose cream: Medium oil content which can be an o/w or a w/o emulsion but very often slightly oily. They are easily spreadable.

 

The cosmetic chemist should observe the following in any cream formulation:

  1. Volume ratio of oil to water.
  2. The nature of the continuous phase.
  3. The pH of the emulsion.
  4. The type of the emollients used.
  5. The slip-point of the oil phase.

 

Cleansing Creams

 

To ensure a healthy and good looking skin, one should remove:

  1. Grime
  2. Sebum and other secretions
  3. Dead cells
  4. Crusts
  5. Applied makeup

 

Water is an excellent and cheap cleansing agent but unfortunately very weak on oils. Therefore, soaps and detergents are added to water to improve its cleansing properties. However, the use of such cleanser is convenient in bath rooms or similar places. In addition, too much oil can be removed from the skin surface leaving it dry and rough and when alkaline soaps are used outermost cells may separate from their neighbors.

 

Properties of a good cleansing cream

 

  1. Water and oil based with medium to high oil content
  2. Unable to completely degrease the skin
  3. Leave a thin film of emollient oil
  4. Easily spreadable
  5. Should not rub-in
  6. Should not irritate the skin

 

Traditionally, cleansing creams were composed of beeswax and olive oil. Both have characteristic odor which should be masked. Therefore, in the twentieth century, mineral oil substituted olive oil. In addition, borax was found to have a positive effect on the characteristics of creams as borax reacts with the free fatty acids from wax forms soaps in situ.

Although beeswax is still used in many preparations, it has two disadvantages:

  1. It has a characteristic odor which should be masked
  2. Its price and quality are variable throughout the year and location

 

Borax is usually mixed with the molten wax where the sodium salts of the free fatty acids will be formed at the oil/water interface. The amount of borax added is about 5-6% of the mass of the wax. This means that only part of the free fatth acids will be converted to soaps. However, this ratio was found to result in better cream formulations.

 

Examples of cleansing cream formulations

 

Ingredient

1

2

3

Beeswax

5

16

12

Mineral oil

45

50

-

Borax (Na2B4O7)

0.2

0.8

0.5

Monocrystalline wax

7

-

-

Spermaceti*

-

-

12.5

Sesame oil

-

-

40

Paraffin wax

10

-

-

Water

32.8

33.2

35

Perfume, preservative

Qs

Qs

Qs

 

*Spermaceti is the semiliquid, waxy substance found in the head of the Sperm Whale, this is extracted from whale oil by crystallisation at 6 °C

 

Bentones (A clay formed by the decomposition of volcanic ash, having the ability to absorb large quantities of water and to expand to several times its normal volume) are used as alternatives to waxes as thickeners for oil phase.

 

Preparation of Creams

 

  1. The oil phase is heated to 75 oC until melting occurs
  2. Borax is dissolved in water and heated to 75 oC
  3. The aqueous phase is slowly added to the oil phase with continued stirring until the temperature reaches 45 oC where the perfume is added.

 

Improving the Efficiency of Cleansing Creams

 

Nonionic surfactants can be used to increase the efficiency of the beeswax/borax emulsions and usually results in more stable preparations. The most widely used nonionic surfactant is the sorbitan fatty acid esters.


Sorbitan monostearate

 

Examples of formulations that use nonionic surfactants:

 

Ingredient

1

2

Beeswax

10

10

Mineral oil

50

20

Lanolin

3.1

3.0

Borax

0.7

0.7

Hydrogenated vegetable oil

-

25

Antioxidant

-

0.5

Sorbitan sesquioleate

1

-

Sorbitan stearate (an emulsifier, a thickener and a stabilizer of essential oils in lotion products)

-

5.0

*Polysorbate 60 (Polyoxyethylene (20) Sorbitan Monostearate)

-

2.0

Water

35.2

33.8

Perfume

Qs

Qs

Preservative

Qs

Qs

 

*A viscous, oily, water-soluble emulsifier enabling water & oil to mix. Used to stabilize cream preparations and act as a modifier and stabilizer of shampoos.

