MODULE 1. “TECHNOLOGY OF COSMETIC PRODUCTS”
Content modules: 1. Technology of cosmetic creams, liquids and makeup tools
BASIC CONCEPTS AND TERMINOLOGY OF TECHNOLOGY OF PERFUME AND COSMETICS. COSMETIC SKIN CARE. SKIN STRUCTURE. LIQUID COSMETIC PRODUCT. LOTIONS. TONERS.
THE STRUCTURE AND FUNCTION OF THE SKIN
The skin is an amazing structure; it is the largest organ of the body containing many structures such as capillaries, lymphatic vessels, nerve endings, glands and more. These structures help the skin to perform its many functions which include temperature regulation, sensory and waste elimination. An average adult males skin would cover an area of between 19 and 22 sq feet and weigh between 10 and 16% of the body weight. This structure varies in thickness from 0.5mm to 4mm, the thinnest area being the eye lids which in its self serves a purpose, thicker areas of skin tend to be found where there is more friction or where palms of hands, soles of feet and thinner areas where the skieeds to be more flexible eye lids.
The Skin is broken down into 2 main Layers the epidermis (or cuticle) (fig 1,2) and the dermis (or true skin).(fig 3)
1. The epidermis is the outer layers of the skin and is divided into two zones, the horny and the germinal zone.
The horny zone is subdivided into 3 layers:
i. Stratum Corneum (fig 1,2) – The outer layer of the skin comprising of 25 to 30 rows of dead flat scaly cells (keratinocytes). These cells contain the protein keratin and between the cells are lipids (a greasy organic compound that is insoluble in water) which help to create the water proof barrier, this aids protection. These cells are replaced by the layer below as they work their way to the surface and in turn the top layer of cells are constantly being shed.
ii. Stratum Lucidum (fig 1) – A layer of 3 to 4 rows of dead flat transparent cells. This layer is only found in the palm and soles. Eleidin droplets (“A semi fluid, acidophilic substance related to keratin”) are present and give it a transparent appearance.
iii. Stratum Granulosum (fig 1,2) – A layer of 2 to 3 rows of flattened cells (keratinocytes) which contain granules of keratohyalin, this converts the tonofilaments into keratin. Tonofilaments are proteins and are part of the mechanism that helps to bind the cells together. At this stage the cells are dying.
The germinal zone is subdivided into 2 layers. These 2 layers are often classed as 1
i. Stratum Spinosum or the prickle cell layer (fig 1,2) – There are 8 to 10 rows of many sided cells[3] and have prickly bundles of fibres which tightly connect them together, hence the name.
ii. Stratum Germinativum or Basal layer (fig 1,2). A single columnar cell layer at the base of the epidermis, about 90% of these cells are Keratinocytes. Other cells found are Merkel, Langerlen and Melanocytes. Melanocytes are cells in low abundance in the epidermis that produce the pigment melanin. The pigment made in melanocytes is transferred to the cells of the hair or epidermis. The melanin granules are injected into (or ingested by) the keratinocyte cells. There, the melanin granules accumulate around the nucleus of each keratinocyte. Melanin absorbs harmful ultraviolet (UV) light before the UV radiation can reach the nucleus. Melanin protects the DNA in the nucleus from UV radiation damage. When melanin is produced and distributed properly in the skin, dividing cells are protected from mutations that might otherwise be caused by harmful UV light.
There are stem cells in this layer which divide to produce new cells. The stratum germinativum rests on a basement membrane dividing the dermis and epidermis. Tonofilaments bind the cells together and also bind them to the membrane below and stratum spinosum above.
Figure 1 Epidermis
Figure 2 Epidermis
2. The Dermis is the deeper of the two main layers and is divided into two regions
a. The Papillary region – is made up of areolar connective tissue which contain fine elastic fibres. It has dermal papillae some of which contaierve endings or capillaries and stick up into the epidermis like fingers. ( fig 3)
b. The Reticular region – this layer is an irregular dense connective tissue made up of a net like pattern of collagen and elastic fibres, this provides the skin with its strength and its ability to stretch and return to its original length. This layer is attached to the subcutaneous layer.
The dermis holds many structures, which are needed to complete the skins functions.
1. Capillary blood vessels, there is a vast network of capillaries throughout the dermis known as the blood reservoir it holds 8 to 10% of the body’s blood. Without this the skin could not complete its function of temperature regulation. The epidermis is also fed from this supply.(fig3)
2. Lymphatic vessels which carry interstitial fluid back to the blood, for elimination.(fig3)
3. Sensory nerve endings (tactile receptors) to detect hot and cold (temperature regulation), pain (protection) and other sensations felt through the skin (fig3) Meissener’s corpuscles (fig 3) which respond to gentle pressure and Pacinian corpuscles (fig3) which respond to deep pressure.
4. Sweat glands (eccrine and apocrine larger of the two glands) which help the skin to regulate temperature and eliminating impurities.(fig3)
5. Sebacous glands that produce sebum which balances the acid mantal, this is part of the protection roll.(fig3)
6. Hair to protect (eyelashes) and trap warm air to help with warming the body.(fig3)
7. Hair follicles to grow hair in.(fig3)
8. Arrector pili muscles which are attached to the hair follicle and when stimulated will make your hair stand up.(fig3)
Figure 3 skin cross section
The 7 main functions of the skin are:
1. Protection. The stratum corneum is a tightly interlocking layer of dead cells that guard against infections entering via the skin. It is also mostly waterproof (see function 4) preventing the loss or entry of fluids. The acidic ph balance inhibits the growth of bacteria. It protects against mechanical damage such as abrasions and friction. It tries to protect against the damaging effects of sunlight (ultraviolet light), through the regulation of melanin which is produced by the Melanocyte cells. When stimulated by sunlight the cells produce more melanin which appears as a sun tan, this is the skins way of trying to protect its self.
2. Heat regulation. Body temperature is controlled by sensing the environmental temperature via the nerve endings and then adjusting the blood flow and sweat production accordingly to try and maintain the body’s optimal working temperature which is around 37 degrees C. It does this by producing more sweat from the sweat glands which evaporates and cools and by blood vessel dilation to reduce temperature and visa versa to increase body temperature.
3. Sensation. With most sensory nerve endings terminating in the dermis, the skin is able to sense many things including, environmental temperature, pressure, vibrations, touch and pain and then reacts accordingly.(fig3)
4. Absorption. Although the skin is almost waterproof some lipid soluble materials will penetrate. Included in this list are fat soluble vitamins, oxygen, carbon dioxide, also some drugs and unfortunately toxic materials.
5. Secretion. Sebum is secreted from sebaceous glands; the sebum balances the skins acid mantle. Sebum makes the skin oily when there is an over production. It moisturises the skin keeping it soft and supple therefore prevents cracks and openings in the skin.
