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Multifaceted Dimensions of Special Effect Pigments

by james.runkle@drummondst.com james.runkle@drummondst.com No Comments

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

  1. Cramer WR. Hidden Secret of Effect Pigments. PCI Magazine, October 3, 2017 – https://www.pcimag.com/articles/102924-hidden-secrets-of-effect-pigments
  2. Maile FG, Pfaff G, Reynders P. Effect pigments-past, present and future. Progress in Organic Coatings, 54 (3): 150-163, 2005
  3. 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.

 

A Journey into Color Cosmetics and Lip Product Development

by james.runkle@drummondst.com james.runkle@drummondst.com No Comments

Introduction

The birth of color cosmetics is said to be traced back all the way to Mesopotamia over 5000 years ago where gems and semi-precious gems were ground up and applied to both the lips and the eyelids. In 4000 BCE, Egyptian women would apply Mesdement, a dark grey ore of lead, Galena chemically known as Lead Sulfide, and Malachite (bright blue green paste of Copper minerals) to color their faces for color. They also extracted color from seaweed, Iodine, and beetles to further add to their makeup palette. (1) Somewhere around 3000BCE women in in Greece applied a paste to their face consisting of white chalk, or lead, mixed in with crushed fruits such as Mulberries. They also used lipsticks comprised of clays mixed with red Iron.(1) During the Renaissance Era it was recorded that women use Arsenic in their face powders to replace lead and it wasn’t until the early 1800s that both of these were replaced by what is commonly known today as Zinc Oxide. In 1894 we saw the birth of what is known today as the PCPC, or Personal Care Products Council. Soon thereafter and beginning in the 1900’s the world saw a rapid increase in popularity of color cosmetics as well as the conception of many cosmetic companies commonly known today such as L’Oreal, Max Factor, Avon, and Maybelline to name a few. With this surge came new product forms such as hair dye, mascara, the first liquid nail polish, the powder compact, and in 1928, the very first lip gloss. In the 1940’s leg makeup was developed out of a need of necessity to fulfill the shortage in stockings due to World War II. Over the course of the next 60-70 years the beauty industry would experience a rapid growth spurt in not just technology but also in regulatory bodies that formed the very foundation for what our industry is today.

Color Ingredients

When we speak of color cosmetic formulations, the primary desired end benefit of these products is the same as it was thousands of years ago and that is to impart color to a part of the face to enhance one’s beauty and feel good about oneself. Whether it be a lipstick, foundation, concealer, eye shadow or pressed powder, the color additives are the main constituent and the base formula is what delivers the color and differentiates the product form. These color additives typically consist of pigments, lakes, dyes, and mica and their differences are explained below:

Pigments– Insoluble particles that impart a color to a product. Inorganic pigments are derived from minerals and have good stability to heat and light. Organic pigments, by nature, are carbon based and tend to have a brighter appearance to them. Commonly, pigments are often surface treated and sold in dispersions of various esters and oils to facilitate ease of use in manufacturing and ensure homogeneity of the color.

Lakes– Produced through precipitation of FD&C soluble dyes with metallic salts such as Aluminum salts. Lakes are useful to extend the color range of a shade palette. These ingredients are often surface treated and sold in dispersions of various esters and oils to facilitate ease of use in manufacturing

Dyes-Predominantly water-soluble, these ingredients are used in skin care, body care, fine fragrance, hair care, and color cosmetics. There are some dyes that are oil soluble as well.

Mica– A name given to a group of silicate materials that are used to add shimmer and sparkle

 

Even though all the ingredients above can be used across the broad category of color cosmetics from eye shadow and pressed powders to lipsticks and foundations, for the purposes of this article we will focus solely on the formulation of lipsticks and liquid lip products.

Physiology of the Lips

The physiology of the lips plays a key role when developing lip products. By nature, the lips are thinner than the skin on the rest of your body and therefore are more sensitive to changes in temperature and texture of a product. Therefore, comfortability and wear are 2 key product parameters that must be properly balanced during development. The lips also do not have hair follicles or oil glands and as a result of this are more prone to drying out especially in the winter months or in low humidity climates. As a result of this, key benefit claims such as hydration and intense moisturization are common for this product type. Finally, the lips do not contain melanocytes found in the skin and as such the color from the lips comes from the blood vessels directly under the surface of the lips.

