Hair gel is a hairstyling product

Hairstyling product

Hairstyling products are used to change the texture or shape of the hair, or to hold it in place in a certain style. Applied properly, most styling products will not damage the hair apart from drying it out; most styling products contain alcohols, which can dissolve oils...

 that is used to stiffen hair

Hair

Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....

 into a particular hairstyle

Hairstyle

A hairstyle, hairdo, or haircut refers to the styling of hair, usually on the human head. The fashioning of hair can be considered an aspect of personal grooming, fashion, and cosmetics, although practical, cultural, and popular considerations also influence some hairstyles.-History of...

. The results it produces are usually similar to, but stronger than, those of hair spray

Hair spray

Hair spray is a common cosmetic product that is sprayed onto hair to keep it stiff or in a certain style...

 and hair wax

Hair wax

Hair wax is a thick hairstyling product containing wax, used to assist with holding the hair. In contrast with hair gel, most of which contain alcohol, hair wax remains pliable and has less chance of drying out...

, and weaker than those of hair glue.

Types

Many brands of hair gel

Gel

A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state...

 in North America and the United Kingdom come in numbered variants. Higher numbered gels maintain a greater "hold" on hair, while lower numbers do not make the hair as stiff and in some products give the hair a wet look. A category typically referred to as "ethnic" gels are designed and manufactured specifically for sculpting the hair texture common to African Americans. Ampro Industries

Ampro

Ampro Industries, Inc. is an American ethnic hair care and cosmetics company based in Memphis, Tennessee. Ampro was founded in 1947. Its product lines include a wide range of styling and treatment products, specially formulated for ethnic consumers, including gels, shampoos, conditioners and...

 is a common example of this category.

Some forms of hair gel include temporary hair coloring for the hair, including variants in unnatural colors associated with various subculture

Subculture

In sociology, anthropology and cultural studies, a subculture is a group of people with a culture which differentiates them from the larger culture to which they belong.- Definition :...

s, and are popular within the goth

Gothic fashion

Gothic fashion is a clothing style worn by members of the Goth subculture; a dark, sometimes morbid, eroticized fashion and style of dress. Typical Gothic fashion includes dyed black hair, black lips and black clothes. Both male and female goths wear dark eyeliner and dark fingernails. Styles are...

 and raver

Raver

Raver or ravers may refer to:* Raver, Maharashtra, a city in India* Raver, a party-goer: in the 1960s and 1970s, a "party animal"; since the 1980s, more specifically an aficionado of raves...

 subcultures.

Cationic polymers

Cationic polymer

Polymer

A polymer is a large molecule composed of repeating structural units. These subunits are typically connected by covalent chemical bonds...

s are one of the main functional component of hair gel. The positive charges in polymer causes it to stretch, making the gel more viscous

Viscosity

Viscosity is a measure of the resistance of a fluid which is being deformed by either shear or tensile stress. In everyday terms , viscosity is "thickness" or "internal friction". Thus, water is "thin", having a lower viscosity, while honey is "thick", having a higher viscosity...

.
Hair gels resist natural protein conformations and allow hair to be styled and textured. This is because the stretched-out polymer takes up more space than a coiled polymer and thus resists the flow of solvent molecules around it. The positive charges also bind the gel to the negatively charged amino acid

Amino acid

Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...

s on the surface of the keratin

Keratin

Keratin refers to a family of fibrous structural proteins. Keratin is the key of structural material making up the outer layer of human skin. It is also the key structural component of hair and nails...

 molecules in the hair. More complicated polymer formulas exist, e.g. a copolymer of vinylpyrrolidone, methacrylamide, and N-vinylimidazole.