Ferric Ferrocyanide Contact Dermatitis

D&C Green #5; good light stability

Quinoline o o

D&C Yellow #10, D&C Yellow #11; oil soluble

D&C Red #30; good chemical, light, bleed resistance; exception: acetone soluble

Stability of Organic Pigments

True pigments > Toners > True Lakes

Light: Anthraquinone > Quinone > Indigoid > Azo > Triarylmethane > Xanthene Heat: True pigments stable to heat. Toners: D&C Red #7 Ca lake changes reversibly Lakes: D&C Red #27 Al lake changes irreversibly pH: 4-9

Metal ions: Unstable

Solubility: True lakes tend to bleed in water, Fluorescein lakes bleed in solvent

Natural DDyes [10]

Generally used in foods, there is no restriction on their use in cosmetics. For the most part, the resistance of natural dyes to heat, light, and pH instability is much inferior to their synthetic counterparts. A further disadvantage is that they often tend to exhibit strong odors.





















Coccus cactii






Red berries



Lucerne grass



All of the above are of vegetable origin, with the exception of cochineal which is extracted from the crushed insects Coccus cactii.

Color Chemistry and Manufacture

The property of a colorant that makes it absorb more in one part of the visible spectrum than another is its chemical constitution. Molecules, like atoms, exist in different electronic states. Because molecules contain two or more nuclei, they also possess energies of rotation and vibration. This theory applies to both organic and inorganic colorants. With the inorganic colorants, colored compounds are obtained with the ions of the transition elements that have atomic numbers 22 to 29.

Inorganic Pigments

Titanium Dioxide

A brilliant white pigment. Two crystal types occur: anatase and rutile. Two manufacturing processes are used:

1. Sulfate—either crystal may be produced.

2. Chloride—only rutile crystals are formed properties. Crystals of both rutile and anatase are tetragonal, rutile having greater hiding power because of the closer packing of the atoms in the crystal. Refractive indices are 2.55 for anatase and 2.71 for rutile. Opacity is the result of the light-scattering ability of titanium dioxide. Light, heat and chemical stability are excellent. Additionally, in the United States, titanium dioxide is a Category I sunscreen.

Zinc Oxide

Zinc ore is roasted and purified at 1000°C. Two methods of manufacture are used: 1) French (indirect) and 2) American (direct).

Properties. Zinc oxide forms transparent hexagonal crystals; whiteness is attributable to the light scattering of the extremely fine particles. Refractive index is 2.0. Hiding power is less than titanium dioxide. Primary use is for antibacterial and fungicidal properties. Heat and light stability are good. It is soluble in acid and alkali. Zinc oxide in the United States is a Category I skin protectant and a Category III sunscreen.

Iron Oxides

These are used in all types of cosmetic products. By blending black, red, and yellow in certain properties, brown, tans, umbers and sienna may be produced. Yellow iron oxide is hydrated iron II (ferrous) oxide, Fe2O3XH2O. It is produced by the controlled oxidation g of ferrous sulfate. Red iron oxide is chemically Fe2O3 and is obtained by the controlled g heating (at about 1000°C) of yellow iron oxide. Black iron oxide is Fe2O4 and is a mixture of ferrous and ferric oxide and is prepared by controlled oxidation of ferrous sulfate under alkaline conditions.

Ultramarines ts

Theoretically they are polysulfide sodium/aluminum sulfosilicates. They range in color

from blue to violet, pink, and even green. A mixture is calcined at 800°C to 900°C, for s

4 to 5 days. Shades are determined by reaction time, formula variations, and particle size, 2

whereas ultramarine violets and pinks are obtained by treating ultramarine blue with HCl at 275°C, removing some sodium and sulfur from the molecule.

Manganese Violet

Chemically this is MnNH4P2O. Manufactured by heating manganese dioxide with ammonium dihydrogen phosphate and water. Phosphorus acid is added and the mixture is heated until the violet color develops.

Iron Blue

Chemically ferric ammonium ferrocyanide. Fe[Fe(Cn)6]3. Sodium ferrocyanide and ferrous sulfate are reacted in the presence of ammonium sulfate. Pigments prepared with sodium or potassium salts are called ferric ferrocyanide.

Chromium Oxide (Cr2O3)

A dull yellow green pigment may be prepared by blending an alkali dichromate with sulfur or a carbonaceous material. Reduction to chrome (III) oxide is achieved in a kiln at 1000°C.

Chromium Hydroxide (Cr2O(OH)4)

A bright bluish green pigment prepared by the calcination of a bichromate with boric acid at 500°C. During cooling, the mass is hydrolyzed with water, yielding a hydrate.

