Solvent

Ingredients with the solvent function help to dissolve other components of the formula and distribute them evenly throughout the product. Due to this, assets, dyes, aromatics and preservatives are better introduced into the composition, and cosmetics themselves receive the necessary transparency, uniformity and comfortable texture. Such substances primarily affect stability, application and sensory properties: the product is more easily distributed over the skin or hair, does not exfoliate and can dry faster or, conversely, retain plasticity longer, depending on the specific formula. The European CosIng database classifies solvent as a standard cosmetic function, and the FDA also indicates that some cosmetic ingredients, such as diethyl phthalate in perfume compositions, can be used as solvents and fixatives. (ec.europa.eu )

For skin and hair, such components usually do not work by themselves, but as a "medium" for the delivery of other substances. They can help distribute moisturizing, cleansing, or caring ingredients so that the product feels more comfortable and acts predictably. A typical example is Propylene Glycol: according to PubChem, in cosmetics it is used not only as a solvent, but also as a moisturizing component, as well as a substance that reduces viscosity. Another common example is Alcohol Denat. or other low molecular weight alcohols in light lotions, sprays, and perfumes: they help to quickly dissolve aromatic and functional substances, making the texture lighter and evaporating quickly. (pubchem.ncbi.nlm.nih.gov)

It is important to understand that safety and comfort depend not so much on the function itself as on the specific substance, its concentration and the entire formulation. The same component can simultaneously perform several roles, such as being a solvent, a carrier, and a texture regulator. Therefore, the presence of such a function in the composition usually does not mean "benefit" or "harm" in itself, but rather a technological task: to help the formula remain effective, stable and pleasant to use. The FDA emphasizes that cosmetic ingredients must be safe when used as intended, and the composition on consumer packaging must be indicated in the list of ingredients. (fda.gov)