 

Cellulose derivatives are sometimes used in order to thicken oil in water emulsions as in the following formulation:

 

Ingredient

%

Beeswax

8.0

Mineral oil

49

Paraffin wax

7.0

Cetyl alcohol

1.0

PEG 15 cocamine

1.0

Borax

0.4

Cellulose derivative (thickener)

0.2

water

33.4

 

Beeswax derivatives have also been used as o/w emulsions. The following two formulations are commercially available:

 

Ingredients

1

2

Mineral oil

50

50

Beeswax

-

7

PEG-8 sorbitan beeswax

12

-

PEG-20 sorbitan beeswax

3

8

Polysorbate 40

-

2

Perfume, preservatives

Qs

Qs

water

35

33

 

Cold Creams

 

Lighter creams of the o/w type are also available. The following 5 formulations are examples of such creams (formulations 1 & 2 are good wash creams):

 

Ingredients

1

2

3

4

5

Mineral oil

30

29

18

10

-

Stearic acid

10

13.5

-

3

4

Triethanolamine

2

1.8

-

1.8

1

Glyceryl stearate

-

-

15

-

-

Carboxymethyl cellulose

0.5

-

-

-

-

Water

57

52

55

85

66

Glycerin

-

2

5

-

1

Sodium alginate

-

1.8

-

-

-

Cety lalcohol

-

-

2

0.5

-

Spermaceti

-

-

5

-

-

*Squalene

-

-

-

-

28

Perfume

Qs

Qs

Qs

Qs

Qs

preservative

Qs

Qs

Qs

Qs

Qs

*Squalene (an oil free moisturizer) is a natural organic compound originally obtained for commercial purposes primarily from shark liver oil, though there are botanic sources as well, including rice bran, wheat germ, and olives. All higher organisms produce squalene, including humans. It is a hydrocarbon and a triterpene. The structure of squalene is shown below:

 

Acidity of the Skin

 

Since the discovery of the acidic nature of the skin, creams were made buffered slightly acidic. Also, washability was observed to improve when the sodium salt of cetylsulfate was used. The cetyl derivative was found to be better than lauryl due to its higher emulsification ability, less foam, as well as lower irritation.

 

 

An example of such a formulation is listed below:

 

Ingredient

%

Sorbitan sesquioleate

8

Ozokerite wax*

30

Petrolatum**

4

Mineral oil

10

Lanolin

12

Water

30

Lemon juice

6

Perfume, preservative

Qs

 

*is a waxy mineral that is a mixture of hydrocarbons and occurs in association with petroleum or coal. Its melting point from 58 to 100 °C. It is soluble in ether, petroleum, benzene, turpentine, chloroform, carbon disulfide, &c. Galician ozokerite varies in color from light yellow to dark brown, and frequently appears green owing to dichroism. It usually melts at 62 °C. Chemically, ozokerite consists of a mixture of various hydrocarbons, containing 85-7% by weight of carbon and 14-3% of hydrogen.

** A smooth, semisolid blend of mineral oil with waxes crystallized from the residual type of petroleum lubricating oil; the wax molecules contain 30-70 carbon atoms and are straight chains with a few branches or naphthalene rings; used as a lubricant, as a carrier in polishes and cosmetics, and as a rust preventive.

 

Good washability creams also find good markets. Example formulations are listed below:

 

Ingredient

1

2

Mineral oil

40

52

Ozokerite wax

3

-

Cetyl alcohol

2

3

Sodium cetyl sulfate

1

3

Water

54

23

Beeswax

-

5.6

Paraffin wax

-

5

Petrolatum

-

8.4

Perfume, preservative

Qs

Qs

 

Some other formulations may contain vitamins especially A, B, D, and F. Vitamin C is usually added as an antioxidant.

 

Moisturizing and Vanishing Creams

 

Moisturizing creams are most widely used in order to attain a soft and smooth skin. Vanishing creams are characterized by their ease of spreading and rapid disappearance.

 

Types of Dry Skin

 

Normally, three types of dry skin can be identified:

  1. Dryness is due to prolonged exposure to low humidity which modify the normal hydration gradient of the skin.
  2. Dryness can be caused through physical or chemical factors leading to continual degreasing.
  3. Dryness of skin due to aging, which is primarily due to UV exposure.

 

Strategies to restoring water to dry skin:

  1. Use of humectants
  2. Occlusive approaches (like gloves, lanolin, mineral or vegetable oil)
  3. Use of artificial skin lipid mixtures

 

Most recently, quaternium substances of cellulose and gluconic acid (quaternary ammonium complexes) have been found to act as skin barrier materials that not only behave as moisturizers but also as skin conditioners.

 

Examples of formulations using quaternium substances are listed below:

 

Ingredient

%

Isopropyl linoleate*

2

Glyceryl stearate*

3

Diisopropyladipate*

2

Myristyl myristate*

1

PEG-40 stearate*

1

Cetyl alcohol

1.5

Quaternium 22

2

Hydroxyethyl cellulose (2%)

25

Propylene glycol

3

Water

59

Perfume, preservative

Qs

 

* alkyl esters are used as emollients

 

A formulation of a simple vanishing cream is shown below:

 

Ingredient

%

Stearic acid

15

KOH

0.7

Glycerin

8

Water

76

Perfume, preservative

Qs

 

 

Hand Creams

 

Hands are usually subjected to severe environmental conditions like soaps, and hot detergents, among many others. These materials solubilize lipids and damage cell walls. Hands will become dry and flaky which is referred to as dishpan hands. Hand creams are supposed to remedy this problem and mosturize the skin as well. In this respects, lotions are preferred over solid creams.