6. Elimination. Small amounts of urea, uric acid, ammonia and lactic acid are excreted out of the body in our sweat which is produced by the sweat glands.
7. Vitamin D formation. The skin with the aid of UVB (ultraviolet) a part of sunlight, forms vitamin D. The UV light converts a fatty substance called Ergosterol (colourless, crystalline, water-insoluble sterol, C28H43OH, that occurs in ergot and yeast) into vitamin D which then circulates around the body and is used in the formation and maintenance of bone along with calcium and phosphorous.
The skin is the largest human organ. It covers between 1.5 and 2 m2 , comprising about one sixth of total body weight.
Function of Skin
The skin performs a complex role in human physiology:
§ serves as a barrier to the environment, and some glands (sebaceous) may have weak anti-infective properties.
§ acts as a channel for communication to the outside world.
§ protects us from water loss, friction wounds, and impact wounds.
§ uses specialized pigment cells to protect us from ultraviolet rays of the sun.
§ produces vitamin D in the epidermal layer, when it is exposed to the sun’s rays.
§ helps regulate body temperature through sweat glands.
§ helps regulate metabolism.
§ has esthetic and beauty qualities.
The skin consists of three functional layers:
– Epidermis
– Dermis or corium
– Subcutis (hypodermis)
In these layers are found the epidermal appendages: nails, hair and glands. (Note: Sebaceous and sweat glands belong to the exocrine glands. Sebaceous glands are nearly always connected to hair follicles. Sweat glands deliver their secretions directly to the skin surface.) The skin performs various functions such as temperature regulation and insulation, energy storage, sensory perception and protection from environmental influences such as fungi, bacteria and (UV) radiation.
The skin is composed of several layers. The lowest layer is called the dermis. This layer is composed of connective tissue, blood vessels, nerve endings, hair follicles, and sweat and oil glands. (1-Epidermis; 2-Dermis;3-Subcutis;4-Hair follicle;5-Sebaceous gland;6-Sweat gland)
Skin Cell Types
Keratinocytes
The most abundant cell type of the epidermis is the keratinocyte. These cells produce keratin proteins that provide some of the rigidity of the outer layers of the skin. Keratinocytes also form the bulk of the material in hair follicles. Dandruff and hair are dead keratinocytes.
Fibroblasts
The dermis is produced largely by fibroblasts, which during embryonic development are part of the mesenchyme. The fibroblasts produce the collagens and elastins that make skin very durable, from within.
Melanocytes
Melanocytes are cells in low abundance in the epidermis that produce the pigment melanin. The pigment made in melanocytes is transferred to the cells of the hair or epidermis. The melanin granules are injected into (or ingested by) the keratinocyte cells. There, the melanin granules accumulate around the nucleus of each keratinocyte.
Melanin absorbs harmful ultraviolet (UV) light before the UV radiation can reach the nucleus. Melanin protects the DNA in the nucleus from UV radiation damage. When melanin is produced and distributed properly in the skin, dividing cells are protected from mutations that might otherwise be caused by harmful UV light.
Differences in skin color are due mostly to differences in the types and amount of pigment in our keratinocytes. Skin darkening (tanning) from sun exposure is caused by the movement of existing melanin into keratinocytes, and by increased production of melanin by the melanocyte.
During embryonic development these cells migrate from the neural crest into the skin.
Langerhans cells
These are star-shaped resident immune cells, macrophages. A macrophage is a cell that protects your body from injury or illness. Macrophages break up or destroy (phagocytise) the invading organisms. These macrophages process the invading organisms and present antigens to the T-lymphocytes. The T-lymphocytes are immune-system cells which ultimately identify a substance as foreign or dangerous to the body.
Merkel’s Cells
Only a few of these cells are present in skin; they are more numerous in the palms and soles (feet). These cells are probably sensory mechanical receptors that respond to stimulus, such as pressure or touch.
Schematic Drawing of Human Skin
Drawing (transverse section) of human skin illustrates the epidermis, basement membrane, dermis, capillaries and major cellular components.
A: Epidermis B: Dermis C: Cornified layer of keratinocytes (stratum corneum) D: Suprabasal keratinocytes E: Basal layer of keratinocytes (stratum basale) F: Basement membrane G: Collagen fibers in dermis H: Capillary (enclosed by a single microvascular endothelial cell) I: Melanocyte J: Dermal Fibroblast
The great majority of cells in the epidermis are keratinocytes, which are arranged in stratified layers. At the dermal-epidermal junction is a single layer of keratinocytes with a small number of interspersed melanocytes (approximately 1/30) called the stratum basale. This basal layer of keratinocytes is also called the stratum germinativum, because it is where new keratinocytes are generated by cell proliferation. Three types of keratinocytes in the stratum basale have been defined by kinetic analysis: stem cells, transient-amplifying cells and committed cells. Stem cells, which represent ~ 10% of the basal cell population, generate daughter cells from mitosis that are either stem cells themselves or transient-amplifying cells. Transient-amplifying cells, which represent ~40% of the basal cell population, replicate with much higher frequency than stem cells, but are capable of only a few population doublings. Transient-amplifying cells produce daughter cells that are committed to terminally differentiate. These committed cells detach from the basement membrane, differentiate, and ultimately cease to proliferate as they migrate toward the skin surface, where they are sloughed off as dead, cornified cells called squames.
Keratinocyte stem cells (like stem cells from other tissues) are relatively undifferentiated, both biochemically and histologically. Although keratinocyte stem cells have a high capacity for cell division, they divide with much lower frequency than transient-amplifying cells. Thus, when labeled with 3H-thymidine, stem cells retaiuclear label for long periods of time compared to transient-amplifying cells. Therefore, stem cells have been described as “label-retaining” cells. Because stem cells are undifferentiated, biochemical markers of stem cells are difficult to identify. However, keratin 19 expression has been suggested as a marker of keratinocyte stem cells, based on localization of keratin 19 expression to 3H-thymidine label-retaining cells. Keratinocyte stem cells may also express higher amounts of the a2 and a3 integrins, because an approximate 1.5-fold increase in the expression of these integrins has been observed in keratin 19-expressing cells relative to other epidermal basal cells. The retention and expansion of keratinocyte stem cells in culture is thought to be essential for using keratinocytes in ex vivo gene therapy.
The Epidermis
As the outermost skin layer, the epidermis forms the actual protective covering against environmental influences. Its thickness averages 0.1 mm. On the face it is only 0.02 mm, while on the soles of the feet between 1 and 5 mm.
Though paper thin, the epidermis is composed of many layers of cells. In the basal layer (the living epidermis), new cells are constantly being reproduced, pushing older cells to the surface. As skin cells move farther away from their source of nourishment, they flatten and shrink. They lose their nuclei, move out of the basal layer to the horny layer (the dead epidermis), and turn into a lifeless protein called keratin. After serving a brief protective function, the keratinocytes are imperceptibly sloughed off. This process of a living cell’s evolution, called keratinization, takes about 4 weeks.
