Vernis

Vernis is a transparent protective coating applied to surfaces such as wood, metal, and paintings. It forms a hard film that guards against moisture, dirt, and abrasion while enhancing color and depth. In fine-art practice, varnish also unifies the surface gloss and acts as a protective layer that is often removable for conservation.

Composition and types: Vernishes can be natural or synthetic. Traditional varnishes are resin-based mixtures such as dammar, copal, mastic, and shellac dissolved in a solvent; drying oils may be included in oil-based formulations. Modern varnishes use synthetic resins such as alkyds, polyurethanes, and acrylics, and can be oil-, spirit-, or water-based. Finishes range from high-gloss to satin and matte. In art conservation, removable varnishes or formulations that can be selectively removed are used to permit cleaning of the underlying paint.

Applications: In woodworking and furniture, varnish protects wood surfaces from moisture and wear and is used on tables, cabinetry, and floors, often in polyurethane formulations. In musical instruments and decorative objects, varnish enhances grain and color while providing a durable surface. On paintings, a final varnish layer protects the surface, saturates colors, and adjusts reflectivity; such varnishes are typically removed and replaced as the artwork ages.

Application and care: Application is usually by brush or spray in thin coats; multiple coats are applied with light sanding between coats. Drying times depend on formulation and conditions, and full cure may take days to weeks. Solvent-based varnishes are flammable and require good ventilation and proper storage.