Hydrated Alumina

Chemically Al2O3 X H2O gives little opacity and is almost transparent. Barium Sulfate

It is relatively translucent and may by used as a pigment extender.

Organic Pigments

These are chiefly conjugated cyclic compounds based on a benzene ring structure, although some heterocyclic ones exist. There are three main types: lakes, toners, and true pigments. Organic pigments are seldom used without a diluent or substrate in order to maintain color consistency from batch to batch. A true pigment is an insoluble compound that contains no metal ions, examples of which are D&C Red #30 and D&C Red #36. They are the most stable. A lake is essentially an insoluble colorant, produced by precipitating a permitted soluble dye to a permitted substrate. In cosmetics, most lakes are based on aluminum, although zinconium lakes are also found. Stability-wise, true aluminum lakes can be affected by extremes of pH, resulting in reforming of the soluble dye or ''bleeding.'' They are fairly transparent and not particularly light-fast. Toners are colorants made with other approved metals besides aluminum, such as barium and calcium. Generally, they are more resistant to heat, light and pH, although extremes of pH can result in shade changes. Generally, many organic colorants are unsuitable for certain cosmetics because of their chemical nature. D&C Red #36 is a typical nonsoluble azo color is not recommended for lipstick because of its very slight solubility in oils and waxes it tends to crystallize upon continual reheating of the lipstick mass. Soluble azo dyes such as FD&C Yellow #5 and #6 Red #33 lakes are often used in lipstick and nail lacquer. Sparingly soluble types such as D&C Red #6 are not highly soluble but the barium lake of Red #6 and the calcium

lake of Red #7 are the most popular colors for cosmetics. Colors in this group do not need a substrate to make them insoluble. The D&C Red #6 and #7 lakes are widely used in lipstick and nail lacquer because of high strength, bright hues, good light fasteness, as well as chemical and heat stability. Non-azo-soluble dyes such as D&C Red #21, Orange #5, and Red #27 are all fluoresceins and act as a pH indicator and will change accordingly. They all strain the skin and D&C Red #27 gives the strongest blue stain.

Quality Control of Colorants

Establishment of Standards

• Ensure that product development is performed with material representative of supplier's production

• Before purchase, evaluate at least three lots, establish standard in consultation with the supplier

• Supplier and end user should agree on specifications, standard, and test methods Test Methods

Shade Evaluation. Methods should predict performance of the colorant under use conditions.

Light Source for Visual Evaluations to Be Specified.

• Dyes: Visual or spectrophotometry evaluation of solutions.

• Pigments: Cannot be evaluated as received due to variable degree of agglomeration. Visual or instrumental evaluation is made of wet and dry dispersions prepared under defined conditions to a defined degree of dispersion.


Dispersion equipment:



Nitrocellulose lacquer

Hoover muller,

Acrylic lacquer

Three roll mill, or

Castor oil

Ball mill

Heavy Metals: Wet chemical

Atomic absorption spectroscopy (AAS) Inductive coupled plasma (ICP)

Particle Size:

Wet/dry sieve analysis Optical microscopy Laser diffraction Sedimentation

Bulk Density:

Fischer-Scott Volumeter pH

Pearlescent Pigments and Other Specialty Pigments

Pearlescent Pigments:

The most important requirement for a substance to be pearlescent is that its crystals should be plate-like and have a high refractive index. A thin, transparent, platy configuration allows light to be transmitted. A pearlescent material should have a smooth surface to allow specular reflection and be nontoxic. Generally, when using pearlescent pigments one must use the most transparent formulation, avoiding grinding or milling the pearl pigments and blend pearls complement one another.

1. Organic Pearls. These pearls produce a bright silver effect and are obtainable from fish scales as platelets or needles, which are highly reflective. The materials responsible for the pearl effect are crystals of a purine called guanine. Guanine is chiefly used in nail-enamel.

2. Inorganic Pearls.

(A) Bismuth oxychloride:

Bismuth oxychloride produces a silvery-grey pearlescent effect and is synthesized as tetragonal crystals. Crystal sizes vary from approximately 8 microns, which give a soft, opaque, smooth luster, and 20 microns, which give a more brilliant sparkling effect. Its major disadvantage in use is poor light stability, which may cause darkening after prolonged exposure. UV absorbs in the finished products are used to overcome this defect. BioCl is chiefly used to pearl nail enamels, lipsticks, blushes, and eye shadows. BioCl may be modified by deposition on mica, titanium dioxide and mica, or talc. Inorganic pigments may be bonded to BioCl then deposited on mica. All these alter the final effect on the finished product.