The epidermis consists of up to 90 percent keratinocytes, the actual epidermal cells or dead skin cells, that are held together by what are called desmosomes. Keratinocytes function as a barrier, keeping harmful substances out and preventing water and other essential substances from escaping the body. The other 10 percent of epidermal cells are melanocytes, which manufacture and distribute melanin, the protein that adds pigment to skin and protects the body from ultraviolet rays. Skin color is determined by the amount of protein produced by these cells, not by the number of melanocytes, which is fairly constant in all races.
Hair and nails are specialized keratin structures and are considered part of the epidermis. While animals use fur and claws for protection and defense, these corresponding structures are largely cosmetic in humans. The skin, however, is uniquely human, since it can betray emotion by blushing (embarrassment), turning red (anger), blanching (fear), sweating (tension), and forming goosebumps (terror).
On the skin surface are the sweat gland pores (100-200/cm2) and the openings of the sebaceous glands (50-100/cm2). Their secretions ensure skin moisture and oiliness, and thus maintain the hydrolipid film. The epidermis itself has no blood vessels, so the nutrients are supplied through the fine blood vessels in the dermal papillae.
The epidermis is differentiated into five layers:
Schematic diagram of the epidermis: the basal cells change, through differentiation, into flat horny skin cells that are without nuclei.
1 Horny layer / 2 Clear layer
3 Granular layer /4 Prickle-cell layer
5 Basal layer / 6 Basal membrane
– Horny layer (stratum corneum)
– Clear layer (stratum lucidum)
– Granular layer (stratum granulosum)
– Prickle-cell layer (stratum spinosum)
– Basal layer (stratum basale)
Differentiation and skin regeneration
Through differentiation, the living, cylindrical basal cells lose their nuclei and become flattened cornified cells, changing their shape and composition in the process. The cells pass through the barrier zone, the border zone between the living epidermal layers and the horny layer, where the epidermal lipids are released.
Did you know that 90% of household dust is dead skin cells? Keratinocytes contain structural protein (keratin) and become progressively flattened as they advance upward from the basal layer to the corneal layer. The epidermis renews itself every 28 days through continual reproduction, differentiation / cornification and desquamation (mechanical sloughing-off of the uppermost horny cell layer).
The epidermis is a stratified squamous epithelial tissue. This means that it has several layers of epithelial cells and that its outermost layer is made up of squamous (flat) epithelial cells.
Mitotic Activity: The layer adjacent to the dermis is known as the basal layer. The basal layer is made up of columnar epithelial cells. Since all of the mitotic (cell-multiplying) activity of the epidermis occurs in the basal layer, the basal layer is often called the germinative layer. This mitotic activity involves about 4 percent of the cells in the basal layer at any given time. It occurs primarily between midnight and 0400 hours.
Migration of Cells to the Surface:
Scanning electron microscope image of scaling horny skin cells.
Over a period of weeks, new cells gradually migrate from the basal layer to the surface. During this migration to the surface, the cells change in shape from the original columnar to cuboidal and then finally to squamous. As the cells become squamous in form, they also become hardened, or cornified, through the development of a special type of protein. As they approach the surface, they die. Thus, the outermost layers of the epidermis are dead, horny scales.
Keratinocytes
Keratinocytes are stratified, squamous, epithelial cells which comprise skin and mucosa, including oral, esophageal, corneal, conjunctival, and genital epithelia. Keratinocytes provide a barrier between the host and the environment. They prevent the entry of toxic substances from the environment and the loss of important constituents from the host. Keratinocytes differentiate as they progress from the basal layer to the skin surface. The normal turnover time for keratinocytes is around 30 days but epidermal turnover may be accelerated in some skin diseases such as psoriasis.
Keratinocyte stem cells reside in the basal layer. These cells have a low rate of mitosis and give rise to a population of transient amplifying cells. (Figure 1) Transient amplifying cells go through a limited number of divisions, differentiate, and move up in the epidermis. The cells above the basal layer are known as the spinous layer. Under routine microscopy small bridges, resembling spines, can be seen between the keratinocytes which represent intercellular adhesion complexes known as desmosomes. As the cells further differentiate, they synthesize keratohyaline granules, a prominent feature of cells in the granular layer. Proteins synthesized in the granular layer are important in the final stages of epidermal differentiation and include profilagrin, loricrin, involucrin, and cornifin. These molecules are important in the formation of the stratum corneum, the outer most layer of the epidermis.
Keratin
Electron microscopical examination of cells from all tissues reveals that they contain a complex, heterogenous, intracytoplasmic system of filaments. The components of this system include actin, myosin, and tubulin, whose diameters average approximately 60A°, 150A°, and 250A°, respectively. In addition, other intracytoplasmic filaments were noted, and since the diameter of these latter structures was found to be between 70 and 100A°, they were called intermediate filaments.
Intermediate filaments form a major part of the cytoskeleton of most cells and fulfill a variety of roles related to cell shape, spatial organization, and perhaps informational transfer. The nucleus contains structures related to these intermediate filaments and many intracellular components including polyribosomes, mitochondria, nucleic acids, enzymes, and cyclic nucleotides are attached to the cytoskeleton.
Based on their biochemical, biophysical, and antigenic properties, a number of classes of intermediate filaments can be recognized in different cell types: desmin (skeletin) in muscle cells, glial fibrillary acidic filaments in glial cells, neurofilaments ieurons, vimentin in mesenchymal cells, and keratin in epithelial cells. In cultured epidermal cells, keratins account for up to 30% of the cellular protein, while in stratum corneum, keratin accounts for up to 85% of the cellular protein.
At least 19 keratin proteins can be identified ranging in molecular weight from approximately 40,000 to 68,000 micrograms. Moll and his coworkers published their human keratin catalogue in 1982. According to this catalogue, there are two keratin subfamilies. The molecular weight of the members of one (the basic subfamily) is relatively larger than that of the members of the other (the acidic subfamily). Each of the keratins is the product of a unique gene and, in essentially all situations, the keratins are expressed as pairs containing one member of each subfamily. The two members of each pair are in the same size rank order within their respective family, e.g., the largest acidic keratin is expressed with the largest basic.
The type of keratin differs in different tissues, i.e, there are different types of keratin for keratinized epidermis, hyperproliferative epidermis of palms and soles, corneal epithelium, stratified epithelium of the esophagus and cervix, and simple epithelium of the epidermal glands. As mentioned before, keratin is the main structural protein of the epidermis.
