CHAPTER 35
Hair Styling: Technology and Formulations

Thomas Krause¹ and Rene C. Rust²

¹ Wella/Procter & Gamble Service GmbH, Darmstadt, Germany

² GSK/Stiefel, Brentford, Middlesex, UK

Basic Concepts

Hair styling aids arrange and maintain hair in a groomed position and impart conditioning, shine, body, and increased manageability.

There are a wide variety of styling aid product forms including hairsprays, gels, mousses, creams, waxes, lotions, and brilliantines. Heated styling implements such as blow‐dryers and curling or straightening irons are also used to achieve style.

Polymers, emollients, and waxes are the main functional ingredients in styling aids. Polymers bond hair strands together to provide hold. Emollients and waxes – amongst other ingredients – increase single hair fiber interaction and smooth cuticles, imparting shine and reduced hair frizz.

Styling aids are in general safe for skin and hair; however, misuse can result in hair damage.

Styling aids may be useful in improving the appearance of hair dermatologic conditions that result in thinning hair, hair dullness, or unruliness.

Introduction

The appearance of a person’s hair, its length, shine, and smoothness, is a strong indicator of general age, health, and attractiveness [1]. In additonal, hairstyle or link to trends may be used to express personality traits or may make a social statement. Marie Antoinette was said to have changed her iconic hairstyle to promote her French identity [2], and who can forget the long flowing hair of the rebellious 1960s flower child? However, today as in the days of Marie Antoinette, hair does not grow naturally into the wide variety of hairstyles desired by men and women – manipulation through brushing, setting, and the use of styling aids is necessary to smooth and arrange the hair into the desired style that is also maintained over time. The use of hair styling products to help achieve hairstyles is also not new – Ancient Egyptians were known to use castor and other oils as hair dressings and beeswax to help style and plait wigs [3].

Styling aids not only correct the hair but can also help transform hair for those with hair loss or hair damage resulting from medical conditions or other factors – hairsprays and other products can give lift to thinning hair, smoothing creams help tame unruly frizz, and gloss serums can help restore a more youthful shine. This chapter describes the wide variety of hairstyling aids – their basic chemistry, utility, and potential issues that clinicians need to be aware of in their everyday practice.

Definitions

Hairstyling is the process of reshaping the hair mass to an arrangement or style that can be maintained over time. Hair, by its nature, is easily reshaped when wet and dried or through the application of heat; however, because of hair’s susceptibility to atmospheric humidity, these changes require the assistance of chemical styling aids to maintain the shape over time. Styling aids with polymers can help improve hair volume and height by increasing hair strand stiffness and hair fiber interactions. Styling aids with emollients and waxes can help smooth out frizz and increase hair shine by aligning fibers and reducing friction and can also have a conditioning effect on the hair fiber (Figure 35.1). Styling products, such as sprays, gels, and waxes, modify only the surface of hair – not the structure itself. These products are not designed to be permanent, unlike permanent waves and chemical straighteners, and the majority of these products are designed for easy removal by shampooing.

Schematic illustration of styling aids can provide improved appearance of hair volume and smoothness. (a) Frizzy unruly hair dried without styling aids. (b) Frizzy unruly hair smoothed with application of styling aids. (c) Fine/thin hair dried without styling aids. (d) Fine/thin hair volumized through the application of styling aids. — **Figure 35.1** Styling aids can provide improved appearance of hair volume and smoothness. (a) Frizzy unruly hair dried without styling aids. (b) Frizzy unruly hair smoothed with application of styling aids. (c) Fine/thin hair dried without styling aids. (d) Fine/thin hair volumized through the application of styling aids.

Physiology

Hair strands are made up of lengths of bundles of keratin polymer chains [4]. These chains are linked by two main types of bonds: strong and weak (Figure 35.2). Strong bonds are made of cystine amino acids and can only be broken chemically (e.g. by permanent wave solutions). Weak bonds include van der Waals, salt bonds, and hydrogen bonds which can be affected by changes in water concentration alone [5, 6].

Schematic illustration of mechanisms to stabilize hair structure and shape via keratin chain interactions. — **Figure 35.2** Mechanisms to stabilize hair structure and shape via keratin chain interactions.

(Source: Umbach, 2004 [7]. Reproduced with permission of John Wiley & Sons.)

