barnices

Barnices, or varnishes, are transparent finishes applied to wood, metal, and artworks to protect the surface and enhance appearance. They form a hard, clear film that adds gloss or depth without masking the underlying grain. Varnishes differ from paints and lacquers in that they do not incorporate pigment; some formulations may yellow slightly with age.

Most varnishes consist of a resin dissolved in a solvent or water, combined with a binder such as a drying oil in traditional formulations. Natural resins include damar, copal, and shellac; modern varnishes use synthetic resins such as alkyds, acrylics, or polyurethane. Drying occurs by solvent evaporation and chemical cross-linking, sometimes aided by driers or UV stabilizers.

Common types include oil-based varnishes, alkyd varnishes, polyurethane varnishes, acrylic varnishes, and shellac. In art conservation, removable varnishes are designed to be dissolved with solvents and replaced. For furniture and floors, polyurethane and acrylic varnishes offer high abrasion resistance; oil-based varnishes can deepen color but may amber over time. Finish can be glossy, satin, or matte.

Application methods include brushing, wiping, or spraying. Cure time depends on temperature, humidity, substrate, and film thickness. Recoating requires fully cured surfaces and compatibility of layers. Maintenance involves cleaning and occasional reapplication to restore protection if the film becomes dull or scratched. Safety concerns include volatile organic compounds (VOCs); proper ventilation and protective equipment are advised during use and disposal.

Storage should be in tightly closed containers, away from heat sources and direct sunlight. Shelf life varies by product but unopened varnishes can be long-lasting; once opened, seal promptly to prevent skinning and drying.