The Subcutis (Hypodermis)
The subcutis (sub = under; cutis = skin/Lat.) refers to the fat tissue below the skin. It consists of spongy connective tissue interspersed with energy-storing adipocytes (fat cells).
Fat cell clusters
Fat cells are grouped together in large cushion-like clusters held in place by collagen fibres called connective tissue septa or sheaths.
Nourishment, insulation and padding
The subcutis is heavily interlaced with blood vessels, ensuring a quick delivery of stored nutrients as needed. The functions carried out by the subcutaneous fatty tissue, beside the storage of nutrients in the form of liquid fats, include the insulation of the body from cold and shock absorption. On the palms of the hand, the soles of the feet and the buttocks, fat padding serves almost exclusively for shock absorption. (Note: Fats, also triglycerides or acylglycerins, are the most plentiful and simplest fatty acid-containing lipids. They are esters of the triol alcohol, glycerine with three saturated and/or unsaturated fatty acids. Fats make up the main component of the fat depots.)
Fat distribution in men and women
The fat content of the subcutis is not the same in all body regions. Also men and women differ in the distribution of subcutaneous fat. An example is cellulite – it is characterized by a special arrangement of the subcutaneous fat tissue septa and predisposes to fat deposition on the hips, thighs and buttocks – which occurs mostly in women. Men on the other hand tend to store fat on the torso.
Cosmetic lotions and toners.
Cosmetic lotion – is water-alcohol solution of active substances, produced for the skin, hands, body, legs and hair care.
Cosmetic toner- water solution of active substances, produced for the skin, hands, body, legs and hair care. Mostly toners used to care for dry skin because they do not desiccate the skin, due to absence of alcohol.
Classification:
Depending on skin type:
· for normal skin;
· for dry skin;
· for oily skin;
· for problem skin.
Depending on anatomical purposes:
· for face;
· for body;
· for hands;
· for feet;
· for hair;
By appointment:
· hygiene lotions;
· depigmenting lotions;
· medical lotions.
For cosmetic effect:
· nourishing lotions;
· bleaching lotions;
· ant aging lotions;
· after shave lotions, etc
Characteristics and functionality of the main components of cosmetic lotions.
Solvents – are the dominant ingredients.
Purified water is primarily used as a solvent in cosmetics and personal care products in which it dissolves many of the ingredients that impart skin benefits, such as conditioning agents and cleansing agents. Water also forms emulsions in which the oil and water components of the product are combined to form creams and lotions. These are sometimes referred to as oil-in-water emulsions or as water-in-oil depending on the ratios of the oil phase and water phase. Water has a pH close to the skin pH 5.0 – 7.0 is an excellent solvent for a variety of ingredients. Disadvantage – easy to microbiological contamination. Water is a dominant component in lotions and toners (10 – 90%).
Thermal water is defined as hot water containing salts, iodine and gases emerging from natural thermal springs in various regions of the world. The groundwater coming from hot springs in heated by geothermal processes and naturally flows to the land surface at the temperature of 70°F (approximately 21°C) or above.
Thermal water contain:
Calcium: It is the most important mineral element in the organism. It maintains the effect barrier of the skin and reaches port humectación. Its application of local form helps to reduce the process of aging of the skin and the negative effects of the exhibition UV.
Copper: It works on the cellular regeneration and it is reestruturante, since it favors so much the synthesis of collagen, of melanin and of keratin. Also, he collaborates like activator in the processes of tanned.
Magnesium: It contributes an effect energizante and collaborates in the inhibition of the inflammatory processes.
Zinc: It restructures the skin since it takes part in the keratin synthesis. Also it possesses moisturizing and anti-inflammatory action. Also, it manages to resist and improve the acne pictures because it takes part in the tallow regulation.
Sodium: It helps to control the water balance of the skin.
Fluorine: He stands out for its antiseptic action on the skin.
Selenium: He prepares the cutaneous aging for its antirust effect.
Cosmetic lines in thermal water: Spa Vosges, Sans Soucis, GamARde, Thermal line, deKAROline, Avene, Vichy, Uriage
Ethyl alcohol contains in lotions in amount about 17-90%. Ethanol is widely used in cosmetics as a solvent and as an antibacterial agent. As a preservative, it’s effective at concentrations of 15% to 20%. It’s a antitoxin in concentrations of 60% to 70%, with a bactericidal effect within 45 seconds. It’s also used in acne treatments and in rinses for oily hair. Ethanol absorbs water and thus can be very drying in fast-drying skin lotions (at concentrations of 15%); the lotions need to include glycerols and vegetable oils to minimize the drying effect.
Solubilizing Agent – are substances which are added to cosmetic products to lower the surface tension as well as to aid the even distribution of the cosmetic product, when used. Its improve the solubility of substances with different physical-chemical properties due to their hydrophilic-hydrophobic properties. Included in cosmetics in an amount up to 2%.
As solubilizing agent commonly use PEG-40 Hydrogenated Castor Oil, Polysorbat-80 (tween 80, polyoxy-ethylene (20) sorbitan monooleate), Polysorbate-20 (tween 20, Е432, EUMULGIN ® SML 20), ethyl alcohol, glycerin, propylene glycol etc.
Emollients are substances which are added to cosmetic products to soften and smoothen the skin, any substance that softens the skin by slowing evaporation of water. Sesame, almond, and olive oils were used in ancient Egypt; beeswax, spermaceti, almond oil, borax, and rosewater in Greece; and lanolin (sheep fat) in medieval Europe. Modern emollients include wax (beeswax, candelilla, carnauba), natural fats and oils, ceresin, mineral oil, esters (isopropyl myristate, isopropyl palmitat, etc.), fatty alcohols (stearic alcohol, etc.), lanolin and its derivatives, silicones (dimethicone, cyclomethicone, etc.), glycerin etc.
Some commonly used emollients cause clogging of sebaceous glands and blackheads (comedogenic effect).
Comedogenic action have:
· free fatty acids and their derivatives,
· lanolin,
· coconut oil,
· almond oil undiluted,
· isopropyl,
· isopropyl alcohol etc.
Humectants (or moisturizers) are important cosmetic ingredients allowing to prevent loss of moisture thereby retaining the skin’s natural moisture.
Some compounds also have the ability to actively attract moisture. Humectants are key ingredients in most skin care products but are also often used in hair care products to volumize the hair by attracting moisture which expands the hair shaft. There is a large variety of very different compounds providing moisturzing effects including proteins, acids, polysaccharides, and various small molecules (e.g. glycerine, sorbitol, urea, collagen protein hydrolyzed, hyaluronic acid, propylene glycol, aloe vera etc.).