During aging the lips begin to undergo biological changes like that around other parts of the face and body. The shape of the lips begins to become narrower and longer. They begin to lose volume and color overtime making them appear paler and less vibrant in color and the lines on the lip surface begin to deepen often causing the unwanted side effect of bleeding and feathering. Furthermore, they often present themselves with an unsmooth color tone and appearance.

Environmental exposure can also cause premature aging and thinning of the lips. Chronic UV exposure causes a breakdown in the collagen making the lips appear less full and voluminous. Dehydration from extreme weather conditions or poor health habits can lead to premature and undesirable chafing while exposure to environmental pollutants, i.e., free radicals, and smoking can lead to premature lip lines above the top lip.

Lip Product Formulation

Given the sensitivity of the lips and the desire to keep them young and vibrant looking there are multiple lip products out on the market today each with their own unique benefits and performance. Typically, colored lip products are found in 4 distinct anhydrous forms:

  1. Lipsticks
  2. Liquid Lipsticks
  3. Lip Gloss
  4. Lip Balms

Traditional lip formulations are composed of emollients, oils, waxes, and colorants with the ingredient ranges varying to deliver a stick or liquid format. Emollients/natural oils such Castor Oil, Lanolin, Shea Butter, are primarily used to help disperse colorants, while providing moisture and smooth application. Structuring agents such as Ozokerite, Polyethylene, and Carnauba and gellants are often used to give the sticks rigidity and stability while film formers are often utilized to improve the transfer resistance and wear properties. Benefit ingredients such as vitamins, natural oils, Hyaluronic acid, fragrance, etc. can all be added as well based on the target audience and desired claims.

In terms of finish, lip products typically are found in multiple styles ranging from matte, satin, pearl and shine with sheer to full coverage levels. From a performance perspective, today’s products are a great evolution to those from a century ago offering intense, continuous hydration, waterproof and transfer proof properties, SPF protection, and even all-day long wear.

Conclusion

Over the years the line between color cosmetics and skin care has become less defined. While the primary function of a color cosmetic is to provide color to the face, lips and eyes, the formulas themselves have become more technologically advanced and multi-faceted. Today’s products offer the consumer benefits beyond color such as anti-aging (wrinkle reduction), sun protection, anti-pollution, reduction of oily and acnegenic skin, minimization of scars, and even  tattoo and hyperpigmentation coverage. Additionally, companies continue to innovate in new color cosmetic product forms and test methodologies to deliver aesthetically pleasing, high performance products. For certain, this is a space that will continue to not only innovate but also adapt to today’s complex global challenges while pivoting to consumer needs for years to come!

References

  1. https://cosmeticsinfo.org/Ancient-history-cosmetics

 

Authors

 

Peter Konish has been in the industry for 25 years and is currently the Director of the Lip Category, Product Development and Innovation for Coty. Prior to this, he was the Global Director of Technical Operations in the Skin Health division of Johnson and Johnson. In this role Peter was responsible for Process Development, Packaging Development, and External Development/Innovation. Before moving to Technical operations, Peter spent 13 years at NeoStrata in Product Development overseeing the development of numerous Anti-Aging, Prestige Beauty, and Dermatological skin and body care. Peter also spent 9 years at L’Oreal in its Fine Fragrance division working on such brands as Ralph Lauren and Kiehl’s. Peter has a background in polymer chemistry, he has co-authored numerous book chapters and scientific publications, and has been an industry speaker at SCC events and annual AAD meetings.

 

 

Jeanine Smith has been in the industry for 19 years with her core focus in color cosmetics.  She is currently the Senior Manager of the Lip Category at Coty.  Prior to joining Coty, Jeanine was a Senior Manager at Avon Products where she worked in product development for the Eye, Nail and Lip categories.

