What property is essential for nail enamel to provide a glossy finish?

The essential property for nail enamel to provide a glossy finish is plasticiser. Plasticisers are compounds that enhance the flexibility and workability of materials. When added to nail enamel, they create a smooth and shiny appearance by reducing brittleness and preventing the polish from chipping or cracking. This helps the polish maintain an appealing gloss and contributes to its overall durability.

In contrast, preservatives are primarily used to inhibit microbial growth and extend the shelf life of the product, but they do not contribute directly to the glossy finish. Pigments are responsible for the color of the enamel but do not affect the shininess or luster. Waxes can provide some sheen and thickness to formulations but are not as critical in achieving the high gloss that plasticisers offer. Thus, plasticiser is the key ingredient that directly influences the glossy finish of nail enamel.