Which type of finish should be avoided in high-moisture environments?

In high-moisture environments, shellac should be avoided as a finish because it is not water-resistant. Shellac is a natural resin that dissolves in alcohol, making it vulnerable to damage from water and humidity. When exposed to moisture, shellac can break down and lose its protective qualities, leading to potential degradation of the wood surface beneath.

In contrast, other finishes like polyurethane varnish and oil-based paint are designed to provide better moisture resistance. Polyurethane varnish creates a tough, protective layer that is capable of withstanding exposure to water, making it suitable for areas with high humidity. Oil-based paints also offer a degree of moisture resistance, although they may not be as robust as polyurethane for such applications.

Water-based finishes can provide some level of moisture protection, but their performance may vary greatly depending on the specific product. Therefore, shellac is less suitable for high-moisture environments compared to these other finishing options.