 

Delivery Systems for Antioxidants

by james.runkle@drummondst.com james.runkle@drummondst.com No Comments

Introduction

As the body’s first defense against the elements, skin is frequently exposed to electromagnetic radiation from the Sun, which can lead to a variety of detrimental conditions such as photoaging, photoimmunosuppression, and photocarcinogenesis. Reactive oxygen species are largely responsible for the initiation of these disease states in skin and are mostly due to exposure to ultraviolet light, but have also been shown to result to some extent from the absorption of visible and infrared light. Considerable efforts have also been made to better understand the effects of pollution on the skin from a free radical and reactive oxygen species point of view.

Antioxidants

The use of antioxidants in various skin treatments is a sound approach to improve the overall health state of skin [1]. This statement is supported by a wealth of research conducted over the last several decades toward better understanding how antioxidants mitigate the effects of solar radiation. Topical application of antioxidant-containing products reduces the deleterious effects of solar radiation exposure of the skin.

While some antioxidants may offer some photoprotection as a solar filter, the majority of their mechanisms are through their antioxidant capacity or immunomodulating effects. Some of the most common antioxidants in skin care formulations are vitamin E, vitamin C, and coenzyme Q. Historically, these were probably the most studied antioxidants due to their importance in the endogenous antioxidant system.

Equally important are a vast majority of botanical extracts, which are chock-full of phyto-antioxidants. In recent years, research has focused on understanding the antioxidant behavior of polyphenols in an attempt to harness their protective properties for skin. In some cases, specific polyphenols are used in formulation while in others the extract is directly added.

 

Topical Application of Antioxidants

Topical application of antioxidants is the most straightforward approach to fortify the skin. As compared to dietary intake of antioxidants, in many cases topical application allows: (1) greater concentrations to reach tissues, (2) greater tissue specificity, and (3) reduced side effects to other organs. Unfortunately, not all antioxidants (e.g., from extracts) easily cross the stratum corneum barrier. The fact that some antioxidants are not able to penetrate the skin could be considered a positive toxicological benefit. Skin permeation and antioxidant stability can be enhanced by utilizing state-of-the-art delivery systems.

One of the major factors with antioxidant stability in skin care formulations stems from the need to prevent oxidation within the formulation and also to deliver to the skin an active antioxidant that is bioavailable. In many cases, formulations are based on carrier systems in which oxidation can occur in the oil phase, water phase, or at the interface. More often than not, oxidation occurs at the interface. Some of the hurdles facing formulators in the antioxidant arena are a result of stability issues with antioxidants that are intended to be delivered to skin.

 

Antioxidant Carrier Systems

The use of carrier systems represents a real asset for the delivery of antioxidant to skin and can include various types of emulsion, vesicular, or lipid particle systems.

Emulsions systems

These systems are dispersions of oil and water and can refer to microemulsions, nanoemulsions, and Pickering emulsions. Microemulsions and nanoemulsions are characterized by the dispersion size of the emulsified phase, while Pickering emulsions refer to a type of emulsion that is stabilized by solid particles.

Vesicular systems

These systems consist of liposomes, phytosomes, transferomes, ethosomes, and niosomes. Liposomes are the most popular vesicular system used in personal care applications and are composed of concentric layers of phospholipid bilayers spherically shaped with a hollow center for the active ingredient. Phytosomes are vesicles of phospholipids that have high affinity for phytocompounds, such as polyphenols. Transferosomes are lipid vesicles that consist of fatty acids and a small amount of ethanol. They are more elastic than liposomes, which improves their deposition characteristics. Ethosomes are lipid vesicles that contain even greater amounts of ethanol, yielding a more flexible vesicle. Niosomes are lamellar vesicles based on nonionic surfactants. Due to the nature of the surfactants in niosomes, crossing the stratum corneum is more facile than in the case with other vesicles.

Lipid particle systems

These systems consist of lipid microparticles and lipid nanoparticles. Lipid microparticles are created by a process known as microencapsulation where a small solid or liquid droplet is surrounded with a thin layer of shell. Lipid nanoparticles are further categorized as solid lipid nanoparticles and nanostructured carriers. Solid lipid particles consist of a lipid system in the solid state at room temperature with a thin surface coating on the outside as a stabilizer. Nanostructured lipid carriers, on the other hand, are more complex and contain lipids both in the solid and fluid phase. Typically, such systems can increase the stability of antioxidants and their permeation efficacy to skin as well as reduce irritation. The reader is referred to a review by Pol and Patravale for a nice introduction to the subject [2].