Absorbents are substances which are added to cosmetic products to take up water- and/or oil-soluble dissolved or finely dispersed substances:
kaolin
talc
dextrin
oryza sativa starch
magnesium oxide
microcrystalline cellulose
bentonite
bismuth subnitrate
calcium silicate
cellulose
Biological additives are substances derived from biological origin which are added to cosmetic products to achieve specific formulation features:
chitosan
collagen
elastin
lactis proteinum
maris sal
yogurt
yeast polysaccharides
placental enzymes
egg yolk
honey
Botanicals are substances which are derived from plants, mostly by physical means, added to cosmetic products to achieve specific formulation features.
Different extracts, such as
Horse chestnut
Arnica Montana
Tea chinensis
Centaurea cyanus
Bergamot
Coffee
Ginkgo biloba
Hamamelis virginiana
Oak
Ivy
Preservatives are substances which are added to cosmetic products for the primary purpose of inhibiting the development of microorganisms therein.
benzalkonium chloride
benzoic acid
butylparaben
diazolidinyl urea
dmdm hydantoin
formaldehyde
phenoxyethanol
potassium sorbate
salicylic acid
triclosan
benzyl alcohol
Active components it is a large group of cosmetic ingredients, which have different positive influence on the skin such as: anti-inflammatory properties (aloe vera, allantoin d-panthenol), exfoliating agents (salicylic acid and glycolic acid) and others.
Lotion technology.
The technological process of preparing lotions consists of the following stages:
1. Preparation of raw materials.
2. Preparation of lotion:
– Dissolving alcohol-soluble substances;
– Dissolving water-soluble substances;
– Preparation of alcohol-water solution;
– Adding active components;
– Settling;
– Filtering.
3. Packing, packaging, labeling the finished product.
Skin care sales continue to grow globally, driven by innovative new product forms, multifunctional products, consumer interest in reducing the signs of aging, a rise in disposable income, and the availability of foreign product lines in formerly less-developed countries. Most of the increase in sales is generated by anti-aging/nourishing products. Dermatologists’ skin care lines with scientific-sounding names and minimalist packaging are increasingly popular with the consumer who feels these lines may provide efficacy at an affordable price without a prescription. Euromonitor (1) reported toner sales worldwide in 2004 at $4.7 billion, growing at a lower rate than other skin care categories. Growth in toner sales in 2004 came from Asia-Pacific, Western Europe, Eastern Europe, and Latin America where multistep regimens are well received. In the U.S., where convenience is a key factor in product usage, sales peaked at $384.7 million in 1999 and then began a gradual decline which is forecasted to continue. The perception among some consumers that toners are unnecessary or harmful because they “strip” the skin, the lack of innovation in the product form, and inconvenience are among the reasons toner sales have declined. Toners are often perceived as harmful because consumers tend to associate them with drying of the skin and high alcohol levels. At one time toners were touted as pH balancers and necessary to remove the highly alkaline, drying, irritating residue of cleansers and soaps of the past. Most cleansers marketed today are mild and well formulated so as not to disrupt the skin’s pH level, thus minimizing the perceived need for toners. In addition, toners have not advanced from the traditional solution form. Consumers prefer the convenience of facial cleansing wipes and multifunctional products, such as two-in-one cleanser/toner and three-in-one cleanser/toner/mask products, rather than the additional step of a toner. Despite this, there are opportunities for the dermatologist, aesthetician, and consumer to use a toner that is cosmetically acceptable, provides a sensorial experience, is suitable as a delivery vehicle, and is formulated appropriately for skin type.
PRODUCT NOMENCLATURE
Toners, astringents, skin fresheners, skin lotions, softeners, tonics, balancers, cleansing waters and other terms are used for products in this category. The choice of nomenclature can vary by manufacturer and even within product lines. Also, the product name does not necessarily indicate strength or inclusion of a particular ingredient. For this chapter the term toners will be used to cover all these nomenclatures unless specified. Toners may be categorized as cosmetics or over-the-counter (OTC) drug products, depending upon the claims and ingredients. There is an astringent category under the Food and Drug Administration’s (FDA’s) Skin Protectant Drug Products for Over-the-Counter Human Use (2) defining astringents as “.(products) applied to the skin or mucous membranes for a local and limited protein coagulant effect.” This definition covers the use of aluminum acetate, aluminum sulfate, and witch hazel. Active ingredients and labeling claims in astringent drug products are dictated by the FDA OTC Monograph (2). Except for witch hazel (hamamelis water) USP, these actives are reserved for OTC uses and are not typically used in cosmetic toners and, therefore, will not be considered for purposes of this chapter. To add to this confusion, there are products branded as toners and astringents containing cosmetic ingredients as well as toners and astringents containing salicylic acid that are sold in accordance with the FDA’s OTC Acne Drug Monograph (3).
FUNCTION AND ORDER OF APPLICATION WITHIN A SKIN CARE REGIMEN
Toners are leave-on products. They are the second cleansing step within a skin care regimen designed to freshen and tone, and they also prepare the skin for the application of moisturizer. After cleansing, toners are typically applied by saturating a cotton ball or pad and wiping this across the face. Men may use them as a splash-on after shaving. Toners remove any makeup residue, and oily skin patients find them beneficial to remove excess sebaceous secretions. Toners can provide a mild exfoliating action and a stimulating or cooling sensation. Toners may also serve as a delivery vehicle for active or cosmeticeutically important ingredients such as anti-acne, anti-aging, and whitening/ lightening. Although toners are typically designed for facial use, they may also be used for the upper chest and back in acne treatment.