Hand Dermatitis

The hands of some people are sensitive to normal daily activities and easily become dry, cracked, and scaly.  Water, soap, detergents, and cleansers are the most common reasons in triggering this problem, which occurs in housewives, nurses, cooks, beauticians, waiters and others whose hands are repeatedly wetted.  The rash caused by these exposures is a mild to severe irritation, not an allergy. 

Blistering rashes may occur on the hands.  They may look like dishpan hands, and are irritated and worsened by water and cleanser exposure.  The treatment of these ‘hand eczemas' of whatever cause is the same.

      Prevention of Further Irritation

1. Decrease exposure to water and cleansers as much as possible.  This might mean asking another household member to do some of these chores, or being temporarily transferred to another sort of job at work.  Frequency of wetting and drying is more important than the duration of wetting, so washing one large load of dishes a day is better than doing several small ones during the day.  If you can use tongs and long-handled brushes when practical, this decreases water exposure.  Unfortunately, rubber or plastic household gloves are not of great benefit in protecting you from common household exposures because it is the wetting which is most damaging, and gloves trap sweat and make the hand completely wet after a few minutes of wearing. Avoiding wetting is much more effective than trying to protect against wetting. 

2. Lubricating the skin is important to replace natural skin oils leached out by wetting.  You should stop using all commercial hand lotions and moisturizing creams and use only the products your doctor recommends, because many of the commercial products contain fragrances and other chemicals which are irritants.  Plain greases, such as mineral oil or Vaseline, are the safest.  These should be rubbed in thinly very often:  after every water exposure, and whenever the skin feels dry.  This may require applications as often as 10 times a day, especially at the beginning, but overlubrication is impossible, and underlubrication is harmful. 

3. Treatment of the inflamed skin itself is by cortisone creams.  Potent ones are usually necessary because penetration through thick skin is poor.  The cortisone cream or ointment is applied thinly two or three times a day, especially after water exposure.  If the cream alone does not suppress redness and itching, then a much greater effect can be obtained by covering the cream with a disposable plastic glove. 

  This ‘occlusion' greatly increases penetration of the medication, and softens and humidifies dry skin.  After wearing the gloves overnight, for a few hours, or as long as possible, the hands should be rinsed and a cortisone cream or lubricant applied to prevent drying.  If only the palms of the hand have a rash, then the glove fingers can be cut off to make wearing the glove more comfortable. 

After the rash has improved, or is under control, a mild cortisone cream is used instead of the potent one.  Prolonged use of potent cortisone creams, especially under plastic gloves, may cause thinning of the skin.  Lubricants alone will suffice if the rash has resolved, and cortisone creams can be used again if a relapse occurs. 

If the hand inflammation does not respond to external therapy, then your doctor may recommend cortisone pills or shots.  These usually improve the rash but may have internal side effects, and the rash may reappear when they are stopped, so they are used with caution for only short periods. 

 Examples of such lotions are listed below:

 

Example 1:

Ingredient

%

Glyceryl stearate

2.7

Cetyl alcohol

1.5

Dimethicone

1.5

Lanolin oil

2

Squalene

3

Sodium lauryl sulfate

0.3

Water

T0 100

Perfume, preservative

Qs

 

Example 2:

Ingredient

%

Stearic acid

7

Lanolin

0.5

Sorbitan oleate

0.5

Sorbitol*

10

Water

To 100

Perfume, preservative

Qs

* A white, sweetish material, C6H8(OH)6, found in various berries and fruits or prepared synthetically and used as a flavoring agent, a sugar substitute and a moisturizer in cosmetics and other products.

 

Example 3:

Ingredient

%

CTAB

1.5

Cetyl alcohol

2.5

glycerin

8

Lanolin oil

2

Isopropyl myristate

3

Water

T0 100

Perfume, preservative

Qs

 

All Purpose Creams

 

As mentioned earlier, these creams are characterized by medium oil content and can be formulated to be easily spreadable. Examples are shown below:

Example 1:

Ingredient

%

Trioleate phosphate

3

Petrolatum

18

Glyceryl stearate

5

Isopropyl palmitate

4

Cetyl alcohol

2

Stearyl heptanoate

0.5

Stearyl octanoate

0.5

Sorbitol

5

Water

T0 100

Perfume, preservative

Qs

 

Example 2 and 3:

Ingredients

1

2

Stearic acid

15

15

Beeswax

2

2

Lanolin

4

2

Mineral oil

23

34

Polysorbate 85

1

-

Sorbitol trioleate

1

-

PEG-40 stearate

-

5

Sorbitol

12

10

Water

T0 100

T0 100

Perfume, preservative

Qs

Qs

 

See also the following information from the literature on facial creams:

 

FORMULATIONS BASICS: FACIAL CREAM

Before starting...

