Introduction
Light dances on the surface of special effect pigments before it bounces off angles to bend and blur lines with optical diffusion, creating depth, offering dimensionality, sheer luminous glow or a dazzling, eye catching sparkle. Used in everyday products across a wide array of industries such as color cosmetics, personal care, auto, paint and fashion, an effect pigment can display color, offer multiple effects, impart color travel as it reflects and refracts light through many angles. The chemistry and manufacturing process impact the unique visual performance of these special effect pigments but may not be as appreciated or understood compared to the end product’s desirable effects. Taking a closer look at the use of effect pigments in the beauty industry as their function and use allows for eyeshadows to take on properties offering intense color depth and a captivating sparkle, stunning gemstone effects in nail polishes and for highlighters to impart a soft focus contour on cheek bones.
The special effect pigment market has been forecasted to increase over the next 5 years due to high consumer demands seeking to continue personal care upkeep particularly within the nail and eye category as a result of Covid-19. An evolution is not only seen regarding effect pigments usage through the years in cosmetic products to attain desired results, but also with an important transition to address sustainable platforms looking to safeguard global resources. These initiatives intertwine the beauty industry with heightened levels of innovation to support ethical and environmental objectives.
Intricate Composition
Special effect pigments, often referenced as pearlescent pigments, have manufacturing processes that are as dynamic as the product effect itself. Visual properties are created with a starting base layer known as a substrate. Initial determination between a natural or synthetic substrate help to establish expected properties and unique characteristics when used in a product. Natural options include Mica, Kaolin, and Rayon. These ingredients are Generally Recognized as Safe (GRAS) and create similar effects to synthetic options such as fluorophlogopite, boron nitride, and glass flakes/borosilicates. Differentiation is demonstrated through optical impressions with the level of reflection, opacity, and interference offered.
Depending on the selected substrate and desired end use, the manufacturing process plays a critical role to yield the product consumers are accustomed to seeing in finished goods. Review of the process cycle used when mica is the substrate offers an opportunity to demonstrate the level of detail involved during development. The mined mica is coated typically with Titanium Dioxide or oxide metals during processing. This occurs when a base and acid are combined in a reactor used to calcine the substrate at variable high temperatures. Impurities are then filtered off, and the process is completed through blending. The thickness of the coating on the substrate directly determines elements of color and can offer interference effects when alternating layers of oxide metals are used or combined with transparent spacers to create optical variable pigments for color travel. Observed color effects are directly correlated to the thickness of the coating as it increases and decreases. The thickness of the coating impacts color development ranging from gold, red, violet, blue to green translating from 70 nm to 360 nm in measurement, respectively. Particle size of the effect pigment plays a critical role as well in the brilliance. Smaller sizes closer to 10 µm impart more of a soft texture matching a satin sheen coverage; larger sizes closer to 60 µm displays more of a dazzling pearlescent appearance; while an average micron size of 125 and above sparkle.
Enhancements
Effect pigments similar to iron oxides and dyes are not necessarily easy to add to formulas as it is dependent on the chassis composition. Stability, color shift, and undesirable payoff performance can be experienced by a formulator during product development as a result of polar hydroxyl groups with adsorbed moisture on the effect pigment. Surface treatments on effect pigments whether physical or chemically added can address many common drawbacks to ease dispersion into formulas, improve outcome of stability and other unique benefits based on the chemical properties of the specific treatment used.
Sustainable Vision
Ethical and environmental concerns prompted many forward-thinking beauty organizations to create innovative solutions and restriction lists in response to negative aspects of the effect pigment supply chain. Focus on child labor, traceability, and environmental considerations are needed for a better tomorrow to keep our world beautiful more than just on the surface. As a result of these issues being uncovered, opportunities arose for alternative material solutions paired with philanthropic initiatives to give back to communities. As a result, demand to innovate in support of environmentally considerate substrates such as bio-based options were developed. Bio-based effect pigments look at upcycling to introduce cleaner alternatives with similar appearances and attributes especially compared to PET glitters. The ban on microplastics in recent years has exposed PET glitter due to their small size and inability to breakdown as they enter the environment and can end up on our dinner tables. Due diligence has spurred innovation on many levels as formulators seek new understandings to develop similar product effects and encourage consumer education in hopes to inspire mindfulness.
Formulating Tips
- Effect pigments should be incorporated carefully into batches and sweep mixing blade is recommended. It’s best to avoid particle size optimization with homogenizers as they are fragile materials, and it jeopardizes the effect of larger micron sizes when sheer force is applied. When the effect pigment surface is deformed the sparkle effect is reduced or no longer visible.
Take time to understand the material’s specifications from the certificate of analysis (COA). For example, when formulating anhydrous formulas the oil absorbency and ingredient ratios determine ease of pourability, skin feel, and payoff. A balanced, high performing formula takes into consideration these aspects to make improvements and/or alternatively to select a surface treated option if a high effect pigment loading is required. - Caution is recommended with composites that contain Ferric Ferrocyanide, Carmine or when used in a formula that will contain Avobenzone with Titanium Dioxide coated pigments as this will likely shift color and cause other adverse stability outcomes.
- Understand global regulations to ensure that each of the effect pigment constituents meet regulatory requirements and areas of use for distribution. Not all pigments are allowed in the eye area and micron size is another critical aspect to consider pending product positioning. Generally, special effect pigments for eye product have a micron cap at 150. While this can pose as a challenge to match prototypes there are other available options such as synthetic fluorophlogopite that do not follow the same particle size restrictions.
- Color matching should be done with colorants, iron oxides and dyes, then to use effect pigments to compliment. Higher usage levels of pigments should be used to achieve deeper, more intense tones and will offer a good base color to make it easier to shade match instead of being reliant on pearls alone where there is less color consistency. This technique promotes cost efficiency for a more economical approach to shade matching as well.
Conclusion
Special effect pigments have wide applicability to impart visually appealing impressions. The characteristic properties are heavily reliant on the chemical framework and manufacturing process implemented to determine desirable elements. The beauty industry counts on effect pigments for their role to enhance the color appeal, effects, and texture in finished goods. Even as much as the consumer looks for these alluring effects, sustainable platforms are necessary as awareness increases. Sustainability has invigorated innovation within this market that will hopefully continue to support technological advances with novel solutions.
References
- Cramer WR. Hidden Secret of Effect Pigments. PCI Magazine, October 3, 2017 – https://www.pcimag.com/articles/102924-hidden-secrets-of-effect-pigments
- Maile FG, Pfaff G, Reynders P. Effect pigments-past, present and future. Progress in Organic Coatings, 54 (3): 150-163, 2005
- Special Effect Pigments Market Size 2020 Industry Demand, Share, Trend, Industry News, Growth, Top Key Players, Business Statistics and Forecast to 2026. Market Watch, October 8, 2020.
Acknowledgements
Frank Mazella, David Schlossman, and Yun Shao for inspirational talking.
Stacey House
Stacey is the Vice President of Research and Innovation at KDC/One’s East Coast R&D leading the talented teams at Acupac, Chemaid, Innovation Lab and Kolmar. Her strong team is focused on developing elevated, high touch formulas in categories spanning the personal care industry. Previously, she was the Director of R&D at Mana Products, Director of Applications at Kobo Products, and had also worked in Coty and Revlon’s R&D labs. She holds a patent on Low Viscosity Phenyl Trimethicone Applications and has written several published industry articles. Stacey graduated from Northeastern University with MBAs in Operations, Supply Chain, and International Business and received her Bachelors of Science degree at Rutgers University-New Brunswick.