FORMULATION CONSIDERATIONS
Product Forms and Ingredients
Toners are typically clear to translucent aqueous or hydroalcoholic solutions. The choice of ingredients, function of these ingredients, and claims determine the product’s appearance and type of solution. A generic base formulation is shown in Table 1. Water is typically the major component and main vehicle or delivery system for active or other cosmetically important ingredients. Ethanol may be added as part of the vehicle as desired for skin type and/or ingredient solubility. Ethanol is generally not used in toners formulated for dry or sensitive skin or in the Asia-Pacific market, but it is found at varying levels iormal, combination, oily, and acne-prone skin types. Ethanol also serves as a preservative when used at levels of 20% or higher. Various types of denatured ethanol are used in toners, depending on country regulations on the denaturant. Isopropanol was used years ago, but it is now out of favor because of its strong odor. Humectants are added to attract moisture to the skin, mitigate the drying effects of alcohol, lower the freeze point to ensure stability in cold temperatures, solubilize other
Toners and Astringents
Table 1 Skin Toner—Base Formula with Typical Concentration Ranges
Ingredients %
Water Qs to 100.00%
Ethanol 0.00–65.00
Humectants 1.00–5.00
Key ingredients 0.10–10.00
Emollients 0.10–3.00
Cosolubilizers 0.10–0.50
Thickeners/film formers 0.05–0.20
Preservatives As needed
Color, fragrance Qs
ingredients, and adjust the aesthetics. Glycerin and sorbitol are the most cost effective humectants, but they can lend a tacky afterfeel. Sodium polycarboxylic acid (PCA) is less tacky, but more importantly, it is similar to the PCA which is found in the skin’s owatural moisturizing factor (NMF). When additional solubility and an elegant, smooth, non-tacky feel is desirable, propylene glycol, butylene glycol, polyethylene glycols, and the ethoxylated glycerins, such as methyl gluceth-10 or methyl gluceth-20, are used. Sodium hyaluronate and other water-soluble moisturizing agents may be added. Emollients, such as dimethicone copolyols and small amounts of natural oils, are beneficial for skin lubricity and soothing. They require the use of cosolubilizers to assure ingredient solubility to maintain product clarity and stability. Cosolubilizers include ethoxylates and propoxylates, such as PEG-40 hydrogenated castor oil, PPG-5-ceteth-20, or polysorbate 20. They are added at concentrations of 0.10–0.50%, depending on the oil-soluble ingredient and level used. The ethoxylated and proproxylated humectants are also useful but less efficient cosolubilizers. Botanical extracts are added for a variety of reasons (4–6). The concentration is dependent on many factors, including the type of extraction and the percent solids of the extract. For example, aloe extract and witch hazel distillate are often used as vehicles. Frequently, several botanicals will be incorporated into a toner. Some extracts are more suitable for specific skin types; some offer multiple benefits. They are frequently touted as the key ingredient that offers benefits such as astringency, anti-inflammation, antioxidant, exfoliating, soothing, and cooling. It is the extracts’ polyphenolic content that offers one or more of these benefits. Especially popular and beneficial are the polyphenolic bioflavinoids found in green tea, rosemary, blueberry, raspberry, strawberry, red wine, grapeseed, and pine bark extracts. They provide antioxidant and anti-inflammatory benefits. The anti-inflammatory benefits equate to soothing the skin by reducing skin stinging, itching, and redness. Extracts of honey, mallow, soy, aloe, lavender, green tea, algae, licorice, and chamomile may be added for their soothing and conditioning effects on the skin. The high tannin levels in botanical extracts such as witch hazel, sage, horsechestnut, and quercus lusitanica oak provide astringency. In addition to its astringency, the distillate of witch hazel, which contains 14% ethanol, also provides a cooling effect on the skin. It may be claimed as an OTC drug product astringent under the Skin Protectant Monograph (2), but both the distillate and extracts forms are more frequently used as a cosmetic ingredient in skin toners. Isoflavones, such as soy extract, known for their phytoestrogen content, are beneficial to more mature and dry skins. Other beneficial ingredients used in toners are allantoin and panthenol for conditioning and soothing of the skin, and free radical scavenging antioxidants, such as alpha lipoic acid, superoxide dismutase, and vitamins A, C, and E. Vitamin E and its derivative, tocopheryl acetate, can also be used to protect the product and its constituents from oxidization. Alpha-hydroxy acids (AHAs) such as glycolic, lactic, malic, citric, and mixed fruit acids are used for exfoliation and/or pH adjustment. While they are not marketed as toners, the toner product form has been used by aestheticians and dermatologists to deliver high levels of hydroxy acids in chemical peels for years, and more recently chemical peels with lower levels of AHAs have been introduced through the retail market. AHAs at efficacious exfoliating levels of pH !5 may cause skin stinging and redness, so the addition of antiinflammatory and soothing botanical extracts is recommended. Although neutral pH ranges offer less irritation potential, they do not offer the same exfoliation activity. Polyhydroxy acids (PHAs), larger molecular weight variants of AHAs, are designed to be less irritating (7). Both AHAs and PHAs may be used in both aqueous and hydroalcoholic solutions. When used as a pH adjuster, AHAs are added at levels of 0.01–0.20%. The beta hydroxy acid (BHA), salicylic acid, is used for its keratolytic/exfoliating activity and is monographed as an OTC anti-acne drug (3). Whitening agents have a long history of use in Asia. They are highly regulated in Asia as quasi-drugs. They have gained popularity in the rest of the world for the cosmetic claim of even skin tone, where the term whitening is considered a drug claim. Licorice, mulberry, and bearberry are popular skin lightening botanical extracts. The oil-soluble form of licorice at 0.05% is regulated as a functional drug in Korea (8). The water-soluble vitamin C derivatives, magnesium ascorbyl phosphate (MAP) used at 3%, and ascorbyl glucoside at 2%, are recognized as quasi-drugs in most of Asia (9). MAP is highly unstable and turns brown readily with time, high temperatures, and exposure to light. Ascorbyl glucoside is preferred for its acceptable stability profile. Thickening ingredients are added when a slightly viscous and/or film forming property is desired. They also provide a more lubricious application and afterfeel than a solution. Xanthan gum, polyacrylic acids such as carbomer, and cellulose gum derivatives, such as methylcellulose, hydroxypropylcellulose, and hydroxyethylcellulose, are used. Fragrance oils or naturally derived extracts and oils may be added to impart a pleasant scent to the formula or cover off-odors that develop when the product is exposed to excessive heat, light, or other parameters associated with shelf life. They also can be used to support a toner’s marketing position and enhance the message that the toner is soothing or refreshing or, in the case of anti-acne toners, medicinal. Rose and lavender extracts can be used for soothing and dry skin formulas. Rosemary, peppermint, and citrus extracts may be added to toners designed for oily and combination skins or when a refreshing, stimulating signal or scent is desired. Menthol, peppermint, and eucalyptus odors are associated with a medicinal benefit. Like fragrance, color is included to deliver a sensorial signal, such as soothing, refreshing or therapeutic, or to enhance the product’s appearance, or to cover product color stability issues. Water-soluble Food, Drug, and Cosmetic (FD&C) and Drug and Cosmetic (D&C) colorants are used.
New and Patented Ingredients/Applications
Toners have historically contained plant-derived key ingredients. With recent controversies in the cosmetic industry concerning the use of animal-derived ingredients, the use of collagen and other animal-derived ingredients has diminished, and they are very rarely found in toners outside of Japan. A recent U.S. patent discloses the use of extensions, plant-derived hydroxyproline-rich glycoproteins that can be incorporated into toners as substitutes for animal collagen (10). The use of Morinda Citrifolia or Noni from the Indian Mulberry plant in a toner is disclosed in a recent patent. Noni provides antioxidant benefits and is high in linoleic acid to nourish the skin (11). Sanguisorba, a plant native to Korea, China, and Japan, produces a root extract widely used in Asian cosmetics for its astringent effect. It is said to offer antimicrobial and anti-inflammatory effects as well, and it functions much like superoxide dismutase as an antioxidant (12). A recent patent discloses the preparation zinc glycyrrhizinate for use as an astringent in medical and cosmetic preparations (13). A mixture of butylene glycol and mushroom extract is used as an astringent additive for its skin tightening benefits (14). Pycogenol or pine bark extract and blueberry extract exhibit potent antioxidant and anti-inflammatory actions. They are useful as soothing and antioxidant agents in toners (15). Another recent patent (16) discloses the use of solvent extracts of plants including Spondias mombin, Maprounea guianesis, Waltheria indica, Gouania blanchetiana, Cordia schmoburgkii, Randia armata, and Hibiscus furcellatus to stimulate autosynthesis of reduced glutathione. A skin toner formulation patent (17) covers the use of butylene oxide-based ethers and propylene oxide-based ethers. It is purported to remove sebum from the skin without significant removal of moisture-retaining intercellular lipids.