Facial care creams formulations include many kinds of formulations, depending on the nature of the skin or on the desired effects. Either protection against pollution and oxidation is needed or anti-wrinkle activity. Actives may also be added in order to correct an oily/ greasy skin, a dry or a sensitive skin.. Many formulations are basically Oil in Water emulsions or Water in Oil emulsions. The typical skin care emulsion is now more likely to be o/w than w/o. Technology has advanced to the point where w/o stable emulsions can be prepared at room temperature.

Required qualities :

*       Neutral or pleasant odor and color

*       Easy to spread, pleasant feeling during application

*       Easy penetration

*       Non-oily/ non-greasy after application

*       Non comedogenic

*       Well tolerance/ non-allergenic

*       Bring hydration

 

 Typical Ingredients

 

 Usual Method

Must Use

 

Emulsifiers

2-6%

Emollients

10-35 %

Thickener

0.1-1%

Deionized Water

Q.S.


Usual

 

Preservatives

0.2-1 %

Humectants

1-8 %

Consistency factors

1-6%

Antioxidants

0.01-0.05%

UV filters

0.01-0.5%


Optional

 

Chelating Agents

0-0.02 %

Fragrance

0.1-1 %

Active agents

0.1-2%

Colouring agents

Q.S.

Aesthetic enhancers

0.1-5%

Aqueous phase: Thickener is dispersed in cold or warm water at 75-80°C (depending on the recommandations of the producer) under intensive stirring, until a homogeneous gel is formed. This first phase is combined with the oily phase (Lipophilic components : emulsifiers + emollients + consistency factors) that has also been melted and heated to the same temperature. Mix under intensive stirring until emulsion is formed. Then mix gently while emulsion is being cooled. Sensitive components like actives, special additives and preservatives are added after the mixture has been cooled (40-30°C) to keep their properties intact.

 

 

Tips

How to vary the consistency of your cream?

- Changing the % of the oily phase allows variations in the final viscosity of your preparation. For Oil in Water emulsion the greater the oily phase the higher the viscosity. Inversely for Water in Oil or Water in Silicone emulsion : the greater the aqueous phase the higher the viscosity.

- Vary the % of thickeners (gelling agents or consistency agents like waxes). However some stabilizers can prevent settling without increasing the viscosity.

 

 

Sample Recipe : "Vanishing cream"

Ingredients

Method

Composition

Function

% (w/w)


Phase A

Glyceryl stearate

Emulsifier/ consistency agent

4.00

Stearic acid

Emulsifier/ consistency agent

16.0

Ceteareth-12*

Emulsifier

3.00

Octyldodecanol

Emollient

3.00

Paraffinum liquidum

Emollient

3.00

Phase B

Triethanolamine

pH buffer

0.50

Deionized Water

 

69.3

Phase C

Phenoxyethanol, methyl-, ethyl-, propyl-, butyl-, isopropyl paraben

Preservative

0.7

Fragrance

 

0.5

Phase A  and phase B have to be mixed and heated separately to 80°C. Add slowly B into A under intensive stirring until the emulsion is formed. Then add more quickly the rest of the phase and keep stirring during a few minutes. Continue stirring gently until the temperature is at 40°C. Then Add phase C. Keep stirring the mixture slowly while it is being cooled.

*Ceteareth-n (where n is a number) refer to polyoxyethylene ethers of a mixture of high molecular mass saturated fatty alcohols (mainly cetyl alcohol and stearyl alcohol). The number n indicates the average number of etyhlene oxide residues in the polyoxyethylene chain.

These compounds are non-ionic surfactants, fequently used as emulsifiers in cosmetics

 

 

 

Dry skin formulation

Ingredients choice criteria:

- Slow down the TEWL (Transepidermal water loss) by using occlusive emollients in the oily phase (squalane, beeswax, triglycerides, essential fatty acids, silicones..)

- Reenforce or reconstitute the NMF (Natural moisturizing factor) with adequate additives (sodium lactate, sodium PCA)

- Bring humectancy with hygroscopic components (urea, allantoin, polyols, hyaluronic acid..)

Enhance aesthetic

As indicated above, aesthetic enhancers may be added: eg- pearlescent pigments, texturing agents, soft-feeling agents like silicone elastomers.