Purpose
Hair gel is a styling product that comes in traditional gel consistency, liquid consistency or a spray. It usually comes in several holding strengths, from light to strong, and provides a wetter look than mousse or hairspray. When styling with gel, it's best to apply the gel to wet hair and either let your hair air dry or blow it dry with a hairdryer. Gel is not designed for use on dry hair.
Main Ingredient
In order to shape hair, the hair cuticle's consistency must be strengthened. The main ingredient in hair gel does this. In most gels, it is a plastic called PVP, which is a polymer sealer. The polymers in PVP are dissolved in water or alcohol and form a clear film between each hair strand, attaching the hair strands to one another. The experts from The Chemical Company call this "capillary power," because it's similar to how blood capillaries work.
When gel is applied to wet hair, the PVP or similar ingredient absorbs water quickly. When the gel dries completely, it forms a fixed connection between hair strands.
Removing
Since the main ingredient in hair gel is water-soluble, if you want to refresh your style, reactivate the gel by spraying a little water into your hair and reshaping.
To remove the gel, shampoo or rinse with water to break the PVP's water-soluble connections.
Drawbacks
Gel is a less popular hairstyling product than mousse or cream because it has several drawbacks.
Gels are sticky to use until they are dry. Since they are water soluble, if it is rainy or especially humid, the gel might get sticky again or deactivate altogether. Some gels contain alcohols, which can stain certain fabrics and dry out hair. If you already have dry hair, gels with alcohol are bad choices for you. Gels build on hair follicles over time, especially with everyday use. If you plan to use gel as your primary hairstyling product, you'll want to use a clarifying shampoo at least once a week.
There are low-quality and high-quality gels. According to All Hairstyles Haircuts, if you apply a low-quality gel to coarse hair, the hair will get sticky and coarser than it was in the first place.