Formulation Challenges
Skin Types
Toners have two key formulating challenges—formulating for specific skin types and vehicle/ingredient stability and compatibility. Varying skin types, including dry, normal, oily, combination, sensitive, and acne-prone, require different and skin-type specific ingredients and vehicles. Free radical scavenging antioxidants are used regardless of skin type. Most toners are used within a skin care regimen. The patient’s concern about toners being drying or harmful may be mitigated by using a regimen and toner appropriate for skin type. Alcohol-free formulas with humectants, emollients, and soothing agents are most suitable for the dry and sensitive skin patient (Table 2). This, in conjunction with the use of a moisturizer, allays the concern of a toner being drying. The addition of humectants and emollient agents will help maintain moisture balance. Soothing ingredients are beneficial to alleviate the redness and irritation often experienced with these skin types. Sensitive
Table 3
Skin Toner for Oily Skin
Ingredients % Function
Water QS to 100% Vehicle
Ethanol 20.0 Vehicle, astringent, preservative,oil removal
Witch hazel distillate 20.0 Astringent, cooling and soothing effect
Glycerin 5.0 Humectant
Fragrance, color As needed
Alcohol-free toners may be used as a last step in cleansing, a preparation step to moisturizing, or as a whitening treatment product in the Far East. Toners are frequently sold under the “softener” nomenclature in Asia. Asian consumers have a negative perception of alcohol in terms of both skin reactions and odor of ethanol. They exhibit a higher degree of sensitivity to the skin effects of alcohol (23). It is advisable to avoid the use of alcohol and sensorial-stimulating agents to minimize the chance of irritation. Botanical extracts and the quasi-drug ascorbyl glucoside are used for whitening effects in toners. Another popular toner form in Asia is the lightweight, low-viscosity milky lotion. These are frequently used to prepare the skin as the first step of the moisturizing regimen. The milky lotions are alcohol-free. Collagen, hyaluronic acid, and whitening agents are popular in these products. Ingredient and Vehicle Stability and Compatibility Considerations Requirements of pH, ingredient solubility and compability, and product stability influence the choice of ethanol-to-water ratios, humectants, and cosolubilizers. Hydroxy acids require low pH to be effective as exfoliants. Fortunately, they also act as pH adjusters when a low pH is desired. This low pH limits the choice of film formers and thickeners. There are also pH and concentration limitations when using AHAs in retail products sold in the U.S. The Cosmetic, Toiletry, and Fragrance Association’s Cosmetic Ingredient Review (CIR) Expert Panel recommends that cosmetic products containing glycolic and lactic acids and their salts and esters be formulated at pH R3.5 and at concentrations %10% (24). Oil-soluble ingredients such as emollients, fragrance oils, and vitamins A and E require cosolubilizers to assure ingredient solubility to maintain product clarity and stability. The use of these cosolubilizers may cause product foaming during production filling and consumer use. This foaming can be minimized by adding an ingredient such as simethicone to reduce surface tension. Tea tree oil, found in many anti-acne and oily skin toners for its antibacterial activity, requires solubilizing agents for a clear solution, has a distinctive odor and its terpene constituents are highly susceptible to oxidation. The oxidation potential impacts the safety of the product (18–21); therefore, a recent European Cosmetic Toiletry and Perfumery Association (COLIPA) report recommended that manufacturers add antioxidants and/or packaging that minimizes the product’s exposure to light (25). High levels of ethanol in a toner can solubilize oil-soluble ingredients without the need for additional cosolubilizers. Easier to use water-soluble botanical extracts are more commonly used to provide antioxidant, anti-irritant, and soothing benefits, thus negating the need for cosolubilizers and mitigating any drying effects of alcohol. Alcohol-free toners or toners with less than 20% alcohol require preservatives to maintain microbiological quality.
PRODUCT CLAIMS
Toners on the market tout a plethora of skin benefit claims. It is these benefits that offer a prime opportunity for toner acceptance. The benefit most frequently associated with toners is a reduction of apparent pore size. Although no cosmetic product can alter the actual size of the pores, this claim is achieved because the pores appear less prominent due to an astringent effect that results in swelling of the skin surrounding the pore or removal of oil and dirt from the pore. “Purifies skin by removing dirt and oils” and “removing (or) controlling oil” are claims used in oily skin toners. The toner claims, “restores the acid/alkali balance of the skin” and “pH balanced,” still resonate well with consumers although they go back to the days of highly alkaline cleansers. Sensorial claims include “skin looks healthy,” “even skin tone,” “softens,” “soothes,” “refreshes,” “energizes,” “cools skin,” “warms skin,” and “tightens.” Lightening and whitening claims such as “whitens (or lightens) the skin” and “reduces dark spots” are popular in Far East whitening toners. These claims may be quasi-drug or cosmetic depending on the country, ingredient, and claims. The “evens skin tone” claim is gaining popularity in the rest of the world.
CLAIMS TESTING METHODS
Toner claims are substantiated by subjective and objective measurements. Many claims are substantiated by using both measurements. These tools are useful in the screening of ingredients and final product efficacy. Subjective measurements include consumer perception testing and panelists self-assessment on clinical trials. These tests include yes/no, like/dislike, agree/disagree, and point scales to rate consumer perception. Point scales may be a three-, five-, seven-, or 10-point scale. For example, using a five-point scale of “much worse,” “slightly worse,” “no change,” “slightly improved,” or “much improved” would offer the panelists the option to rate the skin’s appearance and condition. Another method is the use of a line marked in units from one to 10 designating least to most, where the panelists mark product attribute agreement. Objective measurements include expert grading, photography, and instrument measurements. The expert grader is trained in visually assessing the skin for changes in color for evenness of skin tone, reduction of pore size for tightening and astringent claims, and reduction of the appearance of fine lines and wrinkles for anti-aging claims. Photography and more recently VISIA CRe is used to capture these same measures on a permanent record. Instrumental measures include the Sebumetere and Sebutape (CuDerm Corporation, Dallas, TX) (Fig. 1) to measure oil control. The Gas Bearing Electrodynamometere assesses skin softness, and the Minolta chromameter measures skin tone and color. Chromameter measurements are useful in measuring skin tone and color in products claiming evenness of skin tone or skin whitening as well as the reduction of redness when measuring anti-irritant and anti-inflammatory benefits.