 

Nanoparticle and Nanocarriers

Nanoparticles and nanocarriers continue to be at the forefront of skin care research for their potential at stabilizing and delivering antioxidants to the skin. For example, gold nanoparticles are known for their anti-inflammatory, antiaging, and wound healing properties in skin care. A recently published study demonstrated how polyphenols from an aqueous extract can be used to reduce metal salts—in this case gold—into nanoparticles [3]. In another study, gold nanoparticles wrapped with chitosan were used to stabilize ellagic acid [4]. In both cases, green technology was used to fabricate the nanoparticle structures.

Nanoencapsulation is another area that shows much promise for the delivery of antioxidants to skin. Lipid-core nanocapsules containing resveratrol and lipoic acid have enhanced chemical stability and photostability as compared to the non-encapsulated forms of the molecules [5]. TiO2 is a nanoparticle found in many sun protection products. It functions by scattering incoming UV rays from the Sun and preventing photodamage to the skin. Researchers at Sabanci University in Istanbul found enhanced cellular penetration and antioxidant properties of quercetin-TiO2 nanoparticles, as compared to quercetin alone, in studies carried out on fibroblast cell cultures [6].

 

Concluding Remarks

Some of the challenges with the conventional delivery of antioxidants stems from their poor solubility, limited shelf-life stability, compromised photostability, and low degree of skin permeability. Delivery systems enhance the ability of antioxidants to carry out their function. Conventional systems used to deliver antioxidants consist of emulsion, vesicular, or lipid particle systems. In recent years, a great deal of interest has evolved in using nanoparticles as stabilization enhancers and delivery agents for antioxidants. Nanoencapsulation also offers much promise and has been shown to enhance the chemical stability and photostability of antioxidants.

 

References

  1. McMullen, R., Antioxidants and the Skin. 2nd ed. 2019, Boca Raton: CRC Press.
  2. Pol, A. and V. Patravale, Novel lipid based systems for improved topical delivery of antioxidants. Household and Personce Care TODAY, 2009(4): p. 5-8.
  3. Haddada, M., et al., Assessment of antioxidant and dermoprotective activities of gold nanoparticles as safe cosmetic ingredient. Colloids Surf B Biointerfaces, 2020. 189: p. 110855.
  4. Gubitosa, J., et al., Multifunctional green synthesized gold nanoparticles/chitosan/ellagic acid self-assembly: Antioxidant, sun filter and tyrosinase-inhibitor properties. Mat Sci Eng C, 2020. 106: p. 110170.
  5. Davies, S., et al., Simultaneous nanoencapsulation of lipoic acid and resveratrol with improved antioxidant properties for the skin. Colloids Surf B Biointerfaces, 2020. 192: p. 111023.
  6. Birinci, Y., et al., Quercetin in the form of a nano-antioxidant (QTiO2) provides stabilization of quercetin and maximizes its antioxidant capacity in the mouse fibroblast model. Enzyme Microb Tech, 2020. 138: p. 109559.

 

Roger L. McMullen, Ph.D. – BIO

Dr. Roger McMullen has over 20 years of experience in the personal care industry with specialties in optics, imaging, and spectroscopy of hair and skin. Currently, he is Principal Scientist in the Material Science department at Ashland Specialty Ingredients G.P. Roger received a B.S. in Chemistry from Saint Vincent College and completed his Ph.D. in Biophysical Chemistry at Seton Hall University.

Roger actively engages and participates in educational activities in the personal care industry. He frequently teaches continuing education courses for the SCC and TRI-Princeton. In addition, Roger is an Adjunct Professor at Fairleigh Dickinson University and teaches Biochemistry to students pursuing M.S. degrees in Cosmetic Science and Pharmaceutical Chemistry. Prior to pursuing a career in science, Roger served in the U.S. Navy for four years on board the USS YORKTOWN (CG 48). He is fluent in Spanish and Catalan.