(B) Titanium dioxide-coated micas:

Titanium dioxide-coated micas are extensively used in decorative cosmetics. They exist in several different forms: (1) silver-titanium dioxide uniformly coats platelets of mica, rutile crystals give a brilliant pearl effect because of a higher refractive index than the anatase grade; and (2)interference pearlescent products can be made by altering the thickness of the film. At a certain thickness, interference of light can take place so that some wavelengths of the incident light are reflected and others transmitted. The colors created are complementary to each other. As the layers become thicker, the reflection goes from silvery white, then yellow-gold, red, blue, and green. Additionally, colorants such as iron oxides can be laminated with this interference film, providing a two-color effect.

3. Pigment Pearls. Colored pearls are produced by laminating a layer of iron oxides on titanium dioxide-coated mica, producing a color and luster effect.

4. Specialty Pigments. In addition to BioCl and the titanium dioxide-coated mica systems, polyester foil cut into regular shapes, which have been epoxy coated with light fast pigments, have been used for nail enamels and body makeup. Finally, aluminum powder and copper/bronze powder have been used as reflective pigments, especially in eye shadows. For cosmetic-use aluminum powder, 100% of the particles must pass through a 200 mesh screen, and 95% must pass through a 325 mesh (44 millimicron) screen.

Treated Pigments

Surface-treated colors and substrates allowed chemists to enhance the aesthetic and functional qualities of their formulations. The benefits of using these treatments may be divided into two categories: those evident in the finished cosmetic product, and the benefits derived from process improvements. Consumer benefits include hydrophobicity yielding greater wear, improved skin adhesion, smoother product feel, improved optical appearance, moist-urization, and ease of application. Processing benefits include ease of dispersion, pressabil-ity, less oil absorption, uniformity, and less moisture absorption. The following surface treatments are commercially available:

• Amino Acids (N-Lauroyl lysine, acyl amino acid [11])


Good skin adhesion pH balanced Heat sensitive

• Fluorochemical (Perfluoropolymethylisopropyl ether perfluoroalkyl phosphate)

Hydrophobic and lipophobic greatly enhance wear Heat and shear resistance


Exceptionally smooth, silky skin feel, particularly in pressed products Heat sensitive, slightly soluble in water

• Metal Soaps (ZnMg Stearate)

Good skin adhesion Enhanced compressibility


Moisturizing skin feel Good skin adhesion Heat sensitive (low m.p.)

• Nylon (pure mechanically coated)

Smooth skin feel

• Polyacrylate

Enhanced wetting in aqueous systems

Feel is not very good but is usually used in dispersion

• Polyethylene

Hydrophobic Waxy, smooth skin feel Enhanced compressibility Heat sensitive

• Silicone (Polymethylhydrogensiloxane; methicone will be chemically bonded g and cannot be removed later)

Hydrophobic <y

Achieves full color development Main use is to improve wetting

• Other Silicones (No potential for hydrogen evolution) s

Dimethiconol 2

Absorbed dimethicone Silicone/lecithin

Extremely hydrophobic, lipophilic No hydrogen potential

• Titanate Ester Isopropyl triisosteryl titanate [13]

Enhances wetting in oil Smooth skin feel High pigment loading Lowers oil absorption of pigments

Microfine/Ultrafine/Nanosized Pigments

These pigments have a primary particle size below 100 nm; larger agglomerates/aggregates can be present. Properties such as surface area, bulk density, vehicle absorption, and UV absorption differ significantly from those of conventional pigment. Microfine titanium dioxide, zinc oxide, and iron oxides can be used in a range of color cosmetics to provide unique visual effects as well as UV protection. In pressed powders and anhydrous and emulsified formulations, significant SPF values can be achieved in formulations having a translucent, natural-looking finish. With microfine pigments, formulations for darker skin tones can be formulated that avoid the ''ashy'' or ''made-up'' appearance caused by conventional opaque pigments.

Light-Diffusing Pigments

Some of the requirements for light-diffusing pigments include a high refractive index, reflection to be diffused, translucency, and its transmission must be primarily diffuse. Skin has a refractive index of 1.60. Examples of light diffusers include BaSO4, silica, silica spheres coated on mica, TiO2/BaSO4-coated mica, Al2OH3/mica, ultrafine TiO2/mica, ultrafine TiO2/polyethylene, ethylene acyrates copolymer, polymethyl methacrylate, among others. These products are chiefly used in powders to create illusions and hide wrinkles.

11 Habits To Make or Break For Soft Flawless Skin

11 Habits To Make or Break For Soft Flawless Skin

Habits to Break and Habits to Maintain for Dazzling Skin. As you all know, our skin is the obvious appearance of who or what we are, or perhaps would like to be. However, it is more than just a simple mask.

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