USES IN DERMATOLOGY
Until recently, the use of astringents and toners in dermatology was primarily limited to their anti-acne and astringent properties, although some also functioned as mild antiseptic agents suitable for mild or limited bacterial infections of the skin surface (24). Today soothing toners are increasingly being used by dermatologists and aestheticians for their anti-inflammatory and anti-irritant benefits as part of a post-cosmetic surgery regimen such as laser, chemical peel, or light-modulated procedures. The perceptual attributes of clean and refreshing for oily and acne-prone skins and soothing and calming for dry and sensitive skins in a cosmetically acceptable toner formulation assure patient compliance when compared with traditional drug vehicles that lack the aesthetic characteristics preferred by patients (26). Figure 1 Macroscopic view of Sebutapes taken from oily skin surface before (left) and after (right) toner treatment. The fewer and smaller black spots on the right indicate a reduction in sebum after treating the skin with an oily skin toner. The number of pores and amount of sebum secreted can also be determined via image analysis.
ADVERSE REACTIONS
Adverse reactions in toners include transient contact irritation, contact allergy, and sensitization. Contact allergy is most often seen with more pharmacologically complex products, such as those containing multiple botanical extracts and penetration enhancers (27). Propylene glycol is often used as a humectant and sometimes as a solvent in toners. It is approved for use in concentrations up to 50%by the CIR (28), but caution is advised in using it above 10% as it can act as a penetration enhancer and cause irritation which, in patch testing, is often confused with comedones. Although tea tree oil is not recognized by the FDA as an anti-acne, antiseptic or antibacterial active ingredient, it is found in many antiacne and oily skin toners. It also has a distinctive odor, and recently there have been several reports on the allergic, sensitization, and irritation potential of tea tree oil (18–21,29). COLIPA recommended that it not be used in cosmetic products at concentrations greater than 1% (25). Increased sun sensitivity occurs from topical application of AHA-containing products. Recently, the FDA issued industry guidance for labeling these products with a sunburn alert to minimize this risk (30). Toners have very low rates of reported adverse reactions compared to other skin care products. FDA statistics for the years 1991–1994 show 7.07 reported adverse reactions to toners and fresheners per million units sold, (31) and no consumer complaints were reported from 1995–2003 (32).
Lotion Making
Lotion making is fun and easy once you get the hang of how it works. This is a brief overview of the things to keep in mind when creating lotions and creams.
Introduction
Lotions and creams are emulsions – they are either water in oil (w/o) or oil in water (o/w). A w/o emulsion means you have small droplets of water dispersed in a medium of oil. A o/w emulsion means you have small droplets of oil dispersed in water. So the first 2 key ingredients of a lotion/cream are the oil and the water.
Emulsifiers
But as you know, oil and water do not like each other and therefore will separate if you don’t have the 3rd key ingredient – an emulsifier. An emulsifier is an agent that helps bind the water and the oil together in a formula so it will not separate. Emulsifiers have different strengths or HLB values (hydrophilic lipophyllic balance) and therefore you need to choose your emulsifying agent carefully. Emulsifiers with low HLBs (3-7) are good for w/o creams or recipes that tend to separate slowly. A good example of a low HLB emulsifying agent would be a beeswax and borax combination. Higher HLB (10 – 18) emulsifiers are required when making o/w lotions. Emulsifying wax, liquid or solid soap and polysorbate 20 are examples of high HLB emulsifiers and are necessary when trying to make lotions or recipes that separate readily.
Creams Vs. Lotions
Creams are usually about 2/3 oil phase (oils, butters, waxes) and 1/3 water phase (all water soluble ingredients) while lotions are about 2/3 water phase and 1/3 oil phase. 5% beeswax is generally sufficient to give your emulsion body. These ratios can be adjusted according to your needs. The amount of emulsifier depends on what you are using but generally you will need about 5-10% if using an emulsifying wax or 15-20% if you are using polysorbate 20. Remember to add the preservatives to the correct phases before you combine phases. Water based preservatives should be stirred into the water phase and oil based preservatives should be stirred into the oil phase. The smaller phase should be added very slowly to the larger phase with constant mixing (mechanical mixing is recommended). The lotion/cream will change consistency somewhat as it cools so you may find that you need to adjust your recipe if it becomes thicker than you expected upon cooling.
Preserving Your Lotion
The last necessary components of your lotion or cream are the preservatives. Because your formulation contains both oil and water, you will need to protect both. Oils go rancid when they come in contact with oxygen and must be protected using an anti-oxidant. T50 vitamin E oil is a low alpha tocopherol suitable for this purpose. Rosemary oil extract is another. These can be used at .2- .5% and must be added to the oil phase. Water is susceptible to bacterial, fungal and yeast growth and must have an anti-microbial agent added to it. Paraben complexes and grapefruit seed extract are examples of anti-microbials. These should be added to the water phase at their recommended rates.
Oil Selection
Chose your oils carefully according to the feel you want for your product. Heavy oils such as avocado and hemp are nice for winter creams but may be too oily for light formulas. Lighter oils are preferred for summer use such as grapeseed, apricot kernel, peach kernel, sweet almond etc. Fractionated coconut oil is both light and penetrating making it a good addition to any formulation. It will help carry other oils deep into the skin and prevent them from sitting on the skin. Using fractionated coconut oil will reduce the greasy feeling of most oils and butters.
Thickening Agents
Sometimes you will need to add a thickening agent to your lotions or creams to help attain the texture and spreadability you are looking for. Vegetable gums and starches are generally used to increase viscosity and improve the feel of the product. Look for easy to dissolve gums that do not require pH buffering. Xanthan gum can be used for this purpose.
Hydrolyzed silk can be used to provide a silky slip to your formulation. Modified starches (coming soon) can be used at 1-5% to reduce the heavy greasy feeling of the oils and waxes.
Heating
Generally, the first step in the process involves heating the oil phase – the waxes and solid fats. The water phase should be warmed too and both phases should be equal in temperature when the phases are combined.
Coloring and Fragrancing
Creams and lotions are easily colored with the use of liquid FD & C dyes as they readily mix with water. Insoluble colorants are not a good choice for lotions as they tend to settle to the bottom. Scent your lotions and creams once they have cooled slightly by stirring in your fragrance or essential oils.
Sterilization
Finally, make sure that all of your equipment is clean and sterilized. Use glass and stainless steel for mixing. Bottles can be sterilized ahead of time using a solution of water and alcohol or water and bleach. Use only distilled water not tap water. Avoid touching the batch with your hands during transfer.