 

Formulating effective and stable W/O emulsions

by james.runkle@drummondst.com james.runkle@drummondst.com No Comments

Cosmetic chemists are an innovative, curious, and creative group of scientists, continually looking to formulate the most effective and pleasing products for the world’s consumers. Yet when asked to create the galenic forms most often requested by marketing – creams and lotions – the “default emulsion” is almost always oil-in-water (O/W). While O/W systems offer good sensory properties and ease of manufacturing, the primary alternative system – water-in-oil (W/O) – offers distinct advantages, among them long-lasting adherence to the skin and improved water resistance. So why isn’t W/O used more often? Because (a) it is difficult to create a stable W/O system, and (b) the esthetics of a W/O emulsion are often undesirable (sticky, tacky, thick…).

Let’s cover some key concepts to enhance stability when formulating W/O emulsions:

  1. When making W/O emulsions, high energy is required

Why do we need high energy when making a W/O emulsion? High energy brings several benefits to your W/O system, altogether contributing to a stable emulsion:

  1. Creates high energy dissipation rates 1,2
  2. Controls particle size of the dispersed phase of the emulsion 1,2
  3. Reduces interfacial tension 1,2

To achieve the desired results, one may use high-energy equipment such as a rotor stator/homogenizer or a deflocculator at moderate to high shear.

Let’s take a closer look at each…

A) Dissipation rate refers to the rate of conversion of turbulence into heat by molecular velocity.

Here is a simplified energy flow chart when you are creating a W/O emulsion:

Turbulence, initiated by the high-shearing rotor stator, transfers its energy into kinetic energy within the W/O system. That energy of motion is converted into the large velocity gradients of the dispersed droplets of various sizes. And finally, the energy of the rapidly moving particles is converted into heat through dissipation.2

This is a very simplified flowchart, as there are many other variables involved, but the take-home message here is that the higher the conversion of energy into heat, the higher the dissipation energy, the more kinetically stable emulsion. Essentially, we do not want any energy left in the emulsion, especially in those water droplets because that can lead to instability.

B) The energy applied when creating a W/O emulsion affects the particle size of the internal phase of an emulsion.

As mentioned before, high energy processes will use rotor stators/homogenizers, while a low energy process may use simpler blades (turbine stirrer, propeller, or blade stirrer). If you use high energy, you will achieve a finer, more evenly dispersed emulsion, which is exactly what you want, as this is more stable.

But if homogenization is too mild, due to your equipment and/or shearing speed, your W/O emulsion will be highly poly-dispersed, meaning, there will be a wide size distribution in the dispersed droplets, which can lead to instability. 

C) And finally, we need to use high energy with W/O systems because it reduces the interfacial tension (energy present at the water-oil interface).

This benefit is a result of the other two: The more heat that is given off, the less energy and mobility in the dispersed water phase. And the smaller the average droplet size of the dispersed phase, the more the stability increases. Altogether, there is less energy remaining at the water-oil interface, so water droplets are less likely to coalesce and will remain stable within the continuous oil phase. 

  1. Electrolytes must be used

Electrolytes – inorganic salts such as magnesium sulfate or sodium chloride – must be present in the emulsion because they will stabilize your system through various mechanisms of action. For example, NaCl has been shown to decrease the particle size through electrostatic and steric repulsion in the droplets.3 CaCl2 has proven to decrease attractive forces between water droplets.3 And MgCl2 can reduce interfacial tension and enhance interfacial film strength.3

Each of these mechanisms may prevent one or more of the following from happening.

1) Ostwald ripening, also referred to as disproportionation, is caused by the difference in solubility in emulsion droplets. Smaller droplets are more soluble than larger ones, and with prolonged time, the smaller droplets tend to diffuse in the bulk and are deposited on larger droplets. Therefore, larger droplets eventually grow at the expense of smaller ones. Adding salts will counterbalance the driving force for Ostwald ripening, which is related to the total pressure and pressure in the droplets.3

2) Sedimentation is another unstable condition where there is no change to the droplet size, but droplets move to the bottom. The addition of various salts could improve stability by decreasing particle size and reducing the interfacial tension. Salts can allow for tighter packing of surfactant molecules at the O/W interface.3

3) Coalescence is when droplets join, creating larger sized droplets with water separation at the bottom. Adding salts will reduce the attractive forces between water droplets, which will reduce their collision frequency, and thereby prevent droplet coalescence and increase emulsion stability.3

