What type of finish is commonly used to seal wooden surfaces?

Varnish is commonly used to seal wooden surfaces due to its protective qualities and ability to enhance the natural beauty of the wood. It is a transparent or semi-transparent finish that is typically made from resin dissolved in a solvent, which dries to form a hard, durable coating. The primary function of varnish is to protect against moisture, UV light, and wear, ensuring that the wood remains in good condition over time.

Unlike paint, which covers the surface with color and opacity, varnish maintains the wood's natural grain and texture. Plaster is not suitable for sealing wood surfaces as it is used primarily for wall finishes, and caulking is intended for filling gaps and seams to prevent air and moisture leakage, rather than providing a finish for wooden surfaces. Consequently, varnish is the preferred choice for sealing and finishing wood, making it an ideal option for furniture, cabinetry, and other wooden items.