Type of Colorant
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.
Many materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at ambient temperatures.
For industrial applications, as well as in the arts, permanence and stability are desirable properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, while some eventually blacken.
Pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food and other materials. Most pigments used in manufacturing and the visual arts are dry colorants, usually ground into a fine powder. This powder is added to a vehicle (or binder), a relatively neutral or colorless material that suspends the pigment and gives the paint its adhesion.
A distinction is usually made between a pigment, which is insoluble in its vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution). A colorant can act as either a pigment or a dye depending on the vehicle involved. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment. The term biological pigment is used for all colored substances independent of their solubility.
"Natural" and "Certified Organic" colors
So called “Natural” colors must be approved by the FDA for use in edibles, cosmetics and drugs, but are not subject to batch certification. Examples of "Natural" colors are beet , paprika , annatto, turmeric, titanium dioxide, caramel and cabbage to name but a few. It is important to note that there is no FDA definition of "Natural" with reference to food or ingredients.
The USDA’s National Organic Program certifies products as organic based on farming, handling, manufacturing, distribution and labeling practices. Certified Organic Colors are a select group of Natural Colors that contain ingredients that are in compliance with the USDA National Organic Program and which have been certified by an independent organic certification agency.
Colors used for Cosmetics
The color pallet for cosmetic products is broader than that available for food color. There are a wide variety of “D&C” Dyes and Pigments that can be used in cosmetics and drugs, but are not suitable for consumption. In addition, there are a wide array of pigments such as Iron Oxides and Ultramarines that do not require certification that can also be used in cosmetic products.
The dispersing mediums available for use in Cosmetics are much more varied than those available for edible products. Ingredients such as castor oil, mineral oil, and silicone can be used in cosmetics, but not foods.
Dyes vs. Pigments
Dyes dissolve in liquids. This gives them the ability to stain porous materials such as cloth or wood. They also tend to be very bright and produce transparent colors which don't separate but are strong bleeders. Dyes are notorious for being fragile when exposed to light and can react to pH changes. They can also react to salt, which is why some use the hybrid Lake colors instead.
Pigments do not dissolve but instead disperse as very fine particles. They have very limited staining power on their own and need an additional binder to make the particles adhere once the liquid medium has evaporated or dried. Pigments are more deep than bright and produce more opaque colors that will separate over time but do not bleed. They are also quite stable when exposed to lights, pH differences and chemicals.
The difference between (True) Dyes and (Hybrid) Lakes
A DYE is a distinct chemical that exhibits coloring power when it is dissolved. Dyes are water soluble, and will not mix with oils. Dyes can be purchased in a Powder format or a less dusty version called "Granular".
An ALUMINUM LAKE PIGMENT is an insoluble material that tints by dispersion. Lakes are produced from the FD&C Dyes and are oil dispersible (but generally not oil soluble) and thus can be mixed with oils and fats. They can also be dispersed or suspended in other carriers such as propylene glycol, glycerin and sucrose (water and sugar).
Lakes are produced in specific concentrations of dye. Thus, Red 40 Aluminum Lake is available in Low Dye (generally 15-17% pure dye) and High Dye (36-42% pure dye).
Because they are a hybrid of a pigment and a dye the pigment portion will tend to separate out of a material while the dye does not and tend to be more stable to light, pH and other factors than true dyes.
Many cosmetic mineral pigments have been treated with radiation as a safeguard against bacteria. Companies like Vapour Organic Beauty has gone to great expense to source pure mineral pigments that have been heat treated as an anti-bacterial measure, and NOT irradiated. Yay Vapour!