  1. Depending on the emulsifier, the polarity of the oils used must be specific

Unlike O/W systems, the polarity of the oils used in the oil phase has an outsized influence on the stability of the emulsion, and the performance of high-polarity vs. low-polarity oils will be significant. This is because of the “like dissolves like” rule. In general, chemicals of similar polarities demonstrate better interaction. If the lipophilic tails of your emulsifier are polar, perhaps having esters or hydroxyl groups in its carbon backbone, for example, then the emulsifier is better suited in an oil phase of medium to high polarity. The opposite holds true as well. If the polarity of the oil phase does not match that of the emulsifier, the emulsion will not be stable.

Now, let’s talk briefly about the esthetics of W/O emulsions

W/O emulsions are often tacky or draggy, leaving an unpleasant skin feel and an uncomfortably thick layer of product. Also, as W/O systems are often used with pigments, many common emulsifiers do not have the correct compatibility with the wide variety of pigments used today, resulting in non-homogenous dispersions of the pigments within the emulsion. Many traditional W/O emulsifiers were not designed to address issues of skin feel or pigment dispersion, but modern advances in esterification chemistry allow for the creation of a new generation of emulsifiers that provide perceptibly improved sensory characteristics.

It can be suggested that the use of an emulsifier based on polyglycerol chemistry is especially suited to W/O systems due to enhanced stability resulting from large polar headgroups. (Incidentally, polyglycerol chemistry is considered “green” and advantageous when formulating natural or clean products…) Esterifying a polyglycerol backbone with other esters will significantly effect both skin feel and pigment dispersion properties; for example, the use of a ricinoleic acid ester could provide fluidity and improved skin feel, while the use of a hydroxystearic acid ester could improve the dispersibility of both coated and uncoated pigments.

With these concepts in mind, formulating a W/O emulsion can result in an elegant product satisfying the end consumer while meeting the requirements of marketing, allowing the creativity of the chemist to move “beyond the box” of traditional cosmetic emulsions.

References

  1. Turbulence and multiphase flow. http://www.lowshearschool.com/?page_id=16919
  2. The effect of shear on oil-water mixture. http://www.lowshearschool.com/?page_id=16933
  3. Zhu Q , Pan Y, Jia X, Li J, Zhang M, Yin L. Review on the stability mechanism and application of water-in-oil emulsions encapsulating various additives. Comprehensive Reviews in Food Science and Food Safety, 18 (6): 1660-1675, 2019

Leor Fay Tal is the Technical Marketing Leader for the Personal Care division of Gattefossé USA. She delivers information on trends and consumers, provides technical marketing support to the company’s sales teams and agents across North America, Canada, and Mexico, and works to promote knowledge and understanding of the company’s ingredients. Prior to Gattefossé, Leor Fay had worked in the R&D Powder Laboratory and then as the Raw Material Regulatory Affairs Specialist at MANA Products. Leor Fay is also an active member of the NYSCC. She organized the April 2018 event Cosmetics in the Middle East, A Regulatory Perspective and now serves as the Secretary for the executive board.

 

 

 

 

Ben Blinder is the Senior Director for Gattefossé USA – Personal Care Division, where he is responsible for the strategic direction and performance of the cosmetic business for Gattefossé in the US and Mexico. Ben holds a chemical engineering degree from Lehigh University and has been working in the personal care industry for 32 years, with extensive experience in strategic and long-range planning, sales and technical management, and new technology search/discovery.  Ben also serves on the NYSCC Scientific Committee.

 

 

 

 

Sunscreen Monograph Proposed New Rules and its Impact on Formulations-Part II

by NYSCC NYSCC No Comments

In my recent blog published in August, changes to the current sunscreen tentative monograph were proposed.  These changes are probably the most drastic changes to the sunscreen monograph since its inception.  In this section, I would like to tackle two key areas related to the changes requested by the FDA.  The first one is the human pharmacokinetics Maximal Usage Trial (MUsT) for sunscreens conducted by the FDA and published in the Journal of the American Medical Association in May 2019.  The second is the response from the Personal Care Product Council (PCPC) to the requests from the FDA for additional safety data.

