PHCO1403 Core Concepts in Cosmetic Science, Practical 2 : Colour – A Case Study: Lipstick, University of Northampton

Practical 2: Colour – A Case Study: Lipstick

Introduction

The use of colour cosmetics can go back thousands of years. Some of the first references to the use of decorative cosmetics were around 2000 BC when the royal ladies of Egypt were known to use antimony sulphide to darken their eyes as a beauty statement, white lead to whiten the skin and henna for hair dyes, which as well as to offer protection from evil spirits and improve eye-sight!

Colour cosmetics have been used widely to improve appearance of skin (e.g., hiding skin imperfections), eyes, lips, and nails (e.g., intensifying and/or highlighting). These products are available in different forms: pressed/loose powders, suspensions, emulsions, anhydrous sticks/compacts/pencils, etc., in which adequate pigment dispersion within a vehicle can be delivered uniformly during application. Meanwhile, it must meet the consumers’ expectations, such as appealing look, feel, smell, and maybe taste.

Colorants that are used in the cosmetics are also subject to specific regulations throughout the world, for example, the USA (FDA) and EU (European Commission). This will ensure the products are nontoxic and non-irritating under conditions of use. Approximately 15 organic pigments and 12 inorganic/natural colorants have been widely used due to their good physicochemical stability and tinting strength. Various shades and tinting strength have been created from these chemical compounds. Filler pigments, such as talc and high priced specialties, are also used due to their impact on coverage and skin feel.

Pigments and Dyes

Colorants can be classified as two main categories: dyes and pigments.

Most dyes are organic compounds either synthetic or natural, and they are water or oil soluble. They impart colour by evenly dissolve themselves during the application. They tend to produce more intense and transparent colours compared to pigments, and they can be used in cosmetics such as skin care products or toiletries.

Pigments are insoluble, and they remain in particulate form, imparting their colour through dispersion. Both organic and inorganic pigments are used to create a full range of shades. Pigments offer excellent colour stability, opacity, and coverage. They are commonly used in make-up products, such as eyeshadows, foundations, and lipsticks, allowing for a wide range of shades and hues to be achieved.

A Case Study: Lipstick

Lipsticks are essentially dispersions of colorants in a mixture of oils, fats and waxes and are designed to impart an attractive colour and appearance to the lips.
The typical ingredients used to create lipsticks include: waxes, oils, fats and butters, colour additives, fillers, antioxidants, UV filters, flavour/fragrance, suspending agent for liquid product, preservative.
 
The use of colour additives is strictly controlled by the governor and colourants are approved for specific application areas. Dyes are now not commonly used in the lipsticks because they stain the lip. Pigments including organic/inorganic, lakes, effect/specialty pigments (e.g., providing pearlescent, sparkle, matte and other effects)

The essential processes of lipstick manufacture involve preparing the component blends, such as colour grind and wax/oil blend; dispersion of the pigment blends into carriers such as wax/oil blend to form the mass pouring of mixture into moulds; cooling; packaging. The degree of mixing, heating rates, pouring rates, and cooling rates all contribute to the final appearance and physical stability of the lipstick. ‘flaming’ may also be performed on solid lipsticks, where they move rapidly past a small air flame, partially melting the surface to remove any surface spots and to produce a glossy, smooth, bright appearance.

Practical Objectives

1. To Identify the different type of colour ingredients: e.g. water soluble or oil soluble dyes, and pigments.
2. To gain experience of common colour ingredients used in making colour cosmetic products.
3. To obtain hands on experience using Nix colour sensor.
4. To be able to carry out basic calculations to evaluate colour cosmetic products, e.g. lipsticks.
5. To be able to record the practical they have done, discuss the evaluation data, justify the variations to colour mixture, and provide the general conclusions to be made from these studies.

Colorants Dyes:

1) Water soluble dyes:

• E122 Azorubine (Carmoisine) (Food Red 3 CI 14720)
• FD&C Yellow 5 (Food Yellow 4 CI 19140)
• E133 Brilliant Blue FCF GS (Food Blue 2 CI 42090)

2) Oil soluble dyes:

• Bestoil Yellow YC (Solvent Yellow 33 CI 47000)
• best Green GTSC (Acid Green 25 CI 61570)
•  Bestoil Red BR (Solvent Red 23 CI 26100)

Pigments:

•  E171 Titanium Dioxide (Pigment White 6 CI 77891)
• E172 Duranat Red Iron Oxide (Pigment Red 101 CI 77491)
• E172 Duranat Yellow Iron Oxide (Pigment Yellow 42 & 43 CI 77492)
• E172 Duranat Black Iron Oxide (Pigment Black 11 CI 77499)
• FD&C Yellow 5 Lake (Food Yellow 4:1 CI 19140:1)
• FD&C Blue 1 Lake (Food Blue 2:1 CI 42090:1)
• CI 45410 (D&C Red 28 Lake)
• Red (Insoluble Pigment) Powder (CI 15850)