Wet setting is the mechanism of shaping hair strands through controlled wetting and drying conditions. Hydrogen bonds can be easily opened by humidity in the air or water accessing the hair from the environment. Rearrangement of the hydrogen bonds will occur by removing water while drying and reformation of new bridges into a different shape by holding the hair strand in the desired shape while drying. Unfortunately, these new bonds are also susceptible to humidity from the environment and may revert back to their natural state of frizzy, curly or weak, straight hair over time.

Styling aids help make the styling process and finished style to be more independent of the molecular interactions inside the hair and more robust against environmental influences because the polymers are less affected by humidity. With the correct polymers, adequate deposition, and sufficient distribution of styling product, significant style holding power can be achieved. Figure 35.3 shows that hair treated with styling aids in a high humidity environment will keep the shape much longer than wet set hair alone.

Schematic illustration of curl retention with and without addition of spray in high humidity. — **Figure 35.3** Curl retention with and without addition of spray in high humidity (85% relative humidity.

(Source: Wella, 2001 [8]. Reproduced with permission of Pocter & Gamble.)

Formulation

Because of very different hair structures, needs, and fashion trends, a very broad range of styling products cover today’s consumer needs and demands (Figure 35.4). Fundamentally, two different types of technology exist; both of these approaches have strong styling benefits and help to protect the hair, but have different styling properties:

Polymer‐based formulations that cover hair with a film and form dry welds between hair strands:
- Advantages: high mechanical strength, dry touch, gloss.
- Disadvantages: will break with mechanical stress, cannot be reformed once broken except by rewetting.
Wax and emollient‐based formulations that deposit hydrophobic material on hair. These hydrophobic materials do not dry over time and create fluid bonds that can be broken and reformed:
- Advantages: no spot welds will break, interaction of single hair fibers can be opened and closed again, styling is remoldable.
- Disadvantages: limited mechanical strength, in high concentrations, can feel waxy/oily, potentially look negative on thin hair.

Polymer formulations

Hairsprays, gels, mousses, and liquid settings work on the principle of film‐forming polymers. The active ingredients can be divided into three groups:

Schematic illustration of the broad range of modern styling aid forms and chemistries. — **Figure 35.4** The broad range of modern styling aid forms and chemistries.

Film‐forming polymers: main ingredient in application such as hairsprays and gels but also as minor ingredients in waxes.
Conditioning and film‐forming polymers: usually in wet applications such as mousses to improve wet combability.
Rheology modifier: usually does not contribute to fixation but controls consistency of the product.

These film‐forming active ingredients are modified to optimized performance by additional ingredients such as emollients (including silicone), solvents, plasticizers, fragrance, and preservatives. Table 35.1 provides a list of typical ingredients found in polymer‐based styling aids.

Table 35.1 Typical ingredients for polymer‐based styling aids.

Ingredient (INCI)	Function	Hairspray	Gel	Mousse
PVP (polyvinylpyrrolidone)	Film former		x	x
Octylacrylamide/acrylates/butylamino‐ethylmethacrylate copolymer	Film former	x
PVP/VA copolymer (PVP/vinylacetate)	Film former	x	x
PQ‐11	Film former			x
PQ‐16	Film former			x
PQ‐4	Film former			x
Chitosan (derived from chitin)	Film former			x
Carbomer (cross‐linked acrylic acid)	Rheology modifier		x
Acrylates/ceteth‐20‐itaconate copolymer	Rheology modifier		x
Hydroxyethylcellulose	Rheology modifier		x
Alcohol	Solvent	x	(x)	(x)
Water	Solvent	(x)	x	x
Dimethicone	Plasticizer	x
Panthenol	Moisturizer	x	x	x
Propane/butane	Propellant	x		x
DME (dimethylether)	Propellant	x		x
Ethylhexymethoxycinnamate	UV‐absorber	x	x	x
PEG‐40‐hydrogenated castor oil	Emulsifier		x	x
Laureth‐4	Emulsifier			x
Aminomethylpropanol	Neutralizer	x	x
Phenoxyethanol	Preservative		x	x
Methylparaben	Preservative		x	x
Fragrance	Scent	x	x	x

Wax and emollient formulations

The area of waxes and emollients covers a broad range of products with a variety of different benefits and applications:

Pure waxes: water‐free formulations, often without preservatives. Mostly compact appearance, provide high hair control. Matte (i.e. low shine) derivatives are also called clay, paste, or putty.
Cream emulsions: contain three main types of ingredients: water, emulsifiers, and oil/wax components. Consistency from soft lotion to rich cream.

Table 35.2 provides a list of typical ingredients found in wax and emollient‐based styling aids.