The FDA conducted a MUsT trial on 4 sunscreen formulations.  The products consisted of 2 sprays, one lotion and one cream. A detailed description of the products used in the study and the sunscreens concentrations used is displayed in Table I below.

Table I

Concentrations of sunscreens in all treatments

Treatment Percent sunscreen contents per label
Avobenzone Oxybenzone Octocrylene Ecamsule
Spray 1 3.00 6.00 2.35 0.00
Spray 2 3.00 5.00 10.00 0.00
Lotion 3.00 4.00 6.00 0.00
Cream 2.00 0.00 10.00 2.00

Twenty-four subjects were enrolled in the study and were randomized into 4 groups.  Each treatment was studied on 6 individuals. All subjects finished the study except one.  Products were applied at a rate of 2 mg/cm2 on 75% of the body area.  Products were applied by a trained expert and were re-applied every 2 hours four times a day.  The study ran for 4 days and panelists were kept indoors.  Thirty blood samples were collected from each panelist over a period of 7 days and were analyzed for their concentration of sunscreens using a validated HPLC method.

Mean maximum plasma concentrations for all sunscreens were calculated for the four treatments and are displayed in Table II.

Table II

Geometric mean maximum plasma concentration for all treatments

Treatment Geometric Mean Maximum plasma concentration, ng/mL (%CV)
Avobenzone Oxybenzone Octocrylene Ecamsule
Spray 1 4.0 (60.9) 209.6 (66.8) 2.9 (102) Not applicable
Spray 2 3.4 (77.3) 194.9 (52.4) 7.8 (113.3) Not applicable
Lotion 4.3 (46.1) 169.3 (44.5) 5.7 (66.3) Not applicable
Cream 1.8 (32.1) Not applicable 5.7 (47.1) 1.5 (166.1)

As seen from the table, all sunscreens tested had higher blood levels than the FDA proposed threshold of 0.5 ng/mL.  These levels were also achieved on the first day of treatment.  The levels obtained triggered the FDA to request safety data not only on the sunscreens studied but also on the 12 sunscreens listed in the monograph.  In addition, the FDA requested MUsT studies to be conducted by the manufacturers on several dosage forms to establish proper guidelines for usage based on safety and efficacy.  Regardless of the results obtained, the FDA insisted on the fact that individuals should not refrain from using sunscreens.

In response to the request from the FDA, the PCPC sent a letter to describe the protocols and studies suggested by the council as well as a timeline.  The PCPC suggested to conduct, in addition to MUsT studies, several surveys on usage of sunscreen products to guide the council in designing the MUsT studies.  The timeline extends till 2023 which should give the industry some breathing room in terms of formulations.  Once the studies are received and completed, an additional timeline delineating the safety of the selected molecules will be proposed.  In the council’s response, two sunscreens were not considered for MUsT studies.  These are Cinoxate and Dioxybenzone.  The fate of these two sunscreens is not determined at this stage yet.

The sunscreen monograph has been evolving for the past 35 years to keep up with the advancement in science.  Formulators, and companies in the field of sun care will have to adjust one more time to the changes.  These changes bring a lot of new challenges and opportunities to innovate and lead.

 

Biography

Dr. Fares started his career in personal care studying the effect of solvents on sunscreen chemicals.  His interest in skin drug delivery especially from polymeric matrices grew during his graduate work at Rutgers, where he completed his Ph. D. in Pharmaceutics.

Dr. Fares worked at Block Drug and GlaxoSmithKline where he held positions in research and development in the areas of skincare and oral care.  After that, he joined L’Oreal where he held several positions of increasing responsibility leading to AVP of skincare.  He is currently the Senior Director of skincare and oral care at Ashland Specialty Ingredients.  Dr. Fares is the author of many publications, and patents and made many presentations in national and international meetings in the areas of suncare, skincare, and oral care.

