Article by: Kelly Dobos
The incorporation of color in cosmetic and personal care products is part art and part science. What seems like a simple and fun exercise in pigment blending is reliant on a complex set of decisions. The regulatory environment, cost, stability, physical and chemical properties all play a role in determining success. Here are a few rules to help guide the choice of colorants used in formulation.
Color Selection Rules
1. Always Review Color Regulations First – Be sure to review the regulatory requirements for the areas in which the products will be marketed and sold. Requirements vary by colorant and there can be restrictions on end use application (e.g. restricted from eye area) and percentage.
2. Keep in Mind Stability and Formulation Limitations – Some pigments are fugitive to light and may need a good UV absorber or opaque packaging, others are sensitive to pH or heat. A good product technical data sheet will make note of these limitations. Review in advance to avoid surprises.
3. Always Use Multiple Color Additives – Cosmetic and toiletry products are rarely formulated with a single color additive. There are almost always three of them used and sometimes, considering the use of effect pigments, as many as six or seven. There are two important reasons for use of multiple colorants. First, there are shade differences from batch to batch of the same color additive. So, having more than one of them in a formula allows for adjustments in their ratios to produce a finished product with the exact same shade every time. Second, the use of several different colorants makes copying the product by a competitor much more difficult.
4. Avoid Color Extremes – The use of color additives with extreme differences in shade are normally avoided. Mixing these extremes can result in a dirty appearance in the final shade.
5. Try Different Color Combinations When Looking for Cost Efficiencies – There are big differences in the costs of color additives and there is often more than one combination of them that will result in a particular finished product shade.
6. Oil Absorption is an Important Consideration in Lipstick and Emulsions – The tendency to absorb oil from a formula varies considerably from color additive to color additive. In general, the synthetic organic colors, particularly the aluminum hydrate lakes, exhibit higher oil absorption that the inorganic colorants. This variation requires the chemist to adjust the percentage of oil from shade to shade in a product line. The variation in oil percentage will insure that the stick hardness in lipsticks will be the same throughput the line. It will also insure equal rheology in other liquid oil products and emulsions.
7. Dispersion, Dispersion, Dispersion – I cannot express the importance of dispersion enough. Dispersion is the process of separating colorant agglomerates and distributing them throughout the product. This process is necessary to develop the full tinctorial value from a color additive. Like oil absorption, the ease of dispersion varies from colorant to colorant. For this reason, dispersions of single colorants are easiest to work with.