Comparative Analysis of Hard Gel and Acrylic Systems in Modern Nail Industry: Safety, Durability, and Aesthetic Advantages

The article presents a comparative analysis of two key technological platforms in the nail service industry: classical acrylic (monomer–polymer) systems and modern hard-gel photopolymerizable compositions. The aim of the study is a rigorous scientific substantiation of their differences according to the main criteria: biocompatibility and safety profile, elastic–strength characteristics and coating durability, as well as stability of aesthetic parameters. The methodological component includes a systematic review of the scientific literature at the intersection of polymer chemistry, dermatology, and materials science (using relevant analogies from dental materials science), supplemented by content analysis of industry reports and an examination of practical case studies. The data obtained indicate that hard-gel systems demonstrate a favorable safety profile due to the use of oligomeric matrices of increased molecular weight with reduced sensitizing potential, provided that a full degree of cure is achieved. Their principal advantage is substantially lower volumetric shrinkage during polymerization (less than 5% versus ~21% for acrylates), which reduces shrinkage stresses on the natural nail plate, prevents its damage, and supports physiological growth. Additionally, the use of modern photoinitiators (for example, TPO) in gel formulations provides higher color stability compared with traditional camphorquinone systems. The totality of results confirms that hard-gel technologies are a more advanced solution, ensuring an optimal balance of aesthetics, service life, and preservation of nail plate health. The work is addressed to practicing nail technicians, formulation technologists and developers, educators, and researchers in cosmetology.