 

NYSCC Suppliers’ Day Partners with Cosmetic Executive Women (CEW) on New Beauty Award for Supplier’s Innovative Ingredients and Formulation

by james.runkle@drummondst.com james.runkle@drummondst.com No Comments

All Things Beauty to Be Celebrated May 2019 in NYC

 

(New York, NY, December 2018)—The New York Society of Cosmetic Chemists  (NYSCC) has renewed its partnership with CEW by sponsoring a new category in its prestigious Beauty Awards program the “Supplier’s Award: Ingredients and Formulation.”  Mirroring the Academy Awards Science and Technical Achievement awards, the winner of the Supplier’s Award will be announced in advance at the 40th Annual Suppliers’ Day taking place May 7-8, 2019 at the Javits Convention Center in New York City. The winner of the Supplier’s Award will also be recognized at the CEW Beauty Awards luncheon on May 17th at the New York Hilton that attracts more then 3,000 attendees.

Any ingredient and formulation provider that has demonstrated innovation and new technology can submit to the CEW Supplier’s Award.  The deadline for submissions is January 15, 2019.   The submissions can only be entered from a supplier, there is no year limitation, and natural and synthetic ingredients can be entered.  For the submission form and more information click here or email: beautyawards@cew.org

A curated panel of judges from leading beauty and personal care brands including members of the NYSCC Scientific Advisory Committee will select the finalists of the “CEW Supplier’s Award: Ingredients and Formulation.”  Finalists will be announced on April 2, 2019.

“Increasingly, the line between marketing and formulation is being challenged and blurred in product development and this award highlights how all the elements and departments—ingredients, formulation and new technology—need to work together for successful product launches,” said Cathy Piterski, Chair, NYSCC.

The NYSCC Suppliers’ Day is the main trade show and conference for beauty

ingredients, formulations, and delivery innovations.  New educational programming, expanded features and enhanced industry alliances taking place at the event in 2019 include:

-“Fragrance: The Invisible Art,” an all-day, in-depth Fragrance Program, co-produced with the American Society of Perfumers featuring experts in perfume, scent, essential oils, consumer trends, and more.

 

-Spotlight on the important topic of “Safety & Testing.”  Suppliers’ Day will be collaborating with IKW, a leading European Association for German Cosmetic, Toiletry, Perfumery and Detergent, to create a program that addresses important safety and lab testing topics in the industry today.

 

-Suppliers’ Day 2019 has also added a new exhibit hall at the Javits Center, making it the largest event in the show’s history.  This hall will also feature presentation theaters and an innovation hub that will experientially complement specific theater presentations.

 

-Enhanced student engagement with an expanded Future Chemists Workshop that will include college students from Florida, Illinois and other states across the country, as well as a segment for bench chemists who are new to the industry.

 

“I am looking forward to Suppliers’ Day 2019 being the most immersive and experiential event in cosmetics chemistry and product development for our attendees.

Being our 40th Anniversary, we will also look back at the evolution of our industry over the decades and explore current trends that are elevating the importance of formulation and ingredients in beauty innovation,” said Sonia Dawson, Chair-elect, NYSCC.

For more information on NYSCC and Suppliers’ Day visit: https://nyscc.org/suppliers-day or email: suppliersday@nyscc.org.   Companies interested in exhibiting or sponsoring the NYSCC Suppliers’ Day in 2019 should contact Jane McDermott, jmcdermott@nyscc.org or call 212.786.7468.

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About New York Society of Cosmetic Chemists (NYSCC)

Dedicated to the advancement of cosmetic science, the New York Society of Cosmetic Chemists, www.nyscc.org, strives to increase and disseminate scientific information through meetings and publications. By promoting research in cosmetic science and industry, and by setting high ethical, professional and educational standards, we reach our goal of improving the qualifications of cosmetic scientists. Our mission is to further the interests and recognition of cosmetic scientists while maintaining the confidence of the public in the cosmetic and toiletries industry.  Connect with NYSCC on Twitter and Facebook at @NYSCC and Instagram: @NYSCCMAIN

 

About CEW:

CEW is an international organization of 9,000 individual members representing a cross section of beauty and related businesses. The composition of membership includes leading brands, indies, retailers, media and suppliers. CEW’s primary purpose is to provide programs online and in person to develop careers and knowledge of the beauty industry. CEW provides opportunities to connect and gain industry knowledge through networking events, trend reports, industry newsletters, interactive workshops and industry leader talks. For more information, please visit https://www.cew.org/.