SKIN CARE 47


widely used in the cosmetic industry to add lustre or sparkle, impart colour or colour- travel effects, and provide coverage. The adjective nacreous is derived from


nacre, which is pronounced NAY-ker. It refers to the material that makes up pearls and the iridescent mother-of-pearl produced in mollusc shells. Several types of cosmetic pearls are available based on different substrates, such as mica, guanine, bismuth oxychloride, and fluorophlogophite. Each substrate has its own advantages and disadvantages. More formally, cosmetic micas are postassium aluminum silicate dihyrdrate. Silicates, much like silica, are based on interconnected SiO4


tetrahedra. However,


in silicates the ratio of Si to O is greater forming silicone-oxygen anions. To form neutral solid silicates, cations like potassium are needed to balance the negative charge. Micas are subject to size restrictions; particles are not to exceed 150 mm. Other substrates are not specifically regulated for particle size. Naturals micas can darken with oil absorption, including sebum from the skin. Guanine, a common biological molecule, is derived from fish scales and provides a soft pearly shimmer. It is the photonic crystalline structure of guanine that scatters and reflects light to produce the pearl effect. Cosmetic grades are, of course, purified and often dissolved in a suitable solvent for ease of handling. Although this might qualify as a true natural pearl, cost is often prohibitive. Though more frequently used as a filler in cosmetic formulations, bismuth oxychloride provides a silvery, white tone. The various particle sizes available allow for different levels of transparency, however larger crystal forms are supplied as dispersion because these larger crystals can be broken in their dry form. Bismuth oxychloride can darken with light exposure and should be protected with opaque packaging. Referred to as synthetic micas,


fluorophlogophites are one of the newest innovations in pigments. Unlike mica, which carries more natural impurities along with it, the synthetic version is cleaner and more transparent. This allows for more brilliant sparkle effects. Pearls are fragile and should not be milled or exposed to harsh mixing. They are truly stir-in ingredients and should be added to formulas late in the process. All pearls need to be suspended in formulation. In emulsion and gel formulas, ingredients like carbomer or xanthan gum can provide sufficient yield value to suspend pearls.


Soft focus effects Soft focus effects help optically blur fine lines and other imperfections, providing an


November 2017


immediate effect after application. Their incorporation into numerous cosmetic and skin care products has grown in not only anti- ageing categories but are now incorporated into makeup primers for everyday use as social media trends continue to drive the desire for a flawless complexion. A wide variety of optical blurring


ingredients have been utilised in cosmetics, such as very small particle sizes of synthetic mica, alumina, polyethylene microspheres, and silicone elastomers. Some of these materials can be cost prohibitive. A composite of talc and titanium dioxide (Spectraflex Illusion) is a new, novel approach to soft focus that is cost advantageous, leading to the possibility that it can even be used in body care to improve the appearance of imperfections like cellulite on thighs.


Soft focus materials balance the scattering of light from the surface of the skin and into the skin.8


Diffuse transmission


is what typically comes to mind when thinking of optical blur. Diffuse transmission is the amount of light that is spread out, away from the source after it passes through an object.


While it seems beneficial, designing materials solely around diffuse transmission is not the most efficient means. The ideal properties for an optical blur effect are a balance of reflectivity and transparency. Both of these traits need to be optimised in both their diffuse and total nature. Reporting diffuse transmission without reference to the total transmission (or overall transparency) can be misleading. Traditional TiO2


diffuses and scatters


light incredibly well, but the overall transparency (total transmission) is too low to be useful in true optical blurring. Balancing reflectivity with transparency is another, paradoxical obstacle. Optical blurring is at its best when there is sufficient hiding to cover blemishes and discoloration


but not overbearing as to create a film or chalky appearance. A high degree of transparency will allow for the natural glow of the skin to show but without diffuse reflectivity, the contrast of wrinkles and creases cannot be hidden. The novel composite of talc and titanium dioxide has been tailored to balance transparency, diffuse transmission, and diffuse reflectivity to achieve the noticeable optical blurring effects.


Conclusion


Utilisation of pigments in cosmetics and skin care is complex. Pigment chemistry and processing play an important role, as well as innovation in surface treated pigments and soft focus effects.


PC


Refrences 1 Rigano L. Formula Anatomy Deciphered: Color Foundation and Base Formulas. Cosmetics & Toiletries 2012, online.


2 Tsolis P, Castro J. Troubleshooting Stability, Uniformity in Foundations. Cosmetics & Toiletries 2012; 127(3): 158.


3 Faulkner EB. Coloring the Cosmetic World: Using piments in Decorative Cosmetics Formulations. Carol Stream, IL: Allured; 2012.


4 Hollenberg J. Color Cosmetics: A Practical Guide to Formulations. Carol Stream, IL: Allured; 2016.


5 O’Lenick A, Klein K, Lavay C. Triglycerides with Unusual Components. Oils of Nature. Carol Stream, IL: Allured; 2008, 71-80.


6 Thiemann SG, Salima-Petersen M, Janiche J. Wetting Agents - Multifunctional Ingredients in Color Cosmetics. SOFW 2015;141(9-2015):34-40.


7 Faulkner EB, Zavadoski, WJ. Pigment Surface Treatments: A Bench Chemists Guide. Cosmetics & Toiletries 1994; 69-72.


8 Deckner G. Soft Focus Technology 2014 [8/24/2017]. Available from: https://knowledge.ulprospector.com/692/pcc- soft-focus-technology/.


PERSONAL CARE ASIA PACIFIC


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